2024-02-22 Architectural Design Board PacketOF BbMG
ti Agenda
Edmonds Architectural Design Board
1,00
REGULAR MEETING
BRACKETT ROOM
121 5TH AVE N, CITY HALL- 3RD FLOOR, EDMONDS, WA 98020
FEBRUARY 22, 2024, 6:00 PM
REGULAR MEETING INFORMATION
This is a Hybrid meeting. Attendees may appear in person or on-line via the zoom link provided.
Physical Meeting Location: Brackett Room, 3rd Floor Edmonds City Hall 121 5th Avenue N.
Zoom Link: https://edmondswa-
gov.zoom.us/j/88959586932?pwd=RzdPWUIwM09PZ1k1MHN2eWM1YXphZz09 Passcode:591531
1. CALL TO ORDER
Roll Call
2. APPROVAL OF AGENDA
3. AUDIENCE COMMENTS
Statement: This is an opportunity to comment regarding any matter not listed on the agenda as
public hearing. Speakers are limited to five minutes. Please clearly state your name and city of
residence.
4. APPROVAL OF MINUTES
1. Approval of Minutes January 25th meeting
S. NEW BUSINESS
2. 2024 ADB Work Plan
3. Review of the Urban Design Element from the 2020 Comprehensive Plan
6. PUBLIC HEARINGS
7. BOARD REVIEW ITEMS
Items requiring review and recommendation from the ADB.
8. BOARD DISCUSSION ITEMS
9. ADB MEMBER COMMENTS
10. ADJOURNMENT
Edmonds Architectural Design Board Agenda
February 22, 2024
Page 1
Architectural Design Board Agenda Item
Meeting Date: 02/22/2024
Approval of Minutes January 25th meeting
Staff Lead: Mike Clugston
Department: Architectural Design Board
Prepared By: Michelle Martin
Background/History
N/A
Staff Recommendation
Review and approve minutes from January 25th meeting.
Narrative
Draft minutes from January 25th meeting attached.
Attachments:
ADB 01252024_draft
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CITY OF EDMONDS
ARCHITECTURAL DESIGN BOARD
Minutes of Regular Meeting
January 25, 2024
Chair Bayer called the hybrid meeting of the Architectural Design Board to order at 6:02 p.m. in the Brackett
Room at Edmonds City Hall, 121— 5th Avenue North, Edmonds, Washington.
Board Members Present
Kim Bayer, Chair
Alexa Brooks, Vice Chair
Alex Hutchinson
Maurine Jeude
Corbitt Loch
Steve Schmitz
Board Members Absent
None
Staff Present
Mike Clugston, Acting Planning Manager
Jeff Levy, Senior Planner
New Board Member Hutchinson was welcomed. All board members and staff introduced themselves.
APPROVAL OF AGENDA
The agenda was approved as presented.
AUDIENCE COMMENTS
None
APPROVAL OF MINUTES
December 11, 2023 ADB Special Meeting Minutes
MOTION MADE BY BOARD MEMBER JEUDE, SECONDED BY BOARD MEMBER SCHMITZ,
TO APPROVE THE MINUTES AS PRESENTED. MOTION PASSED UNANIMOUSLY.
NEW BUSINESS
A. Election of Officers
Board Member Jeude nominated Chair Bayer to serve another term as Chair.
Architectural Design Board Meeting
Minutes of Regular Meeting
January25, 2024
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Chair Bayer was unanimously re-elected Chair.
Board Member Jeude nominated Vice Chair Brooks to serve another term as Vice Chair. Vice Chair Brooks
nominated Board Member Schmitz to serve as Vice Chair.
Alexa Brooks was re-elected Vice Chair.
PUBLIC HEARINGS
None
BOARD REVIEW ITEMS
Acting Planning Manager Clugston discussed items that will be coming to the Board in the near future. The
main focuses this year will be the Comprehensive Plan update and Design Review codes and processes.
BOARD DISCUSSION ITEMS
• Vice Chair Brooks wondered if the Board could still meet on months when there is no actual business
in order to get updates on previous topics. Chair Bayer acknowledged that a lot of meetings were
cancelled when there were no projects to review, but she thought there were still things they could be
discussing. Mr. Clugston stated that he thought this year would be very full of Comprehensive Plan and
Design Review code and process discussions. It is likely they will need all the meetings just to address
those. There was discussion about forming subcommittees to address priority topics such as multifamily
design standards. Mr. Clugston explained that staff intended to put together a list of topics in a work
plan for them to take a look at in February. Chair Bayer expressed interest in prioritizing the list,
potentially beginning to assign subcommittees, and also starting to think about when they might be able
to have a joint meeting with the Planning Board. Board Member Loch was not in favor of having
meetings when there is no work. He suggested that the Board receive design standards from staff when
they are ready to review and mark up with their individual comments. He encouraged staff to take
advantage of the ADB members' unique areas of expertise. Board Member Schmitz agreed. There was
general discussion about the uncertainty of the process and the timeline at this point.
• Mr. Levy indicated he would send out information about HB 1110, the middle housing bill, and HB
1337, regarding accessory dwelling units.
• Board Member Schmitz requested that staff include the ADB early in the Comp Plan drafting process,
even before they have made decisions about the code, so the ADB can begin to get up to speed on what
the possibilities might be and form opinions.
• Chair Bayer referred to the elimination of the two-phase public hearing for design review and wanted
to know how they will be able to make sure they get public input and are able to do all they need to do
with just one design review meeting. Commissioner Schmitz thought it would actually help them get to
the point and clarify what they really want to see with the design standards.
• Chair Bayer wondered about having a different regular meeting date since the 4th Thursdays are
cancelled in November and December. Mr. Clugston said he could look to see when the room is
available but noted they could always schedule a special meeting when there is a conflict.
• Mr. Levy assured the Board that while it might seem a little slow, things are going to get very busy this
year.
Architectural Design Board Meeting
Minutes of Regular Meeting
January 25, 2024
Page 2 of 3
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ARCHITECTURAL DESIGN BOARD MEMBER COMMENTS
No additional comments
ADJOURNMENT
The meeting was adjourned at 6:54 p.m.
Architectural Design Board Meeting
Minutes of Regular Meeting
January 25, 2024
Page 3 of 3
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Architectural Design Board Agenda Item
Meeting Date: 02/22/2024
2024 ADB Work Plan
Staff Lead: Jeff Levy
Department: Planning Division
Prepared By: Michael Clugston
Background/History
This is a new item.
Staff Recommendation
Review proposed work plan.
Narrative
The ADB's code and policy touches in the work plan are estimates but generally driven by the City's
periodic comprehensive plan update process due at the end of 2024, the Planning Board's 2024 work
plan for multifamily design standards, and the requirements from House Bill 1293 regarding design
standards and processes, changes to which must be adopted by Council by mid-2025. There will still be
occasional project reviews as well but those will only be scheduled when they are ready for the Board's
review.
Attachments:
Attachment 1 - 2024 ADB work plan
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Architectural Design Board
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January February March April May June
July August September October November December
Week of
Ilan ".. IS -Jan 22-Jan 29-Jan
S-Feb 12-Feb 19-Feb 126F.b
l4M.r III.M.r 1&Mar 25-Mar
1-Apr 8-Apr llSApr 22-Apr "-Apr
6-May 13-May 20-May 21-May
3-Jun 10.),m 17-Jun 29-Jun
1-Ju1 8-Jul 15-Jul 22-Jul 29-Jul
5-Aug 12-Aug 19-Aug 26-Aug
2-Sep 9-Sep I6-Sep 23-Sep 30-Sep
1-0R 19-Oct 21-0R IM0.
4Nov 11-Nov IB-Nov 25-Nov
2-Dec 9-Dec I6-0ec 2}De, 3 Erec
Architectural Design Board
25-Jan
2D-Jun
18-Jul
19-Sep
Comp Plan Urban Design Review
Begin Review and Comment
First Draft Review - Individual Discussed
First Draft Review - Consolidated Submitted
Final ADB Recommendation Submitted
Multi -Family Design Standards
Begin Review and Comment
TBD
TBD
TBD
TBD
Final MF Design Standards Recommendation
SB 1293 - Clear and Objecdve Design Standards
Begin Review and Comment
TBD
TBD
TBD
TBD
Final SB 1293 Reommendatmn Submitted
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Architectural Design Board Agenda Item
Meeting Date: 02/22/2024
Review of the Urban Design Element from the 2020 Comprehensive Plan
Staff Lead: Jeff Levy
Department: Planning Division
Prepared By: Michael Clugston
Background/History
Edmonds is currently doing a periodic update of its comprehensive plan consistent with the
requirements of the Growth Management Act (GMA) in RCW 36.70A.130. As part of that work, and
consistent with the ADB's powers and duties in ECC 10.05.040, the Board will be reviewing the adopted
Urban Design portion of the Community Culture and Urban Design Element of the existing
comprehensive plan. This is not a required element of the comprehensive plan, but rather is optional as
noted in RCW 36.70A.080.
Staff Recommendation
The Board will begin review of and comment on the existing design guidance in the 2020 Comprehensive
Plan, which is included as Attachment 1.
Narrative
The goal of this work is for the Board to determine whether particular existing language should remain
as -is, needs to be updated, needs to be removed, or whether some new information needs to be added.
For context, the final bill report for HB 1293 is included (Attachment 2), which offers a good summary to
keep in mind while looking at the Urban Design section. It is not directly enforceable in this optional
element but would be a good filter as we think of "clear and concise" language throughout the entire
Comp Plan and in future standards and regulations. Additionally, on January 25, the Board requested
the latest guidance documents from the Department of Commerce for HB 1337 (ADUs - Attachment 3)
and HB 1110 (middle housing - Attachment 4). These provide clear direction for what is mandated by
the state.
The existing design guidance in the 2020 comprehensive plan is found on pages 122 - 129 and is divided
into four subheadings:
1) Urban Design Goals and Policies
2) General Design Objectives (for site design, building form, and building facade)
3) Urban Design Goals & Policies for Specific Areas (Downtown/Waterfront Activity Center, Highway
99 Corridor, and Neighborhood Commercial Areas)
4) Streetscape and Street Trees Goals and Policies
Both of the Implementation Actions related to the Streetscape and Street Trees Goals and Policies were
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not met by 2018. An Urban Forest Management Plan was developed and adopted in 2019 and the
Street Tree Plan is currently under review.
Next Steps
As noted in the 2024 Work Plan, three additional Board touches of the comprehensive plan are
anticipated over the next several months:
1) In March, a first draft review of individual comments will be discussed
2) In April, a first draft review of consolidated comments will be discussed
3) In May, final ADB recommendation is needed
Attachments:
Attachment 1
- Urban Design Language from 2020 Comp Plan
Attachment 2
- HB 1293 summary (clear and objective standards)
Attachment 3
- Commerce ADU Guidance (HB 1337)
Attachment 4
- Middle Housing Model Ordinances (HB 1110)
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Urban Design
General. The man-made environment is an expression of human culture and reflects, in physical
form, the social values of the members of the community. The manner in which the man-made
elements are integrated into the natural environment helps create the community's special
characteristics and contribute to the quality of life in Edmonds.
The beauty and variety of the natural surroundings in Edmonds and the historical development of the
City have combined to create an interesting and visually attractive community. Views, especially
views from public corridors and public places, are an important community asset.
However, unsightly development — of poor quality or design — does exist in the City. Aging buildings
in some parts of the City can create an aesthetic problem if they are not maintained. Retaining
historic buildings can positively reinforce the character of an area such as downtown. The strip type
of development along Highway 99 has often resulted in economic underdevelopment of private
properties that end up being aesthetically displeasing.
Although utility wires are placed underground where new development takes place, overhead wires
still exist in most of the older parts of the City where they interfere with views and create visual
blight.
Commercial signs contribute to the color and variety of community life as well as providing an
important function but they may also create discordant and unsightly conditions where they are
excessive or of poor design.
Street landscaping has been utilized in the past on a limited basis. However, in many areas, parking
lots, access roads, streets and buildings can be better integrated with the landscape.
Urban Design Goals & Policies
The general design objectives provided with this goal are intended to provide general guidance, while
the subsequent design objectives (Goals B, C and D) for specific locations or situations are intended
to supplement the general objectives and add more guidance for those specific situations.
Each key goal in this element (or section) is identified by an alphabet letter (for example, "D").
Goals are typically followed by associated policies and these are identified by the letter of the goal
and a sequential number (for example, "D.2")
General Design Goal A. Design goals and objectives are intended to provide a set of tools for the
City to use to guide future development to result in high quality, well -designed, and sensitive
projects that reflect the values of the citizens of Edmonds. The goals and related objectives
contained in this section are intended to:
• improve the physical appearance and character of Edmonds,
• improve retail and pedestrian circulation options,
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• improve business opportunities,
• protect natural environments using sustainable design practices,
• protect and enhance the residential character of Edmonds.
General Design Objectives
Design Objectives for Site Design. The development of parking lots, pedestrian walkways and
landscaping features is an integral part of how a building interacts with its site and its surrounding
environment. Good design and site planning improves access by pedestrians, bicycles and
automobiles, minimizes potential negative impacts to adjacent development, reinforces the
character and activities within a district and builds a more cohesive and coherent physical
environment.
A.1 Vehicular Access. Reduce the numbers and width of driveways (curb cuts) in order
to improve pedestrian, bicycle and auto safety.
A.2 Layout of Parking. Locating buildings in proximity to the street to facilitate direct
pedestrian access and help define the street edge. Parking should be placed to the
side and rear.
A.3 Connections On- and Offsite. Design site access and circulation within and
between sites to encourage linkages for pedestrians, vehicles, and bicycles. Special
attention should be paid to providing and improving connections to transit.
A.4 Building Entry Location. Building entries should be configured to provide clear
entry points to buildings, be oriented to pedestrian walkways/pathways, and
support the overall intent of the streetscape environment. Space at the entry for
gathering or seating is desirable for residential or mixed use buildings.
A.5 Setbacks. Create and maintain the landscape and site characteristics of each
neighborhood area and provide a common street frontage tieing each site to its
neighbor. Setbacks should be appropriate to the desired streetscape, providing for
transition areas between public streets and private building entries where a variety
of activities and amenities can occur.
A.6 Open Space. For residential settings, create green spaces to enhance the visual
attributes of the development and provide places for interaction, play, seating, and
other activities.
A.7 Building/Site Identity. Improve pedestrian access and way -finding by providing
variety in building forms, colors, materials and individuality of buildings.
A.8 Weather Protection. Provide covered walkways and entries for pedestrian weather
protection.
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A.9 Lighting. Provide adequate and appropriate illumination in all areas used by
automobiles, bicycles and pedestrians — including building entries, walkways,
parking areas, circulation areas and other open spaces — to support activity and
security.
A.10 Signage. Encourage signage that provides clear information and direction for
properties and businesses while preventing the strectscape from becoming
cluttered. Encourage the use of graphics and symbols in signage to support the
city's emphasis on uniqueness and the arts.
A.I I Site Utilities, Storage, Trash and Mechanical Systems. Minimize the noise, odor
and visual impacts of utility systems using such features as landscaping, building
forms, or integrated design.
A.12 Integrating Site Features. Integrate natural landscape features and unique landforms
— such as rocky outcroppings or significant trees — into site design whenever
possible.
A.13 Landscape Buffers. Use landscaping and/or other features such as fences to
maintain privacy and create a visual barrier between incompatible uses. These
buffering techniques should also be used to soften hard edges (such as the
perimeters of parking lots) and reinforce pedestrian ways and circulation routes.
Native plants and rain gardens should be promoted as alternatives to lawns and
runoff retention areas.
Design Objectives for Building Form. Building height and modulation guidelines are essential
to create diversity in building forms, minimize shadows cast by taller buildings upon the
pedestrian areas and to ensure compliance with policies in the city's Comprehensive Plan.
Protecting views from public parks and building entries as well as street views to the mountains
and Puget Sound are an important part of Edmonds character and urban form.
A.14 Building Form. Encourage new construction to avoid repetitive, monotonous
building forms.
A.15 Massing. Reduce the apparent bulk and mass of buildings by encouraging human
scale elements in building design and/or by subdividing building masses vertically
or horizontally.
A.16 Roof Modulation. Use roof forms to help identify different programs or functional
areas within the building and support differentiation of building form and massing.
Roof design, in combination with wall modulation, can allow for additional light to
enter buildings or pedestrian spaces.
A.17 Wall Modulation. Variation in materials, decorative elements, or other features
should be employed to support pedestrian scale environments and streetscapes, or
to help break up large building masses to keep in scale with the surrounding
environment.
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Design Objectives for Building Facade. Building facade objectives ensure that the exterior of a
building — the portion of a building that defines the character and visual appearance of a place — is
of high quality and demonstrates the strong sense of place and integrity valued by the residents of
the City of Edmonds.
A.18 Building Facade Design. Encourage building fagades that reinforce the appearance
and consistency of streetscape patterns while supporting diversity and identity in
building design.
A.19 Window Variety and Articulation. Use window size and placement to help define
the scale and character of the building. Use the organization and combinations of
window types to reinforce the streetscape character or to provide variation in a
facade, as well as provide light and air to the building interior.
A.20 Variation in Facade Materials. Employ variation in materials, colors or design
elements on building fagades to help define the scale and style of the structure.
Variation in facade materials can help reduce the apparent bulk of larger buildings
while allowing variety and individuality of building design.
Urban Design Goals & Policies for Specific Areas
In addition to the general design goal and objectives described above under Goal A, supplemental
design objectives are outlined below for specific areas or districts within the city.
Each key goal in this element (or section) is identified by an alphabet letter (for example, "D").
Goals are typically followed by associated policies and these are identified by the letter of the goal
and a sequential number (for example, "D.2")
Urban Design Goal B: Downtown/Waterfront Activity Center. Design objectives and
standards should be carefully crafted for the Downtown/Waterfront Activity Center to encourage
its unique design character and important place -making status within the city.
B.1 Vehicular Access and Parking. Driveways and curb cuts should be minimized to
assure a consistent and safe streetscape for pedestrians. When alleys are present,
these should be the preferred method of providing vehicular access to a property
and should be used unless there is no reasonable alternative available.
Configuration of parking should support a "park and walk" policy that provides
adequate parking while minimizing impacts on the pedestrian streetscape.
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B.2 Pedestrian Access and Connections. Improve pedestrian
access from the street by locating buildings close to the
street and sidewalks, and defining the street edge. Cross
walks at key intersections should be accentuated by the
use of special materials, signage or paving treatments.
Transit access and waiting areas should be provided where
appropriate.
B.3 Building Entry Location. Commercial building entries
should be easily recognizable and oriented to the
pedestrian streetscape by being located at sidewalk grade.
O
Building Setbacks. Create a common street frontage view
with enough repetition to tie each site to its
neighbor. Encourage the creation of public
spaces to enhance the visual attributes of
the development and encourage outdoor
interaction. In the Waterfront area west of
the railroad, buildings should be set back
from the waterfront to preserve and provide
a buffer from existing beach areas. In the
Waterfront area, site layout should be
coordinated with existing buildings and
proposed improvements to provide views of
the water, open spaces, and easy pedestrian access to the beach.
Building/Site Identity. In the downtown area, retain a connection with the scale and
character of downtown through the use of similar materials, proportions, forms,
masses or building elements. Encourage
new construction to use designs that
reference, but do not replicate historic
forms or patterns.
Weather Protection. Provide a covered
walkway for pedestrians traveling along KWIC
public sidewalks or walkways.
B.7 Signage. Lighting of signs should be indirect or
minimally backlit to display lettering and symbols or
graphic design instead of broadly lighting the face of the
sign. Signage using graphics or symbols or that
contributes to the historic character of a building should
be encouraged.
::
Art and Public Spaces. Public art and amenities such as '
mini parks, flower baskets, street furniture, etc., should
be provided as a normal part of the public streetscape.
Whenever possible, these elements should be continued
in the portion of the private streetscape that adjoins the public streetscape. In the 4tn
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Avenue Arts Corridor, art should be a common element of building design, with
greater design flexibility provided when art is made a central feature of the design.
B.9 Building Height. Create and preserve a human scale for downtown buildings.
Building frontages along downtown streetscapes should be pedestrian in scale.
B.10 Massing. Large building masses should be subdivided or softened using design
elements that emphasize the human scale of the streetscape. Building facades
should respect and echo historic patterns along downtown pedestrian streets.
B.11
Building Fagade. Provide a human scale streetscape, breaking up long facades into
defined forms that continue a pattern of individual and distinct tenant spaces in
commercial and mixed use areas. Avoid blank, monotonous and imposing building
facades using design elements that add detail and emphasize the different levels of
the building (e.g. the top or cornice vs. the pedestrian level or
building base).
B.12 Window Variety and Articulation. In the downtown retail and
mixed commercial districts, building storefronts should be
dominated by clear, transparent glass windows that allow and
encourage pedestrians to walk past and look into the
commercial space. Decorative trim and surrounds should be
encouraged to add interest and variety. Upper floors of
buildings should use windows as part of the overall design to
encourage rhythm and accents in the fagade.
Urban Design Goal C: Highway 99 Corridor. Additional Design Objectives for the Highway
99 Corridor should support its function as a locus of commercial and potential mixed use activity,
building on the availability of multiple forms of transportation and its proximate location to
surrounding neighborhoods.
C.1 General Appearance and Identity. Design of buildings and spaces along Highway
99 should encourage a feeling of identity associated with different sections of the
highway.
C.2 Site Design. Site design should allow for vechicular access and parking as well as
safe access and circulation for pedestrians. Whenever possible, sites should provide
connections between adjacent businesses and between businesses and nearby
residential neighborhoods.
C.3 Landscaping and Buffering. Landscaping, fencing or other appropriate techniques
should be used to soften the street front of sites and also used to buffer more
intensive uses from adjoining less intensive use areas (e.g. buffer commercial from
residential development).
Urban Design Goal D: Neighborhood Commercial Areas. Design in neighborhood
commercial areas should seek to support the function of the neighborhood center while paying
close attention to its place within the neighborhood setting.
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D.1 Landscape and Buffering. Special attention should be paid to transitions from
commercial development to surrounding residential areas, using landscaping and/or
gradations in building scale to provide compatible development.
Streetscape and Street Trees
General. Trees are a valuable asset to the community.They help absorb stormwater, provide habitat
for wildlife, clean pollution from the air, and give both summer shade and aesthetic pleasure. Trees on
public property and within the right-of-way are a common feature of urban design.
"Streetscape" is a term that refers to the street environment, often including pedestrian features,
landscaping, lighting, pavement materials, and signage. The streetscape plays an important role in the
livability and character of Edmonds. Public streets, with their associated walkways and pedestrian
spaces, provide the places for people to interact with their neighbors, accommodate public events and
commerce, promote human needs for enjoyment and exercise including arts and aesthetics, and can
improve the ecological function of the city. When designed properly, the Streetscape complements the
urban design elements incorporated into the development of private property.
A Streetscape Plan was developed in 2002 by the Parks, Recreation, and Cultural Services
Department and updated in 2006. It focused on the public realm along streets, certain areas of the City
such as the 4th Avenue Arts Corridor, Highway 99 International area, and downtown. The Streetscape
Plan included a Street Tree Plan as an appendix. The Street Tree Plan has since been updated to
reflect lessons learned about preferred tree species in certain locations. The Street Tree Plan provides
guidance to the City in selecting and maintaining street trees in specific areas.
In 2011, the City adopted a `Complete Streets' program that prioritizes accommodating the needs of
all users — including pedestrians, bicyclists, transit and individual vehicles — in transportation projects.
The intent is to create safe environments for people of all ages and abilities while improving
transportation options and connections between the City's destinations and centers of activity. A
complete streets approach can improve the ability of residents and visitors to experience the City in a
variety of ways while improving environmental quality, enhancing economic activity, and promoting
healthy lifestyle.
Where feasible, street trees or other landscaping located between the travel lane and the sidewalk can
improve the pedestrian experience.
This section has a key goal and several policies specifically related to Streetscape and street trees
within the public right of way.
Streetscape and Street Trees Goals & Policies
Each key goal in this element (or section) is identified by an alphabet letter (for example, "D").
Goals are typically followed by associated policies and these are identified by the letter of the goal
and a sequential number (for example, "D.2")
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Streetscape and Street Trees Goal A. Enhance the public realm through streetscape and street
tree choices.
A.1. Encourage improvements to streets that link parks, open spaces, recreation
centers, employment centers, and transportation nodes.
A.2. Balance the need for short-term parking for shoppers and loading for businesses
with the need for pedestrian -oriented design, especially downtown.
A.3. As opportunities arise, provide for sustainable streetscapes that can enhance the
natural environment, help ensure safety, and complement the characteristics of
the neighborhood or district in which they are located.
A.4. Promote the planting and maintenence of landscaping and street trees to enhance
City gateways and connections; strengthen the character and identify of
downtown and other retail/commercial centers; and improve the pedestrian
environment.
A.5. Seek to maintain and retain existing healthy trees in the rights -of -way without
sacrificing public safety or public infrastructure or allowing a hazard or nuisance
A.6. Selecting and managing trees for planting in the public rights -of -way should be
based on a variety of factors, such as aesthetics, view corridors, safety,
maintenence, size, spacing, longevity, location, utilities, and adaptability to the
regional environment.
Implementation Actions
Implementation actions are steps that are intended to be taken within a specified timeframe to address
high priority Streetscape and Street Tree goals. The actions identified here are specifically called out
as being important, but are not intended to be the only actions or measures that may be used by the
City.
Action 1: Develop an update to the Street Tree Plan by the end of 2018.
Action 2: Develop an Urban Forest Management Plan by the end of 2018.
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FINAL BILL REPORT
ESHB 1293
C 333 L 23
Synopsis as Enacted
Brief Description: Streamlining development regulations.
Sponsors: House Committee on Housing (originally sponsored by Representatives Klicker,
Leavitt, Barkis, Jacobsen, Waters, Chapman, Reed and Graham).
House Committee on Housing
Senate Committee on Local Government, Land Use & Tribal Affairs
Background:
Growth Management Act.
The Growth Management Act (GMA) is the comprehensive land use planning framework
for counties and cities in Washington. The GMA establishes a wide array of planning
duties for 28 counties, and the cities within those counties, that are obligated to satisfy all
planning requirements of the GMA. These jurisdictions are sometimes referred to as fully
planning under the GMA.
Counties that fully plan under the GMA must designate urban growth areas (UGA), within
which urban growth must be encouraged and outside of which growth may occur only if it
is not urban in nature. Each city in a county must be included in a UGA. Fully planning
jurisdictions must include within their UGAs sufficient areas and densities to accommodate
projected urban growth for the succeeding 20-year period.
Project Review.
Before developing land, a developer must obtain permits from the local government that
allow the development. These permits can include land use permits, environmental permits,
building permits, and others, and are known as project permits. All counties and cities,
including those not planning under the GMA, are required to combine the environmental
review process with the project permit review process.
When a fully planning county or city is reviewing a project, its comprehensive plan and
This analysis was prepared by non partisan legislative staff for the use of legislative w
members in their deliberations. This analysis is not part of the legislation nor does it a
constitute a statement of legislative intent.
House Bill Report - 1 - ESHB 1293
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development regulations must serve as the basis for the project permit review. In
determining if a proposed project is consistent with the comprehensive plan and
development regulations, the county or city must consider the type of land use, the level of
development or density proposed, and the availability of infrastructure needed to service the
development. Fully planning counties and cities must comply with additional project
permit processing requirements, including establishing an integrated or consolidated permit
process.
Counties and cities are encouraged to adopt project review provisions to provide prompt,
coordinated review and ensure accountability to applicants and the public, including
expedited review for project permit applications for projects that are consistent with adopted
development regulations and within the capacity of systemwide infrastructure
improvements. Counties and cities also must adopt procedures to monitor and enforce
permit decisions and conditions and may require preapplication conferences or a public
meeting by rule, ordinance, or resolution.
Design Review.
Design review is a formally adopted local government process by which projects are
reviewed for compliance with design standards for the type of use adopted through local
ordinance. Design review focuses on the appearance of new construction, site planning, and
items such as landscaping, signage, and other aesthetic issues. A design element is an
optional element of a comprehensive plan, and many jurisdictions have included design
elements in their comprehensive plans.
Summary:
Design Review.
Beginning six months after its next required periodic comprehensive plan update, a fully
planning county or city may apply only clear and objective regulations to the exterior design
of new development, except for designated landmarks or historic districts established under
a local preservation ordinance. For the design review process, a clear and objective
regulation:
• must include one or more ascertainable guideline, standard, or criterion by which an
applicant can determine whether a given building design is permissible under that
development regulation; and
• may not result in a reduction in density, height, bulk, or scale below the generally
applicable development regulations for a development proposal in the applicable
zone.
Any design review process must be conducted concurrently, or otherwise logically
integrated, with the consolidated review and decision process for project permits, and may
not include more than one public meeting.
Project Review.
House Bill Report - 2 - ESHB 1293
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During project review, counties and cities may only require preapplication conferences or a
public meeting where otherwise required by state law. In addition, counties and cities are
encouraged to adopt project review provisions that ensure an objective review and expedite
project permit applications for projects that include dwelling units that are affordable to
low-income and moderate -income households.
Votes on Final Passage:
House 94 3
Senate 49 0 (Senate amended)
House 95 1 (House concurred)
Effective: July 23, 2023
House Bill Report - 3 - ESHB 1293
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GROWTH MANAGEMENT
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Acknowledgments
Washington State Department of Commerce
Mike Fong, Director
Mark Barkley, Local Government Division, Assistant
Director
Dave Andersen, Growth Management Services,
AICP, Managing Director
Editors
Anne Aurelia Fritzel, AICP, Housing Programs
Manager, Growth Management Services
Catherine McCoy, Senior Planner, Growth
Management Services
Municipal Research and Services Center of
Washington (MRSC) Contributors
Steve Butler, FAICP, Planning & Policy Manager
Ingrid de la Jara, Communications Manager
Jill Dvorkin, Esq., Legal Consultant
Helen Ippolito, Public Policy Intern
Angela Mack, Graphic Designer
Lisa Pool, AICP, Public Policy Consultant
Oskar Rey, Esq., Legal Consultant
Reviewers
This publication was developed with support from
the land use planners of Washington through
Regional Planners' Forums; a panel at the 2022
Washington conference of the American Planning
Association; Washington state agency review from
the Department of Ecology, Department of Health,
Department of Fish and Wildlife, Department of
Natural Resources; and through other engagement
opportunities.
Disclaimer
This publication offers guidance for Washington
local governments in implementing HB 1337 (laws
of 2023) and encourages the creation of new
accessory dwelling units (ADUs). It does not
constitute legal advice, and is not a substitute for
the legal advice of an attorney. Users of this
publication should contact their own legal counsel
regarding their legal rights or any other legal issue.
Also, many of the examples are from current
municipal codes which may not yet be consistent
with the provisions of HB 1337.
Contact
For additional information on the GMA housing
programs, please visit the GMS Planning for
Housing Webpage or contact Anne Fritzel, Housing
Programs Manager:
Anne. Fritzel@a commerce.wa.gov or 360-259-5216
1011 Plum St. SE
P.O. Box 42525
Olympia, WA 98504-2525
www.commerce.wa.gov
For people with disabilities, this report is available
on request in other formats. To submit a request,
please call 360-725-4000 (TTY 360-586-0772)
GUIDANCE FOR ACCESSORY DWELLING UNITS IN WASHINGTON STATE, AUGUST 2023
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Table of Contents
Introduction................................................................................................................................................ 4
Definitions................................................................................................................................................... 5
Legal History of ADU Policy in Washington State.......................................................................................... 6
Requirements for cities and urban growth areas........................................................................................... 8
1. Allow two ADUs per lot......................................................................................................................................... 8
2. Do not require owner occupancy ..............................................
3. Allow separate sale of ADUs.....................................................
4. Set off-street parking requirements consistent with HB 1337
5. Set maximum size limits at no less than 1,000 SF ..................
6. Reduce setbacks for ADUs (especially rear setbacks)............
7. Limit use of design standards ...................................................
8. Allow ADUs of at least 24 feet in height ...................................
9. Reduce impact fees...................................................................
10. Other Fees and Exactions........................................................
12
Recommendations for cities and other urban areas.....................................................................................22
1. Allow prefabricated units....................................................................................................................................22
2. Streamline ADU permitting processes............................................................................................................... 23
3. Offer incentives to encourage ADUs that are affordable to lower -income households ................................ 24
Key considerations for counties..................................................................................................................25
1. Unincorporated UGAs and LAMIRDs.................................................................................................................25
2. Rural and natural resource lands....................................................................................................................... 25
Other programmatic elements to consider..................................................................................................27
1. Address the use of ADUs as short-term rentals................................................................................................ 27
2. Provide user-friendly communication materials...............................................................................................28
3. Provide information on landlord -tenant laws for prospective ADU owners and ADU tenants ...................... 29
4. Provide information on ADU financing and funding programs........................................................................29
5. Create a program to encourage legalization of unpermitted ADUs................................................................ 30
6. Provide pre -approved ADU plans....................................................................................................................... 30
Appendix A: Additional examples and resources.........................................................................................31
Appendix B. Relevant GMHB cases for counties..........................................................................................35
Appendix C. Resources for programmatic elements....................................................................................36
Appendix D: Other ADU information and resources......................................................................................38
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Introduction
Allowing more accessory dwelling units (ADUs) encourages housing construction and increases the overall
supply and variety of housing options, helping address the challenges posed statewide by insufficient housing
HB 1337, passed in 2023, requires jurisdictions to allow two ADUs per lot within urban growth areas (UGAs)
by six months after the next periodic update due date. The Washington State Department of Commerce
(Commerce) presents this publication as an update to the agency's 1994 guidance to assist local governments
in implementing this requirement. The objective is to provide information on the requirements, local policy
choices, and examples of approaches for consideration by cities, towns, and counties, in accordance with the
bill. This guidance is structured into the following sections:
• Requirements for cities and other urban areas.
• Recommendations for cities and other urban areas.
• Key considerations for counties (rural and resource lands).
• Other programmatic elements to consider.
This document provides detail on the state law and local policy choices. Please note that throughout this
document quoted state laws are bolded.
Benefits of ADUs
Construction of new ADUs has many benefits, including to:
• Add to the diversity of housing options.
• Provide a housing type that blends in well with existing low density residential neighborhoods.
• Cater to our state's changing demographics, including more seniors and smaller household sizes.
• Provide housing that is typically more affordable than traditional detached single-family homes.
• Add housing units without expanding urban growth areas.
• Correct historic economic and racial exclusion by opening up single-family neighborhoods to more
diverse housing and household types.
• Reduce climate impacts because ADUs tend to be smaller and use less energy than traditional single-
family homes.
• Use existing infrastructure such as sewer, water and streets.
For these reasons, ADUs can be an effective and "gentle" way of helping to accommodate the state's growing
population.
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Definitions
Local governments should review their development
regulation definitions to ensure consistency with RCW
36.70A.696, as amended. This will help facilitate
consistent implementation of these requirements and
reduce the need for interpretation due to missing or
outdated definitions.
Accessory Dwelling Unit (ADU)
A dwelling unit located on the same lot as a single-
family housing unit, duplex, triplex, townhome or other
housing unit.
Attached ADU
An ADU located within or attached to a single-family
housing unit, duplex, triplex, townhome, or other
housing unit.
Detached ADU
An ADU that consists partly or entirely of a building
that is separate and detached from a single-family
housing unit, duplex, triplex, townhome or other
housing unit and is on the same property.
Dwelling Unit
A residential living unit that provides complete
independent living facilities for one or more persons
and that includes permanent provisions for living,
sleeping, eating, cooking and sanitation.
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Basement attached ADU example, with attached ADU entrance on the side of the structure. Credit: Steve Butler.
Legal History of ADU Policy in Washington State
As required by the 1993 Washington Housing Policy Act, Commerce made recommendations to encourage
development and placement of ADUs, published in 1994 as the Model ADU Ordinance Recommendations. The
Act required cities of over 20,000 population and counties of over 125,000 population, planning under the
Growth Management Act to incorporate the Commerce recommendations into their zoning and development
regulations. To allow local flexibility, the recommendations were subject to local regulations, conditions,
procedures, and limitations.
In 2019, the state Legislature found that Washington State had a housing affordability crisis and sought to
promote and encourage the creation of ADUs. Commerce offered a grant program' to encourage cities to
adopt regulations to increase housing supply, including to: (1) authorize ADUs in one or more zoning district in
which they are currently prohibited; (2) remove minimum parking requirements; (3) remove owner occupancy
requirements; (4) adopt new square footage requirements that are less restrictive than existing requirements;
and (5) develop a local program that offers homeowners a combination of financing, design, permitting or
construction support to build ADUs.2
In 2020, the legislature adopted restrictions on how much off-street parking local governments could require
for ADUs near transit stops. As a result, cities that fully plan under the GMA could not require off-street parking
for ADUs within a quarter mile of a major transit stop, with certain limited exceptions.'
In 2021, the legislature amended RCW 36.70A.070(2)4 to require all cities and counties that fully plan under the
GMA to "consider the role of accessory dwelling units in meeting housing needs." In addition, Section 7 of the
bill stated that cities and counties "should consider" certain policies to encourage the construction of ADUs.
Governor Jay Inslee vetoed this section because it did not specifically limit the policies to lands within urban
This is codified in RCW 36.70A.600.
2 RCW 36.70A.600(1)(n), (o), (p), (q) and (x), passed in 2019, and updated in 2020 to this current list of options.
3 RCW 36.70A.698
4 See HB 1220.
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growth areas. The Governor's veto illustrates a fundamental point: While there is little doubt that local
governments should encourage ADUs in cities and UGAs, very different considerations come into play with
respect to county rural and resource lands.
In 2023, HB 1337 amended RCW 36.70A to add significant changes to local government roles for regulating
ADUs. Within urban growth areas, cities and counties:
• Must allow two ADUs per residential lot. They may be attached, detached, or a combination of both, or
may be conversions of existing structures.
• May not require the owner to occupy the property, and may not prohibit sale as independent units.
• May not charge more than 50% of impact fees charged for the principal unit.
• Must allow an ADU of at least 1,000 square feet and must adjust zoning to be consistent with the bill
for things such as height, setbacks, and other regulations.
• Must set consistent parking requirements based on distance from transit and lot size.
If a city or county does not amend its rules to be consistent with the law, the statute will "supersede, preempt
and invalidate any conflicting local development regulations."'
Other new provisions in HB 1337
• Actions taken by a city or county to comply with new requirements are exempt from legal challenge
under GMA or SEPA.6
• Cities and counties are not required to authorize the construction of an ADU where development is
restricted under rules as a result of physical proximity to on -site sewage system infrastructure, critical
areas, or other unsuitable physical characteristics of a property.'
• Cities and counties may restrict the use of ADUs for short term rentals.$
• Cities and counties may apply public health, safety, building code, and environmental permitting
requirements to an ADU that would be applicable to the principal unit, including regulations to protect
ground and surface waters from on -site wastewater.9
• ADUs are not required to be allowed on lots with critical areas, or around SeaTac airport.10
• Local governments are protected from civil liability if they issue a permit for an ADU on a lot with a
covenant or deed restricting ADUs.11
5 RCW 36.70A.680(1)(b), RCW 36.70A.697(2)
6 RCW 36.70A.680(3)
RCW 36.70A.680(4)
8 RCW 36.70A.680(5)
9 RCW 36.70A.680(5)
10 RCW 36.70A.681(2) and (4)
11 RCW 64.34.120(3)
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Detached ADU/"Carriage House" in Portland. Credit: Radcliffe Dacannay, Radworld (Creative Commons).
Requirements for cities and urban growth areas
1. Allow two ADUs per lot
Allowing ADUs in residential neighborhoods creates additional housing options and gives homeowners greater
flexibility by providing rental income or a place for they or their family members to age in place.
State law
Within urban growth areas, cities and counties must allow two ADUs on all lots in zoning districts that allow
for single-family homes.12 The ADUs may be:
• Two attached ADUs such as unit in a basement, attic, or garage;
• One attached ADU and one detached ADU; or
• Two detached ADUs, which may be comprised of either one or two detached structures.
• A conversion of an existing structure, such as a detached garage.13
When lots are small
Cities and counties must allow an ADU on any lot that meets the minimum lot size required for the principal
unit.14 Minimum lot sizes set the base lot size for development as part of a subdivision process. To support
more ADU development, local governments should reduce or eliminate minimum lot size requirements for
12 RCW 36.70A.681(1)(c)
13 RCW 36.70A.681(1)(i)
14 RCW 36.70A.681(1)(e) states that an ADU must be allowed if the lot meets minimum size for the principal unit. RCW 36.70A.681(3)
states that cities and counties may set a limit of two ADUs, on a residential lot of 2,000 square feet or less. However, if two ADUs are
allowed on lots that meet the minimum lot size, 2,000 SF is not generally going to be a standard lot size and may not have space for
even one ADU.
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ADUs with existing development and allow ADUs on all lots. Where lots are smaller than the minimum allowed
by the zone, cities may choose to rely on the capacity of the lot, sewer, septic, parking, and landscaping or
other regulations to set the limits on one or two ADUs.
Examples
• Enumclaw Municipal Code Sec. 19.34.050: Allows ADUs on lots of any size.
• Kenmore Municipal Code Sec. 18.73.100: Does not require a minimum lot size for ADUs.
• Renton Municipal Code Sec. 4-2-110C: Permits ADUs on lots 3,000 square feet or less.
Restricted development locations
Cities and counties are not authorized to allow construction of ADUs in locations where development is
restricted under other laws, rules, or ordinances due to physical proximity to on -site sewage system
infrastructure, critical areas or other unsuitable physical characteristics of a property.15 This includes critical
areas protection standards, such as buffers and setbacks, as well as associated environmental permitting
review and process requirements. In short, cities and counties should apply the same public health, safety,
building code and environmental permitting requirements to an ADU that would be applicable to the principal
unit, including regulations to protect ground and surface waters from on -site wastewater. The provisions of HB
1337 provide no authority to override local ordinances that address public health and safely.
Cities and counties may restrict ADU development:
• Within areas designated as critical areas (see below).
• In shoreline areas so designated under a shoreline master program (see below).
• On lots in a watershed serving a reservoir for potable water if that watershed is or was listed, as of
July 1, 2023, as impaired or threatened under Section 303(d) of the federal Clean Water Act (33
U.S.C. Sec. 1313(d)).16
• In zones with a density of one dwelling unit per acre or less that are in critical areas, designated as
wetlands, fish and wildlife habitats, flood plains, or geologically hazardous areas." Generally any
zones with such low densities within UGAs are so designated to protect the critical area, so adding
additional development in the form of an ADU is not consistent with this exception.
• Within a mile radius of SeaTac airport."
For areas without sewer
• Cities/counties may prohibit ADUs on properties not served by sewers.
• Septic and related wastewater rules to protect water -quality located in local health codes and 246-272A
and -272B WAC continue to apply to on -site systems for ADUs.
• The Department of Health expects attached ADUs to be more likely to be connected to the same septic
system as the primary single family residence since they are easier to build compliant with Department
of Health rules. The septic system needs to be designed to accommodate this additional wastewater
flow.
• Detached ADUs could, depending on local rules, be served by a separate septic system. The
requirements, including horizontal setback and maximum density requirements of the rule(s) would
apply.
15 https://ecology.wa.gov/Water-Shorelines/Shoreline-coastal-management/Shoreline-coastal-planning/Shoreline-planners-toolbox
16 RCW 36.70A.681(4)
17 RCW 36.70A.680(5)
18 RCW 36.70A.681(2)
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In areas where sewers are likely to be built in the future, plan reviewers may want to take measures to
accommodate the eventual conversion from septic systems to sewer.
Critical areas
Cities and counties shall limit ADU development as necessary to meet critical areas protection standards. All
ADU development must be reviewed for consistency with critical area protection ordinance provisions, and
shall only be allowed when consistent. Critical areas include:
Wetlands, and fish and wildlife habitat conservation areas provide critical ecological functions. They are
protected for their intrinsic values and no additional development is appropriate. Internal conversions of
existing space to an ADU may be permissible, provided all other protections are observed.
Floodplains and geologically hazardous areas are identified as hazard areas that may pose dangers to life
safety and property. Most local jurisdictions allow some development in floodplains and geologically
hazardous areas. However, the development must go through a detailed review process that provides
analysis of the site -specific conditions and the proposed development, supported by reports from certified
experts such as geologists and engineers.
Critical aquifer recharge areas (CARAs), which are important to allow groundwater to recharge aquifers
used for drinking water. In these areas, regulations generally protect against hazardous uses and ensure
impervious surfaces do not restrict groundwater recharge. ADU development over CARAs may be allowed
if it can be demonstrated they will not impact potable water.
While ADUs shall be allowed in residential neighborhoods within the UGA, in geohazard and wetland areas they
must be designed and located to avoid critical area impacts consistent with the mitigation sequence,19 which
includes to:
• Avoid the impact altogether by not taking a certain action or parts of an action.
• Minimize impacts by limiting the degree or magnitude of the action and its implementation by using
appropriate technology, or by taking affirmative steps to avoid or reduce impacts.
• Rectify the impact by repairing, rehabilitating or restoring the affected environment.
• Reduce or eliminate the impact over time through preservation and maintenance operations during the
life of the action.
• Compensate for the impact by replacing, enhancing, or providing substitute resources or environments.
• Monitor the impact and taking appropriate corrective measures.
Reasonable use exceptions
Detached ADUs are not necessary for reasonable residential use within critical areas and should not be
allowed within critical areas or their buffers under reasonable use exceptions. It may be possible to convert
space within existing homes to create an ADU if no new exterior construction, expansion of the footprint or
additional impervious surface is added.
19 https://ecology.wa.gov/Water-Shorelines/Wetlands/Mitigation/Avoidance-and-minimization
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ADUs in shorelines under a shoreline master program
Shorelines and shorelands are governed under the city, town, or
county's Shoreline Master Program (SMP). Although residential uses
are allowed in many shoreline environment designations (SEDs), ADUs
may not be appropriate in all SEDs. The ADU requirements outlined in
HB 1337 are intended to apply within the UGA governed under the
Growth Management Act and are not automatically applicable within
the shoreline jurisdiction governed under the Shoreline Management
Act (SMA). Local governments should plan for ADUs located within
shoreline jurisdiction during a periodic review of their SMP20. Review
and update of an SMP is required every ten years but can be initiated by
a local government outside of the required schedule.
Chapter 90.58 RCW, Chapter 173-26 WAC, and Ecology approved local
shoreline master programs restrict development under SMA goals,
policies, purpose and intent. Within shoreline jurisdiction, zoning code
provisions can be applied, but they must be reviewed in addition to the
bulk, dimensional, performance, and use standards of the SMP, and all
new development and uses, including ADUs, can only be authorized
through the shoreline permitting system outlined in Chapter 173-27
WAC.
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If allowed, ADUs within shoreline jurisdiction shoul
be outside of buffers and setbacks. Credit: Ecology
Each SMP contains residential use regulations and development standards which ensure that allowed uses
and development remain compatible with the shoreline environment and SMP and allow no net loss of
shoreline ecological function. If allowed under the SMP provisions, ADUs would still need to be located outside
of all shoreline buffers and setbacks and would need to meet other SMP critical area, density, impervious
surface, and vegetation conservation provisions.
ADUs are not necessary for reasonable residential use within shoreline jurisdictions and should not be
included as project components in shoreline variance permit applications.
Local governments wanting to address ADUs under the authorities of their SMP should consult Washington
State Department of Ecology guidance2I and work closely with their Ecology shoreline planner.22
Examples
• Black Diamond Municipal Code Sec. 18.56.030 - Allows two ADUs in conjunction with the primary unit
provided adequate provisions for water and sewer are met.
• Langley Municipal Code Sec. 18.08.095 - Allows one attached and one detached ADU on a lot with a
single-family dwelling connected to sewer.
• Burien Municipal Code Sec. 19.17.070 - Permits a maximum of two ADUs (one attached and one
detached) per detached house.
20 The timetable for local governments to develop or amend master programs is required by RCW 90.58.080,
21 https://ecology.wa.gov/Water-Shorelines/Shoreline-coastal-management/Shoreline-coastal-planning/Contacts
22 https://ecology.wa.gov/Water-Shorelines/Shoreline-coastal-management/Shoreline-coastal-planning/Shoreline-planners-toolbox
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2. Do not require owner occupancy
Owner occupancy standards have typically required that a property owner live in either the primary residence or
the ADU, however that may limit the ability of the owner to develop or rent and ADU.
State law
Within UGAs, cities and counties may not require the owner of a lot on which there is an ADU to reside in or
occupy the ADU or another housing unit on the same lot.23 RCW 36.70A.696(9) defines owner as any person
who has at least 50% ownership in a property on which an ADU is located.
Local policy choice
When a unit is used as a short-term rental (STR), a local government may choose to require an owner to
occupy either the primary or an accessory unit. (See the section on short-term rentals.)24
Examples
• Bremerton Accessory Dwelling Units
• Kirkland Accessory Dwelling Units
Seattle Accessory Dwelling Units
• Vancouver Accessory Dwelling Units
3. Allow separate sale of ADUs
Because they are smaller and generally more affordable than most typical single-family homes, sales of ADUs
as separate units can increase homeownership opportunities for first-time homebuyers and low-income
households.
State law
A city or county may not prohibit the sale or other conveyance of a condominium unit independently
of a principal unit solely on the grounds that the condominium unit was originally built as an
accessory dwelling unit.25 Washington's Condominium Act, which provides for the creation of
condominiums, does not preclude ADUs from being created as a part of a condominium development.
Here, the unit is individually owned and the remainder of the property is under common ownership.
Local governments wanting to regulate how ADUs are converted to a condominium form of ownership
should work closely with their legal counsel in reviewing RCW 64.90.025 and other related laws.26
Zero lot line subdivisions and lot splits are mentioned in Section 4(2) of HB 1337, however, there is
currently no authorization for lot splits in Washington, creating true independent units for ADUs. SB
5258 amends RCW 58.17.060 to require all cities and towns to adopt procedures for unit lot
subdivisions to allow division of a parent lot into separately owned unit lots, or owned in common by
the owners of the lots. However, this is better used for developments such as townhouses.
Examples
• Seattle Annual ADU Report 2022 — Addresses ADUs sold as condominiums, highlights the benefits of
ADUs as condominiums and the increase in ADUs as condominiums in Seattle since 2018.
23 RCW 36.70A.681(1)(b)
24 RCW 36.70A.680(5)(a)
25 RCW 36.70A.681(1)(k)
26 See additional information on ADUs and condo's at ADUs and Condos: Separating Ownership I Accessory Dwellings
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• City of Snohomish Unit Lot Subdivision - the city provides a handout with criteria and the process for
unit lot subdivision.
Bellevue unit lot subdivision Web page for townhouses.
4. Set off-street parking requirements consistent with HB 1337
Many lots in established areas aren't large enough to support both an ADU and off-street parking, effectively
prohibiting ADU development. This means that ADUs are often limited to larger lots that can accommodate
parking and other site features. Removing off-street parking requirements for ADUs can help to open up
possibilities for placing ADUs, especially in urban areas with transportation options.
State law
Parking limits for ADUs are subject to the following:
Off street parking may not be required as a condition of permitting ADUs within one half mile of a
major transit stop.27_21
On lots smaller than 6,000 square feet, no more than one off-street parking space may be required
per ADU before any zero lot line subdivisions or lot splits.29
On lots greater than 6,000 square feet, no more than two off-street parking spaces per ADU may be
required before any zero lot line subdivisions or lot splits.
Local policy choice
While on -site parking cannot be required within a half mile of a major transit stop, a city may not want to
require on -site parking in other types of walkable areas or where on -street parking is sufficient. Cities may also
choose to reduce parking requirements from the maximum limits in statute. Because ADUs typically are for
one or two people, no more than one parking space may be needed for any lot size, especially in areas with on -
street parking.
A parking study
Cities may choose to require more parking if Commerce concurs with a locally -conducted empirical study
prepared by a credentialed transportation or land use planning professional that clearly demonstrates that
parking consistent with the law would be significantly less safe for pedestrians, bicyclists, or people in
vehicles than if the jurisdiction's parking requirements were applied to the same location for the same
number of detached houses.30 Commerce is required to develop guidance on the contents of the study by the
end of 2023.
Related to the issue of off-street parking requirements are garage conversions for ADUs. This type of ADU may
be more affordable since the changes are primarily internal to an existing structure, and they're popular with
retirees who want to age in place because they generally have "no -step entries." Because HB 1337 requires
cities to allow garage conversions, and to reduce parking requirements, Commerce recommends that cities
allow any replacement parking for the primary residence and ADU to be on driveways or on the street if
27 Under-RCW 36.70A.681(2), off-street parking for ADUs is prohibited within 1 /2 mile of a major transit stop.
28 Major transit stop is defined in RCW 36.70A.696.
29 This part of statute references zero lot line subdivisions, however, for the purposes of this guidance, this means the ADU is not
subject to primary unit parking requirements, even if subdivided from the primary unit.
30 RCW 36.70A.681(2).
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possible. Low impact development pervious pavement options may be an offset tool to address additional
parking, while also reducing overall site impervious surface area.
Examples
• Fircrest Municipal Code Sec. 22.58.012 - Doesn't require additional off-street parking for ADUs unless the
planning director determines there is insufficient on -street parking to satisfy parking demand.
• Kenmore Municipal Code Sec. 18.73.100 - No additional off-street parking spaces are required for an
ADU.
• Sumner Municipal Code Sec. 18.12.030 - ADUs created via garage conversion are not required to have off-
street parking, as long as there is available on -street parking and the unit is located within half a mile of the
Sumner transit station.
• Kirkland Municipal Code Sec. 115.07 - Doesn't require off-street parking for one ADU. On lots with more
than one ADU, one space is required, with exceptions (available street parking within 600 feet or property is
located within 1 /2 mile of frequent transit).
Smith Gillman Cottage converted garage. Credit: CAST architecture.
5. Set maximum size limits at no less than 1,000 SF
Local governments typically enact maximum size limits for buildings to ensure there is enough space on a lot
for site features like parking and green space. However, maximum size limits that are too restrictive pose
design and use limitations. ADU size limits are typically smaller in urban infill areas than they are for larger
greenfield sites. Some cities and other urban areas set a single maximum that is based on square footage,
while others couple this standard with a percentage of the primary residence.
State law
ADU size limits must allow a gross floor areas of at least 1,000 square feet within UGAs.31 New amendments
to RCW 36.70A.969 define "gross floor area" as the interior habitable area of a dwelling unit including
basements and attics but not including a garage or accessory structure.
31 RCW 36.70A.681(1)(f)
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Examples
• Chelan Municipal Code Sec. 17.20.20 - Limits ADUs in its single-family residential district to 1,200
square feet or no more than 5O% of the total square footage of the primary residence, whichever is less.
The planning director may approve an increased size to efficiently use all floor area if all other
standards are met.
• Kenmore Municipal Code Ch. 18.73 - Attached ADUs are limited to 1,000 square feet unless the ADU is
proposed for preexisting floor area on a single level of the primary unit. For detached ADUs, maximums
are based on lot size.
6. Reduce setbacks for ADUs (especially rear setbacks)
State law
A city or county may not impose setback requirements, yard coverage limits, tree retention mandates,
restrictions on entry door locations, aesthetic requirements, or requirements for design review for ADUs that
are more restrictive than those for principal units."
A city or county must allow detached ADUs to be sited at a lot line if the lot line abuts a public alley, unless
the city or county routinely plows snow on the public alley.33
Setback requirements, which establish the minimum distance from front, side, or rear lot lines, create space
between a building and adjacent uses. Some codes establish setbacks for ADUs that mirror those of the
principal unit, thereby limiting space for ADUs, especially detached ADUs on small lots. Many urban
communities have begun requiring separate, less restrictive setbacks specifically for ADUs. For example, some
cities and other urban areas reduce or waive setbacks for detached ADUs alongside and rear lot lines, and
alleys.
32 RCW 36.70A.681(1)(h).
33 RCW 36.70A.681(1)(i).
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Detached ADU over a garage with relaxed rear setback. Credit: Steve Butler.
Examples
• Bellingham Municipal Code Sec. 20.01.036 — Exempts detached ADUs from side and rear yard
setbacks when abutting an alley.
• LaCenter Municipal Code Ch. 18.247 — Allows detached ADUs at the rear yard lot line if adjacent to an
alley.
Zoning codes should clearly describe ADU standards, which should be at most the same as those for the
primary unit. When ADUs are added on a lot, they should fit on the lot, and be consistent with yard coverage
limits and tree retention provisions. Stormwater low impact development features such as rain gardens and
other bioretention options can be used to define setback areas for an ADU and principal lot, and should be
features to support additional units, rather than be barriers. 34
7. Limit use of design standards
Design standards often involve ensuring ADUs are compatible with the primary residence through features
such as architectural style, window placement, roof form and pitch, and building materials. ADU design
standards, however, can have the unanticipated impact of increasing project costs by lengthening the time
needed for local ADU project review. ADUs can complement, but need not be exactly the same as the principal
unit. Design standards must be clear and objective, should be no more prescriptive than those for single-family
34 Commerce's guidebook: Incentivizing Low Impact Development (LID) Beyond Permit Requirements includes tools and outreach
materials that local governments can utilize to encourage developers to go beyond existing stormwater requirements and help reduce
site impervious areas.
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homes, and may not result in a reduction in density, height, bulk, or scale below the requirements of the
underlying zone.as
State law on design standards
A city or county may not impose setback requirements, yard coverage limits, tree retention mandates,
restrictions on entry door locations, aesthetic requirements, or requirements for design review for ADUs that
are more restrictive than those for principal units."
Local governments should minimize the use of ADU design standards. In some cases, standards may be used
to address privacy, for example making sure that the ADU's windows are located to preserve privacy between
the ADU and neighboring properties or private open space.
HB 1293 (laws of 2023) adds to RCW 36.70A and amends RCW 36.7OB to streamline local design review
processes, requiring "clear and objective" standards that don't reduce development capacity otherwise
allowed. Any design review process must be conducted concurrently, or otherwise be logically integrated, with
the consolidated review and decision process for project permits set forth in RCW 36.7013.120(3). No design
review process may include more than one public meeting. A county or city must comply with these
requirements beginning six months after its next periodic update required under RCW 36.70A.130. The
provisions do not apply to regulations specific to designated landmarks or historic districts established under
a local preservation ordinance
Examples
• Ellensburg Municipal Code Sec. 15.540.040 - Does not require ADUs to match the appearance of the
primary structure.
• Sedro Woolley Municipal Code Sec. 17.100.030 - Allows the planning director to approve interesting
detached ADU designs that are dissimilar from the primary structure.
• Lacey Municipal Code Sec. 14.23.071 - Has minimal design criteria for attached and detached ADUs,
though duplex -like designs are not allowed.
35 RCW 36.70A.630(2). Design review guidelines must provide only clear and objective requirements, such that an applicant can
ascertain whether a particular building design is permissible.
36 RCW 36.70A.681(1)(h).
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ADU in the Wedgewood neighborhood of Seattle. Credit: Pam MacRae, Siahtline Institute. Used with permission.
8. Allow ADUs of at least 24 feet in height
State law
The city or county may not establish roof height limits on an ADU of less than 24 feet, unless the height
limitation on the principal unit is less than 24 feet, in which case, a city or county may not impose roof height
limitation ADUs is less than the height limit that applies to the principal unit.37
Cities and other urban areas typically set building height limits to address issues like views and privacy;
however, they also limit design options and use land less efficiently. Some communities set one height limit
for both the principal unit and ADUs, while others have a separate maximum for ADUs.
Examples
• Kenmore Municipal Code Sec. 18.73.100 - Allows ADUs up to 35 feet.
37 RCW 36.70A.681(1 XW.
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Spokane Municipal Code Sec. 17C.300.130 - Has height limits that are more nuanced and relate to the
proximity of an ADU to a property line.
Larger, taller detached AD — 1130 SF. Credit: Eddie Bojorquez/Crest Backyard Homes.
9. Reduce impact fees
Impact fees
Impact fees are one-time charges assessed by a local government against a new development project to help
pay for new or expanded public capital facilities that will directly address the increased demand for services
created by that development. RCW 82.02.050 authorizes counties, cities, and towns planning under the Growth
Management Act (GMA) to impose impact fees for:
• Public streets and roads;
• Publicly owned parks, open space, and recreation facilities;
• School facilities; and
• Fire protection facilities.
Because ADUs are generally smaller than standard single family homes, they typically have fewer people living
in them, and likely cause fewer impacts.
State law
The city or county may not assess impact fees on the construction of accessory dwelling units that are
greater than 50 percent of the impact fees that would be imposed on the principal unit.38
38 RCW 36.70A.681(1)(al and SIB 5258 (section 10, laws of 2023) amends RCW 82.02.060 to require local governments to publish a
schedule of impact fees which reflects the proportionate impact of new housing units. This includes multifamily and condo units,
based on square footage, number of bedrooms or trips generated, to produce a proportionally lower impact fee for smaller housing
units. Local governments must adopt this schedule within six months after the periodic update due date.
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Local policy choice
Local governments may charge according to the size of the unit, fixture count, or location with the community,
or completely waive fees, but in no case should the fees be more than 50% of what would be charged to the
principal unit.
Examples
• Everett 2023 Impact Fees Schedule — Waives transportation and school impact fees for ADUs.
• Olympia Municipal Code Ch. 15.08 — Waives school impact fees and reduces transportation and park
impact fees for ADUs.
• Renton 2019-2020 Fee Schedule (Section XII) — Provides impact fee reductions and waivers for ADUs
• Lake Stevens Municipal Code Sec. 9.25.010 — Reduces utilities connection fees for ADUs based on
ADU size.
Utility connection fees/system development charges
System development charges, or connection fees may be charged for area -wide improvements for water,
sewer or stormwater. Like impact fees, communities may charge according to the unit's impact on the system.
A fundamental feature of ADUs is that the ADU is "accessory to" a primary residential unit. As a result, the ADU
will be smaller, typically have fewer people living in it, and have a reduced demand for municipal services.
Metering considerations when connecting to the sewer system
The Department of Health considers an ADU a separate dwelling unit if it is located outside and separate from
the single family residence (detached). An ADU located within the single-family residence, such as a basement
or attic unit, is generally not considered a separate connection to the sewer system for the purposes of
metering. The total number of service connections is determined by counting each single-family home, each
dwelling unit in a multi -family building, and each nonresidential building that the water system serves.
Local policy choice
There is no specific requirement to reduce charges for sewer, water and stormwater, as there is for impact
fees, but a local government has the option of removing, reducing or waiving connection fees or system
development charges to meet public purposes. Because of the dependent nature of ADUs, it is recommended
that local governments allow shared meters, especially for attached units that are within the capacity of an
existing meter. There may be limited cases in which separate meters are necessary because of site
configuration or separate sale. They may choose to reduce system development charges to 50% as well
because these charges are meant to fund area wide system development improvements, and an ADU generally
has a smaller impact.
Examples
• King County has a detailed system capacity charge system with charges that vary based on the size
and form of the housing unit, with addition discounts for affordable units.
https://kingcountygov/en/dept/dnrp/waste-services/wastewater-treatment/sewer-system-
services/capacity-charge/about
Kirkland Accessory Dwelling Units — This webpage provides the following information:
ADUs are not subject to water capital facility charges if there are no changes to the water
service/meter.
ADUs are not subject to sewer capital facility charges.
ADUs are not subject to the surface water capital facility charge if the primary residence is already
connected to the public storm system.
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• Olympia Municipal Code Ch. 13.04 and Ch. 13.08 - Provides the option of new connections or tie-ins
when developing an ADU. There is no charge when the connection occurs on the lot. The Olympia
Engineering and Design Standards Section 713.080 addresses the issue of ADUs and side sewers.
• Sedro Woolley Municipal Code Sec. 17.100.030 - Utilities may be shared between an ADU and the
primary dwelling. Sewer connection fees are collected at a reduced rate depending on the size of the
ADU.
10. Other Fees and Exactions
State law
A city or county may not require public street improvements as a condition of permitting ADUs.39
State law requires that public street improvements must not be required as a condition of permitting ADUs,
even if the development of the primary unit can trigger such improvements.
Another barrier might be the cost of permit fees. Local governments often attempt to recoup the actual cost of
processing land use permits, but there is not a legal requirement that they do so. A city or county could choose,
for policy reasons, to charge a lower amount for ADU applications as part of a strategy to encourage property
owners to construct new ADUs on their properties. In addition, lowering fees makes sense if a city or county is
taking other steps to streamline the ADU process, since those measures may also result in lower permit
administration costs.
Example
• Spokane Municipal Code Sec. 08.02.031 - Waived permit fees for ADUs on lots within half a mile of
certain zoning districts. The waiver is set to expire at the end of 2024.
• Washougal Municipal Code Sec. 18.46.020 - Does not charge an application fee for detached ADU
development.
39 RCW 36.70A.681(1)(1). The GMA does not currently define "public street improvements", however "public facilities" is defined in RCW
36.70A.030 and "public improvements" in RCW 39.114.010; both include street and road construction including sidewalks, street and
road lighting systems, storm and sanitary sewer systems, among other public improvements.
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Recommendations for cities and other urban areas
The following recommendations are not required but are suggestions to encourage the development of ADUs
They are to apply only to cities, towns, and other urban areas, including unincorporated urban growth areas
(UGAs) and limited areas of more intensive development (LAMIRDs). The purpose of applying these ADU
recommendations to cities and other urban areas, and not to rural areas or resource lands is to support the
GMA's goals of encouraging development in urban areas and reducing sprawl.
1. Allow prefabricated units
Prefabricated detached ADUs can provide a degree of cost savings, which may make them more affordable for
property owners, especially in more remote areas that may not have access to the tradespeople needed to
construct ADUs. Because materials and manufacturing are centralized at an off -site manufacturing facility,
prefabricated units require less construction time than conventionally built structures and can be constructed
year-round in a climate -controlled factory.
RCW 35A.21.312 allows for consumer choice in housing, requiring local government to allow the placement of
factory -built homes in any location where site -built homes are permitted. The law was likely developed to apply
to primary units, and not necessarily ADUs. However, cities and counties may adopt a set of additional
standards, relating to permanent foundation, roof pitch, and design, although not all of those standards should
be applied to ADUs.
Any prefabricated unit must meet state standards.40 Local codes may refer to larger manufactured homes, and
may not be related to small homes, such as park models, more suitable for an ADU.
Example
• Bremerton Municipal Code Sec. 20.46.010 — Allows for manufactured homes to be used as ADUs
Prefab detached ADU: Nanny Flat, Elder Cottage. Credit: Eddie Bojorquez/Crest Backyard Homes.
40 See the Washington Department of Labor & Industries page on Manufactured Home Permits & Inspections.
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Tiny houses
Tiny houses, or tiny houses with wheels, as defined in RCW 35.21.686, are not generally allowed as ADUs
because they may not meet the standards required for a permanent residential unit, such as a foundation,
water supply and sewage disposal. However, some communities are starting to consider allowing tiny homes
on wheels as temporary units, with appropriate connections and tie-downs.41
One exception in state law is that tiny homes on wheels and RVs may be used as permanent living quarters
only when situated in manufactured/mobile home communities, but they are still subject to certain life/safety
and utility hookup requirements per RCW 35.21.684. Tiny houses must be inspected and meet the standards of
the Washington State Department of Labor and Industry.42
Prefab ADU travelling from factory to residential site / installed on -site. Credit: Roger Fitzsimons.
2. Streamline ADU permitting processes
A local permitting process should be designed to make it as easy as possible for an applicant to prepare and
submit a development permit application, and for the permit review staff to review and quickly approve it. This
approach should be particularly true for the types of development that a community is actively trying to
encourage, such as ADUs.
Discretionary project permitting processes, such as those requiring conditional use permits, hearings examiner
review, and public hearings add extra time and cost to getting a development project approved. These
processes make sense for situations where a proposed project may be large or have a number of potential
41 Port Townsend allows tiny homes on wheels. (THROWS) https://cityofpt.us/planning-community-development/page/new-euly-1 stst-
tiny-house-wheels-thows
42 See the Washington Department of Labor & Industries page on Tiny Houses.
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impacts on a neighborhood or community. For small, low -impact development projects that advance adopted
public policy such as new ADUs, a discretionary permitting process creates an unnecessary barrier to ADU
construction.
Local governments should allow ADUs "by -right," with project review and approval to be done administratively.
Having an expedited or shorter review process for ADUs can also include preferential review of ADU proposals.
Providing pre -approved ADU plans is another method for reducing the time needed to review an ADU proposal
(see provide pre -approved ADU plans below). Streamlining can be additionally bolstered by checklists that
clarify the ADU approval process (see below on providing user-friendly communication materials).
Examples
• Pasco Municipal Code Sec. 25.161.030 — ADU applications are approved administratively.
• Sequim Municipal Code Sec. 18.66.040 — Requires a single administrative permit for ADU development.
The application must be processed by the community development director within 30 days of submittal
(Sec. 20.01.080).
3. Offer incentives to encourage ADUs that are affordable to lower
income households
While ADUs are generally more affordable than a typical single-family home, most aren't affordable to
households making less than 80% of the area median income (AMI). To address this issue, some local
governments offer incentives for ADUs that are affordable for lower -income households (that is, less than 80%
AMI) for a set number of years (such as 50 years). These types of incentives usually involve requiring
affordability in exchange for providing a "bonus," like higher densities in the form of an additional ADU. Local
governments can also support affordability for low-income residents by incorporating ADUs into their
affordable housing funding programs and forming partnerships with community land trusts and other non-
profit organizations.
Local policy choice
There are a number of ways that local governments can offer reductions for affordable housing, most require
some kind of assurance that the unit will remain affordable over time.
RCW 82.02.060(4) also authorizes local governments to offer impact fee reductions or waivers for
affordable housing. An exemption for low-income housing granted under this section, however, must be
conditioned upon requiring the developer to record a covenant that prohibits using the property for any
purpose other than for low-income housing.
RCW 36.70A.540 authorizes local governments to expand affordable housing incentive programs to
include, among other things, fee waivers or exemptions provided the local government is committed to
continuing affordability for at least 50 years.
A local government may offer "tap -in charge" waivers for low-income persons (under RCW 35.92.380 or
RCW 36.94.370).43
Examples
• CLTplusOne — A pilot program offered by Durham (NC) Community Land Trustees, which pairs a land
trust home with ADUs on the same lot. Both the primary residence and rental unit are permanently
affordable (see this Shelterforce article on Durham's Community Land Trust).
43 For more information on this topic, see MRSC's Affordable Housing Techniques and Incentives - Reduction/Waiver of Fees.
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Seattle Municipal Code Sec. 23.44.041 — Allows a second ADU on a lot if one of three conditions are
met: conversion within an existing structure, green building standards, or affordability for "income -
eligible households" for a minimum of 50 years.
Key considerations for counties
GMA-planning counties must plan and provide regulatory frameworks for four land use categories in
decreasing order of ADU intensity:
• Unincorporated UGAs.44
• LAMIRDs
• Rural lands
• Designated natural resource lands
1. Unincorporated UGAs and LAMIRDs
Unincorporated urban growth areas
In unincorporated UGAs, which are generally intended to have urban services and eventually become or annex
into cities, the requirements in this guidance apply within 6 months of the next periodic update.45
LAMIRDs
Within Limited Areas of More Intensive Rural Development (LAMIRDs), the outer boundary may not change, but
the LAMIRD may be filled in with new development, including ADUs.
2. Rural and natural resource lands
ADU regulations outside of urban growth areas require consideration of a different set of factors than ADU
regulations in cities and urban growth areas. ADU provisions in rural and resource areas must be accompanied
by measures to protect rural character, conserve resource lands, and limit density and sprawl.
One of the benefits of ADUs in urban areas is that under HB 1337, the ADUs can be sold separately and add to
the supply of attainable housing for moderate on maybe lower income households. The same does not hold
true in rural areas, where the ADU cannot be sold separately, and the private cost of transportation and public
cost of transportation -related emissions reduces the public benefit of ADUs in rural areas.
When developing or amending regulations, counties should consider the potential for:
• Increased demand for emergency and other services.
• Increased traffic on county roads, which may be built to a lower standard.
• More housing and increased population in areas potentially prone to wildfires or other natural hazards
• Impact on water supplies.
• Conflict with or decrease in land available for agriculture or other natural resource industries.
The Growth Management Hearings Boards (GMHBs) have considered challenges to ADU regulations in rural
and resource designated areas in a handful of counties. Three hearings boards have issued decisions
44 See Chapter 36.70A RCW.
45 RCW 36.70A.680(1)
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disfavoring local regulations allowing detached ADUs where they do not include specific criteria to curtail
indiscriminate increased density.46
Rural lands
For areas designated as "rural," the regulations must be consistent with "rural character" as established in the
rural element of the county's comprehensive plan.47 RCW 36.70A.030(23) defines rural character as "[... j the
patterns of land use and development established by a county in the rural element of its comprehensive plan."
Importantly, what constitutes rural character in one county may be different than what constitutes rural
character in another (RCW 36.70A.011). ADUs should not contribute to sprawl or cause residential uses to
predominate over rural uses.48
Given the need to be consistent with and implement their rural, housing, and land use elements of their
comprehensive plans (among others), it will be important for counties to "show their work" through the written
record, including but not limited to whereas statements, findings of fact, staff reports, and public participation
processes; and to articulate legal and policy justifications for their actions.
Designated natural resource lands
Counties must ensure ADU regulations are consistent with GMA requirements to preserve natural resource
lands for resource production. In natural resource lands, the dominant use is to be the agricultural, forestry, or
mineral use; residential development must be located to not interfere with the natural resource use, and
preserve the majority of land for such use.49 See RCW 36.70A.060.
Considerations and examples for rural and resource areas
Generally, regulations permitting attached ADUs raise fewer concerns than those permitting detached ADUs.
While several counties allow detached ADUs in their rural land designations, most include restrictions related
to standards such as:
• Size limit on a single ADU.
• Minimum lot size to conform to zoning or in some cases, double the minimum lot size.
• Proximity to and dependency on the primary residence (such as shared driveway, parking, yard, septic,
well, utilities, etc.).
• Design standards for consistency with primary unit.
• Limitations on number of permits issued annually.
46 Loon Lake Property Owners, et al v. Stevens County, EWGMHB, Case No. 01-1-0002c, Compliance Order (May 30, 2008); Friends of
San Juans, et al v. San Juan County, Case No. 3-2-0003c coordinated with Nelson, et al v. San Juan County, Case No. 06-2-0024c,
FDO/Compliance Order, at 3 (Feb. 12, 2007).
47 County comprehensive plans must include a rural element. A county's rural element must include policies that are consistent with
rural character. RCW 36.70A.070(5)(0 provides, in relevant part: "[The rural element] shall provide for a variety of rural densities, uses,
essential public facilities, and rural governmental services needed to serve the permitted densities and uses. To achieve a variety of
rural densities and uses, counties may provide for clustering, density transfer, design guidelines, conservation easements, and other
innovative techniques that will accommodate appropriate rural economic advancement, densities, and uses that are not characterized
by urban growth and that are consistent with rural character."
48 RCW 36.70A.020(2) and RCW 36.70A.110(1) and .070 U5. Friends of San Juans, et al v. San Juan County, Case No. 3-2-0003c
coordinated with Nelson, et al v. San Juan County Case No. 06-2-0024c, FDO/Compliance Order, at 3 (Feb. 12, 2007) — Regulations
allowing a detached ADU on substandard rural lots allowed residential use to predominate over rural uses and were therefore
noncompliant; Loon Lake Property Owners, et al v. Stevens County Case No. 01-1-0002C — Allowing an ADU on all parcels —including
substandard lots — can considerably increase density within zone.
49 Futerwise v. Snohomish County, Case 22-3-003, Final Decision and Order. The Board found that the county failed to protect
agricultural lands of long-term commercial significance, in violation of RCW 36.70A.177, and was inconsistent with multi -county and
countywide planning policies, in violation of RCW 36.70A.210.
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• Restrictions on title.
Careful with detached ADUs (attached ADUs preferred)
The hearings boards have held that freestanding residential ADUs should be treated as separate dwelling units
for purposes of density calculations — although in some cases have found compliant county regulations that
allow limited exceptions to detached ADUs triggering such density requirements."
Attached ADUs are Preferred
Conversely, the boards have held that attached ADUs and ADUs converted from an existing structure in close
association with the primary residence (such as a garage) do not count toward density in rural and resource
areas.51
ExampleE
• Clark County: Accessory Dwelling Unit — Rural (Handout) (2022�— Allows only attached ADUs in rural
and resources zones.
• Kitsap County: Accessory Dwelling Unit (Handout) (2022) — Requires detached ADUs to be sited within
150 feet of the principal dwelling outside of UGAs. Size limit, 50% of primary unit or 900 square feet,
whichever is smaller. Owner occupancy requirements and design standards apply.
• San Juan County Code Sec. 18.40.240 — Limits the number of detached ADU permits outside "activity
centers" and UGAs in any calendar year to no more than 12% of the total number of building permits for
new principal residences issued for the previous calendar year. Further limited to one permit per
property owner outside UGAs.
• Spokane County: Detached Accessory Dwelling Unit (Handout_— Detached ADUs in selected rural
zones must be within 150 feet of principal dwelling and meet several other conditions, including that
title notice will be placed on the property that the accessory dwelling may not be sold as a separate
residence until such time as the accessory dwelling is located as the sole residence on a legally
subdivided parcel.
• Walla Walla County Code Sec. 17.08.015 — Requires at least four of six "dependency requirements" be
shared for a detached ADU (road access, septic system, water system, utility meters, yard, and parking
areas).
Other programmatic elements to consider
The following "programmatic elements" are not recommendations but are instead meant to be additional
options to be considered by cities, towns, and other urban areas, including unincorporated UGAs and
LAMIRDS.
1. Address the use of ADUs as short-term rentals
Construction of ADUs presents an opportunity to increase a community's supply of relatively affordable long-
term housing. When an ADU is used as a short-term rental (STR), defined as a housing unit being rented for
fewer than 30 consecutive days, that housing unit functions as a lodging unit for visitors and not as a housing
50 Friends of San Juans, et al v. San Juan County, Case No. 3-2-0003c coordinated with Nelson et al v. San Juan County, Case No. 06-
2,0024c, FDO/Compliance Order, at 3 (Feb. 12, 2007).
51 Yanisch v. Lewis County, Case No. 02-2-0007c, Order on Compliance Hearing (Mar. 12, 2004).
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unit.52 As a result, some local governments completely prohibit the use of ADUs as STRs, while others limit but
don't completely prohibit that use.
The primary rationale for prohibiting or limiting ADUs being used as STRs is that renting an ADU as a long-term
housing unit, defined as being rented for more than 30 consecutive days, will have the dual benefit of providing
a positive income stream to a homeowner and adding a new residential unit to the local housing supply.
Some studies attempt to make the case that ADUs being used as STRs make up "only a small percentage" of
the overall stock of STRs (8%-12%).53 For example, data collected by the City of Seattle shows that 11 % of the
total short-term rental units were ADUs. It should be noted, however, that 11 % still represents 418 units that are
not contributing to that city's long-term housing supply.
Given the significant policy implications, local governments located in areas with high demand for short-term
rentals, such as popular tourist destinations, should carefully consider the pros and cons of allowing ADUs to
be used as short-term rentals.
State law
Cities and counties may restrict the use of ADUs for short term rentals.54
Examples
• Bellingham Municipal Code Sec. 20.10.037 - Does not allow STRs in detached ADUs in single-family
zones but does allow them in detached ADUs in other zones, and in attached ADUs citywide.
• Poulsbo Municipal Code Sec. 18.70.070 - Does not allow ADUs to be used as STRs. Sequim Municipal
Code Ch. 18.66 - Does not allow ADUs to be used as STRs.
2. Provide user-friendly communication materials
To assist applicants in navigating the ADU permitting process, local governments can provide user-friendly
ADU webpages, informational handouts, guides, and checklists. These guidance documents can help by clearly
articulating ADU requirements to property owners, homeowners, contractors, and developers. Clear materials
inform those who are interested in building ADUs and encourage interest in ADU construction.
Examples
• Bremerton Guide to Establishing an ADU (2021 ) - Includes an overview of the city's ADU standards and
links to permit requirements.
• Lake Stevens ADU Permit Checklist - Helps applicants understand the city's ADU provisions.
• Olympia ADUs & Accessory Structures Guide (2022A- Includes an overview of ADU regulations and
standards, including design review requirements and guidelines.
• Seattle ADUniverse: The ABCs of ADUs - Includes a step-by-step guide to creating an ADU.
• Thurston County ADU Handout (20M- Covers the main elements of the county's three -step ADU
permitting process.
52 RCW 36.70A.696(9) defines short-term rental as "a lodging use, that is not a hotel or motel or bed and breakfast, in which a dwelling
unit, or portion thereof, is offered or provided to a guest by a short-term rental operator for a fee for fewer than 30 consecutive nights."
53 See, for instance, the Urban Land Institute's report Jumpstarting the Market for ADUs: Lessons Learned from Portland. Seattle. and
Vancouver.
54 HB 1337 Section 3(W al.
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3. Provide information on landlord -tenant laws for prospective ADU
owners and ADU tenants
For many homeowners renting an ADU on their property, this may be the first time they have served as a
landlord. As a result, they may not be familiar with relevant local, state, and federal laws that apply to landlords
(such as the Fair Housing Act). Conversely, renters also have certain rights and responsibilities under these
laws that both landlords and tenants should know.
The Washington Residential Landlord -Tenant Act includes the state's key landlord -tenant laws." Some local
governments have created landlord -tenant regulations and programs with additional protections for renters,
including rental registration and extra notice of rent increases and/or inspections. To inform both landlords
and tenants about these requirements, local governments can develop user-friendly summaries of these
resources and provide them to ADU applicants during the permit process.
Examples
• Bellingham: Landlords and Tenants — Includes information on the city's rental housing regulations,
rental registration and safety inspection program, and more.
• Benton County: Renter's Resources — Includes information on fair housing and tenant rights in
Washington.
• Burien: Renting in Burien — Includes information on the city's rental housing inspection program, notice
of intent to sell, and eviction law in Washington.
• Olympia: Tenant Protections — Includes information on the city's rental housing ordinance, FAQs, and
more.
• Tacoma: Landlord -Tenant Program — Includes information on the city's landlord -tenant program.
4. Provide information on ADU financing and funding programs
Lack of funding and financing options is often cited as one of the most prevalent challenges for ADU
construction.56 Lending institutions that finance ADU projects generally don't allow homeowners to borrow
against a portion of the future value of an unbuilt ADU, further constraining the viability of projects. To support
homeowners in financing their ADU projects, local governments can:
• Identify other funding and financing opportunities for ADUs and make these resources available at the
permit center and online.
• Develop programs to facilitate access to ADU funding and financing opportunities.
RCW 84.36.400, authorizes counties to provide a three-year property tax exemption for improvements to a
single-family dwelling, including the construction of an ADU, as long as it represents 30% or less of the value of
the original structure. The program was initiated through Chapter 204, Laws of 2020 (2SSB 6231) and
stipulates that dwelling units may be either attached to or within the single-family dwelling or a detached unit
located on the same real property. In 2023, additional provisions were added in King County.s'
55 More information on state and federal laws may be found on the Washington Office of the Attorney General's Landlord -Tenant page
and the U.S. Department of Housing and Urban Development Tenant Rights, Laws and Protections: Washington page.
56 See the UC Berkeley's Terner Center for Housing Innovation's article ADU's for All: Breaking Down Barriers to Racial and Economic
Equity in ADU Construction (2022).
57 SB 5045 offers extended property tax exemptions for ADUs in King County if the unit is affordable.
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ADU owners may deduct, for income tax purposes, construction costs over time, annual property taxes, and
shared monthly utility costs from rental proceeds, which may help encourage their development.
ExampleF
• Olympia OlyFed Bank: ADUs Financing — Provides six loan options for ADU construction. See this ADU
Loan Options flyer and ADU Financing -presentation for more information.
• Spokane Single -Family & Detached ADU Tax Exemption — The City of Spokane highlights the fact that
Spokane County provides a tax exemption for ADUs for the three assessment years after the
completion of the improvement, to the extent the improvement represents 30% or less of the value of
the original structure.
5. Create a program to encourage legalization of unpermitted ADUs
A combination of strong demand for new housing and too many barriers have in some Washington
communities resulted in unpermitted ADUs. Creating a program to allow legalization of unpermitted ADUs can
help promote safe, legal structures and open them up to rental opportunities.
Local governments are encouraged to develop programs to promote the legalization of existing housing units,
which should be done in a manner that ensures ADUs are safe to inhabit.
Examples
• Bellingham Municipal Code Sec. 20.10.036 — Allows ADUs existing prior to January 1, 1995, to become
legally permitted, as long as ADU owners submit an application that is consistent with current ADU
regulations and building codes.
• Ferndale Municipal Code Sec. 18.34.060 — Allows owners of ADUs established before June 20, 2017, to
submit an application to the city to legally permit the existing unit pursuant to the city's ADU
regulations.
6. Provide pre -approved ADU plans
After confirming their property is eligible for an ADU, homeowners begin the design process with an architect
or designer. Depending on whether the unit is within an existing structure or free standing, the design process
can add significant time and expense to a project. To streamline this step, some local governments offer
detached ADU plan designs that have been pre -approved for compliance with building codes. ADU applications
with pre -approved plans are typically approved in a shorter timeframe and with reduced permit fees since the
designs have been vetted by staff. Even though the designs have been pre -approved all other code provisions,
like site -specific standards, still apply.
Examples
• Olympia: Pre -Approved ADU Plans (Guide) (2021) — The cities of Olympia, Lacey, and Tumwater worked
together to offer four plans that have been pre -approved for compliance with building codes.
Leavenworth: ADU Plans — Offers four pre -approved designs. Each option includes two different styles
— modern and traditional.
Renton: Permit Ready ADU Program — Includes eight pre -approved, designed, and engineered model
base plans, ranging in size from 415 to 1,000 square feet and varying in architectural style.
Seattle: Pre -approved Detached ADUs Program — Offers 10 pre -approved plans for detached ADUs,
including factory -assembled structures that have been approved by the Washington Department of
Labor and Industries.
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Cedar Cottage Seattle ADU Pre -Approved Plan (above and below). Credit: CAST architecture.
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Appendix A: Additional examples and resources
1. Allow two ADUs per lot
• Bremerton Municipal Code Ch. 20.46 - Allows up to two ADUs per lot (see Sec. 20.46.010).
• Kirkland Municipal Code Sec. 115.07 - Allows up to two ADUs (either attached or detached).
• Fife Municipal Code Ch. 19.80 - Allows both one attached and one detached ADU on larger city lots.
"For lots between 3,200 and 4,356 square feet, only attached ADUs are permitted. For lots larger than
4,356 square feet both attached and detached ADUs are permitted, provided the extra lot area required
in the applicable zone is met."
• Lake Forest Park Municipal Code Ch. 18.50 - For lots exceeding one acre, one attached and one
detached ADU are permitted (see Sec. 18.50.050).
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2. Do not require owner occupancy
• Seattle Release of Owner Occupancy Covenant for ADUs Forms (Word document) - This form for
recording with the King County Recorder's Office releases property from the covenant for owner
occupancy entered into as a condition of applying for an ADU permit, as owner occupancy is no longer
required by Seattle's Land Use Code per Ordinance No. 125854 (2019).
3. Do not require off-street parking for ADUs
• Bainbridge Island Municipal Code Ch. 18.09 - Allows garage conversions for ADUs.
• Bellevue Ordinance 6589 - Adopted in 2021 prohibiting requirements for off-street parking for ADUs
within one -quarter mile of a major transit stop. For additional background information, see Bellevue's
page on Reduced Minimum Residential Parking Standards.
• Bremerton Municipal Code Sec. 20.46.010 - One ADU is not required to provide an additional off-street
parking space. The second ADU is required, however, to provide an off-street parking space in addition
to that which is required for the principal unit.
• Spokane Municipal Code Sec. 17C.300.130 - No additional parking is required for studio and one -
bedroom ADUs and ADUs within one -quarter mile of certain transit stops. Spokane allows garage
conversion for ADUs.
• Olympia Municipal Code Sec. 18.38.100 - Doesn't require parking spaces for ADUs (see table 38.01,
"Residential" section).
• Tacoma Municipal Code Sec. 13.06.080 - No off-street parking is required for ADUs.
• University Place Municipal Code Sec. 19.70.010 - No additional off-street parking is required for ADUs.
• Vancouver Municipal Code Ch. 20.810 - Doesn't require additional on -site parking in conjunction with
the establishment of an ADU. The city allows conversion of an existing garage structure or other
outbuilding to be converted to an ADU; however, off-street parking for the primary residence is required
to be provided elsewhere on the site.
• Seattle Municipal Code Sec. 23.44.041 - Off-street parking is not required for ADUs, except that an
existing required parking space may not be eliminated to accommodate an ADU unless it is replaced
elsewhere on the lot.
4. Reduce barriers from setbacks and other ADU regulations
Reduce setbacks for ADUs (especially rear setbacks)
• Brier Municipal Code Sec. 17.24.010 - ADUs must conform to standard setback regulations, though the
rear yard setback requirement is reduced to seven feet for ADUs.
• Kirkland Municipal Code Sec. 115.115 - Required setbacks are the same as the underlying zone.
detached ADUs may be located within five feet of an alley. Detached ADUs without alley access may be
located no closer than five feet from the rear property line as long as the portion of the detached ADU in
the reduced setback is no taller than 15 feet.
• Sequim Municipal Code Sec. 18.66.050 - Exempts existing legally created on -site accessory structures
- such as garages - that have been converted to ADUs from complying with setback standards.
• Tacoma Municipal Code Sec. 13.06.080 - No setbacks from alleys are required.
Reduce minimum lot sizes for ADUs (especially on small urban lots)
• La Conner Municipal Code Sec. 15.110.080 - ADUs are allowed on lots that are under 5,000 square
feet.
• Medina Municipal Code Sec. 16.34.020 - ADUs are excluded from minimum lot area requirements.
• Tacoma Municipal Code Sec. 13.06.080 - ADUs are allowed on any legally established lot, regardless
of lot size or width.
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Increase height maximums for ADUs
La Center Municipal Code Sec. 18.247.050 - ADUs are limited in height to 25 feet or the primary
dwelling's height, whichever is lower.
Mukilteo Municipal Code Sec. 17.30.060 - ADUs may be two stories high and must comply with
maximum building heights for the underlying zoning district; Detached ADUs cannot be taller than the
primary unit, except that there is a maximum height of one-story if the detached ADU is located above a
garage or similar structure.
Pacific Municipal Code Sec. 20.92.060 - ADUs may be up to 25 feet high.
5. Increase maximum size limits for ADUs appropriate to zone and context
• Black Diamond Municipal Code Sec. 18.56.030 - Detached ADUs are limited to 1,000 square feet.
• Bremerton Municipal Code Sec. 20.46.010 - Limits ADUs to 1,000 square feet or no more than 60%
percent of the principal unit's total habitable floor area, whichever is greater. Attached ADUs in
residences built prior to 2020 may receive director's approval to increase ADU floor area to equal that
of the principal dwelling.
• Burien Municipal Code Sec. 19.17.070 - Internal or attached ADUs are limited to 1,000 square feet. The
planning director may make exceptions to size limitations to allow for the better utilization of existing
spaces.
• Leavenworth Municipal Code Sec. 18.36.035 - The total habitable floor area of any ADU is limited to
1,200 square feet.
• Kirkland Municipal Code Sec. 115.07 - ADUs are limited to 1,200 square feet.
• Roslyn Municipal Code Sec. 18.140.030 - ADUs are limited to 1,000 square feet.
• Yakima Municipal Code Sec. 15.09.045 - The ADU's floor area is limited to 1,000 square feet.
6. Limit use of design standards
• Bothell Municipal Code Sec. 12.14.135 - Attached ADU entrances are permitted on the front of the
primary residence under certain conditions.
• Bremerton Municipal Code Sec. 20.46.010 - The city has developed a user-friendly ADU Guide (2021)
that summarizes design regulations with visual examples.
• Fife Municipal Code Sec. 19.80.040 - Recommended approaches to promote privacy for adjacent
properties are included in subsection 19.80.040(A)(6).
7. Remove, reduce or waive permit application fees, impact fees, system
development charges, and other ADU-related fees
Utility connection fees/system development charges
• Chelan Municipal Code Sec. 13.33.020 - Offers utility rate reductions for ADUs.
La Center Municipal Code Sec. 18.247.050 - ADUs may share sewer and water connections with the
primary dwelling. System development charges are imposed at a reduced rate compared to a single-
family home (Sec. 18.247.080).
Yakima County Code Sec. 19.18.020 - The ADU and the primary dwelling unit will share a single sewer
and water connection, unless the local sewer and/or water purveyor requires separate connections.
Impact fees
• Bellingham Permit Fees - This webpage offers information establishing that:
• ADUs are assessed at half the multi -family rate for park impact fees.
• For transportation impact fees, the person trip rate is less than duplexes and townhouses
• School impact fees are waived for ADUs.
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• Bellingham Ordinance No. 2018-11-022 - Establishes impact fee reductions related to the city's 2018
ADU code update.
• Kirkland Accessory Dwelling Units - Exempts transportation, park, and school impact fees for ADUs in
accordance with city code (KMC 27.04.050, KMC 27.06.050, KMC 27.08.050). These fees are assessed
on the primary single-family residence only.
• Renton 2023-2024 Fee Schedule - Impact and permit fees are waived for ADUs. Stormwater system
development charges are reduced by 50% for ADUs.
• Tukwila Fee Schedule- Exempts attached ADUs from impact fees (see Figure 16-1 "Fee Schedule").
• Everett 2023 Impact Fees Schedule - Waives traffic and school impact fees for ADUs.
• Olympia Municipal Code Ch. 15.08 - Waives school impact fees and reduces transportation and park
impact fees for ADUs.
• Renton 2019-2020 Fee Schedule (Section XII) - Provides impact fee reductions and waivers for ADUs.
ADU permit application fees
• Port Angeles Temporary Building Permit Fee Waiver Form (2022) - A temporary building permit fee
waiver is available for construction of housing reserved for families with 80% AMI or below through
September 2028; ADUs are included as an acceptable dwelling type for this waiver.
8. Allow prefabricated ADUs
Code examples
• Richland Municipal Code Sec. 23.42.020 - Allows accessory apartment units that are manufactured off
site.
Langley Municipal Code Sec. 18.22.115(C) - While not addressing prefabricated housing, "tiny homes"
are allowed to be used as ADUs, if they can meet the International Residential Code (IRC) and other
specified local standards.
Other resources
• Olympia Manufactured Homes (Handout) (2017) - Manufactured homes are allowed to be used as
ADUs, particularly to promote affordable housing.
Seattle ADUniverse:
• The ABCs of ADUs - Mentions factory -built ADUs in the Construction section.
• Pre -approved Detached ADUs - References factory -assembled structures in the L&I-approved detached
ADUs section. The pre -approved plans include the Urban Cottage Prefab and WOOD Studio design.
• Seattle: Guide to Building a Backyard Cottage (2010) - See page 19.
• Seattle Tip Sheet 305: Factory -Assembled Structures for Residential and Commercial Use (2023) -
Includes a comparison of the three types of factory -assembled structures, local requirements, and fees.
• Insider: A new collection of minimalist tiny homes from $37,500 is available in the US for the first time
(2023) - Article about affordable tiny homes from Latvia -based firm, MyCabin.
• Congress for the New Urbanism: Novel idea - Modular house that's cute (2023) - Article describing a
well -designed modular house that received an Urban Guild Award.
• HUD Office of Policy Development (PD&R): Factory -Built Accessory Dwelling Units for Affordable
Housing Options (2020) - Highlights communities that support factory -built ADU designs.
9. Streamline ADU permitting processes
Code examples
• Olympia Municipal Code Sec. 18.72.080 - Approves ADUs administratively.
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• Pacific Municipal Code Sec. 20.92.057 - Single, straightforward application requirements for ADU
development.
• Sequim Municipal Code Sec. 18.66.040 - Approves ADUs administratively.
• Other resources
• Bellevue: ADU Registration - This webpage notes that ADU registration, a floor plan, and site
sketch/site plan are the minimum necessary to proceed with the ADU application process.
• Camas: ADU Application Form - Two -page application form that includes applicable development
standards and design guidelines.
• Lake Stevens: ADU Compliance Checklist - This checklist provides a detailed overview of the
permitting process.
• MRSC: Streamlining Local Permit Review Procedures - This webpage provides examples of
streamlined permit review processes.
• Seattle: Construction Permit - Addition or Alteration - This webpage provides that to add within an
existing house, a construction addition/alteration permit is needed; to build a detached unit, a
construction addition/alteration permit is needed.
• Vancouver Municipal Code Sec. 20.920.060(H) - Expedites permit review for infill development.
10.Offer incentives to encourage ADUs that are affordable to lower -income
households
• Bellingham Housing Development: Guideline and Procedure Handbook (2019) - Housing Levy funds
are available to support purchases of homes with ADUs.
• Block Project - Nonprofit with a mission to construct and find homeowners in Seattle willing to host an
affordable ADU on their residential properties.
• Habitat for Humanity (Seattle -King & Kittitas Counties) - South Park Project - This award -winning
Habitat for Humanity project, funded in part through Seattle Housing Levy funds, includes ADUs.
• Fannie Mae: HomeReady Accessory Unit Income and Boarder Income Flexibilities (2022) - Expands
access to creditworthy low-income borrowers.
Community land trust (CLT) examples
• National League of Cities: How One Colorado Community Land Trust Is Preserving Homeownership
and Affordability (2021) - Elevation Community Land Trust operates in partnership with a Denver
Housing Authority initiative to support homeowners and prevent displacement. Their approach includes
building ADUs to create more living space for family members or a new source of income.
• T.R.U.S.T. South LA (& four other California CLTs): Increasing Community Power and Health through
Community Land Trusts (2020) - The Community Land Trust Association of West Marin, in
collaboration with the Housing Authority of Marin County, offers zero -interest loans, permit fee waivers,
and other benefits for homeowners to create ADUs for use as affordable rental units.
• Shelterforce: Affordable ADUs: How It's Being Done - Explores pilot programs and other strategies for
financing ADUs for low- and moderate -income homeowners.
Appendix B. Relevant G M H B cases for counties
Futerwise v. Snohomish County, Case 22-3-003, Final Decision and Order. The Board found that the
county failed to protect agricultural lands of long-term commercial significance, in violation of RCW
36.70A.177, and was inconsistent with multi -county and countywide planning policies, in violation of
RCW 36.70A.210.
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• Loon Lake Property Owners Association, et al V. Stevens County, Case No. 01-1-0002c, Compliance
Order (May 30, 2008) — Allowing an ADU on all parcels —including substandard lots-- can considerably
increase density in rural areas; regulations should contain specific criteria to curtail indiscriminate
increased density.
• Friends of San Juans. et al v. San Juan Countv. Case No. 3-2-0003c coordinated with Nelson. et al v.
San Juan County, Case No. 06-2-0024c, FDO/Compliance Order (Feb. 12, 2007) — Regulations allowing
a detached ADU on substandard rural lots allowed residential use to predominate over rural uses and
were therefore noncompliant.
Kittitas County Conservation, et al v. Kittitas County, Case No. 07-1-0015, Final Decision Order (Mar. 21,
2008) — County ADU regulations must contain density provisions to preserve rural character —failure to
do so would result in "urban -like" density in rural areas.
Peninsula Neighborhood Association v. Pierce County, Case No. 95-3-0071, Final Decision and Order
(Mar. 20, 1996) — Local governments are required to include ADU provisions in their development
regulations, but those regulations must be consistent with the GMA requirement that local
governments reduce sprawl in rural areas.
• Yanisch v. Lewis County, Case No. 02-2-0007c, Order on Compliance Hearing (Mar. 12, 2004) — County
definition of "rural character" must comply with GMA; subdivision or sale of ADU to family member may
not be approved if doing so creates lots of less than five acres.
Appendix C. Resources for programmatic elements
1. Address the use of ADUs as short-term rentals
• La Conner Municipal Code Sec. 15.110.080 — ADUs may not be used as short-term rentals.
• Langley Municipal Code Sec. 5.40.030 — A maximum of 50 ADUs can be used as short-term rentals in
Langley.
• Marysville Municipal Code Sec. 22C.180.030 — ADUs aren't permitted as short-term rentals.
• Roslyn Municipal Code Sec. 18.140.030 — ADUs may be rented for a minimum of 60 days.
• Tukwila Municipal Code Sec. 18.50.220 — Doesn't allow ADUs to be rented for periods of less than 30
days.
2. Provide user-friendly communication materials
• Bellingham: Homeowner's Handbook to Building an ADU — This handbook, developed by the Whatcom
Housing Alliance and the City of Bellingham, includes ADU basics and information on permitting,
design, construction, and costs.
• Jefferson County: The ABCs and 123s of ADUs (2022) — This guide, developed by the Housing
Solutions Network, includes information for homeowners considering ADU development, particularly for
affordable housing.
• Lynnwood ADU Guide — One -page guide with an overview of the city's ADU requirements, including
those related to size, design, and setbacks.
• Poulsbo Accessory Dwelling Units — This webpage includes ADU basics, benefits of an ADU, code
requirements, permitting process, handouts, and flow charts.
• Redmond ADU (Handouty(2019) — This one -pager includes an overview of the city's ADU requirements
and permit process.
• San Juan County Detached ADU Permit Application Checklist (2018) — One -page overview of all permit
application requirements.
• Seattle: A Guide to Building a Backyard Cottage (2010)
Spokane Accessory Dwelling Unit Current Allowances (2022) — Includes quick facts.
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Tacoma ADU Tip Sheet (2022) - Includes development standards, permit requirements, submittal and
review process, and more.
Tacoma Accessory Dwelling Units Design Guide (2022) - A handbook for building ADUs.
Toronto, Canada
• Changing Lanes - Laneway Suites in the City of Toronto - Provides requirements, reports, and other
information for laneway suites (i.e., detached ADUs abutting a public laneway).
• Garden Suites - Offers rules and regulations, key considerations, and other information for garden
suites (i.e., detached ADUs that do not about a laneway).
• YouTube - City of Toronto Garden Suites Draft Rules - Video discussing the city's draft rules for garden
suites.
• Vancouver ADU Fact Sheet (2022) -Includes FAQs.
3. Provide information on landlord -tenant laws for prospective ADU owners and ADU
tenants
• A Regional Coalition for Housing (ARCH): Renting Out An ADU - Information on finding tenants, rental
agreements, landlord -tenant relationship, and more in East King County.
• Bellevue: Residential Rental Regulations - Contains general guidelines for ADU rental terms.
• Kenmore Ordinance No. 22-0545 (2022) - Adopts tenant protections increasing notice for rent
increases, capping late fees, capping move in fees and deposits, and more. The ordinance notes that
"dwelling unit" has the same meaning as the state's Residential Landlord -Tenant Act (RCW 59.18.030),
which defines it as "...a structure of that part of a structure which is used as a home, residence, or
sleeping place by one or two or more persons maintaining a common household..."
• Kirkland: Tenant Protections - Includes new tenant protections related to notice of rent increases,
maximum security deposit, and enforcement.
• Redmond: Living in Redmond - Includes information on the city's new tenant protections.
4. Provide information on ADU financing and funding programs
• Fannie Mae: HomeReady Accessory Unit Income and Boarder Income Flexibilities (2022) - Expands
access to creditworthy low-income borrowers.
• Freddie Mac: Accessory Dwelling Unit (ADU) FAQ - Includes common questions about Freddie Mac's
ADU loan terms.
• UC Berkeley's Terner Center for Housing Innovation & USC's Lusk Center for Real Estate: ADU
Construction Financina (2022) - Includes product examples and considerations.
• A Regional Coalition for Housing (ARCH): ADU Lending Assistance - Includes information about both
private and public financial requirements and assistance.
• Local Investing Opportunities Network (LION) - Provides loans for ADU development in Jefferson
County.
5. Provide information on ADU condominium conversions
Bellevue ADU Reform Land Use Code Amendment (LUCA) - The city is updating its code to remove
barriers for the construction of attached ADUs, including removing the prohibition on condominium
conversion.
7. Create a program to encourage legalization of unpermitted ADUs
Code examples
• Burien Municipal Code Sec. 19.17.070 - ADUs without city approval may be legalized if the owner
applies for the applicable permits.
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• Enumclaw Municipal Code Sec. 19.34.240 - Allows ADUs that existed as of November 1, 2001, to be
legally established with an application, inspection, and affidavit. Permit application fees were waived
within the first year of the relevant ordinance being in effect.
• Kirkland Municipal Code Sec. 115.07 - An ADU inspection is required for issuance of an ADU permit if it
was built without a final building permit.
• Langley Municipal Code Sec. 18.22.115 - An ADU that existed as of January 22, 2019, may be legally
established and may continue to be used as an ADU with an application, inspection, and affidavit.
• Mukilteo Municipal Code Sec. 17.30.040 - ADUs built without proper permitting may become legal if
the owners submit an application and fulfill parking and owner occupancy requirements, among others.
• Newcastle Municipal Code Sec. 18.31.050 - ADUs may become legal following an application and
inspection process.
• Roslyn Municipal Code Sec. 18.140.030 - If an ADU was created without a building permit, the city
requires a building inspection to determine if the structure is sound, will not pose a hazard to people or
property, and complies with the ADU requirements and building code.
Other resources
• Casita Coalition: Legalizing an Unpermitted ADU (2022) - Provides guidelines for homeowners to
legalize existing ADUs.
• Seattle: Construction Permit - Establishing Use - This webpage provides that to legalize an existing
unit, a construction permit is needed to establish use: additionally, there could be a need to apply for
electrical service changes or new services from Seattle City Light.
Seattle Department of Construction and Inspections
• Tip 217 - How to Legalize a Use Not Established by Permit (2022) - Includes the rationale for applying
for a permit to establish a use and how to document a use for the record.
• Tip 606 - Illegal Dwelling Units (2022) - Defines illegal dwelling units and the process to legalize or
remove them.
8. Provide pre -approved ADU plans
• Lacey Accessory Dwelling Units - Four pre -approved detached ADU plans are available.
• Raleigh. INC: ADU Fast Track Gallery-- Provides ADU plans at a lower cost than typical design
processes.
Appendix D: Other ADU information and resources
Definitions
RCW 36.70A.696 - Provides statutory definitions.
Seattle Office of Planning & Community Development: Encouraging Backyard Cottages - This webpage
includes definitions for detached and attached ADUs.
• Vancouver Municipal Code Ch. 20.810 - See Sec. 20.810.020 for ADU definition.
Adopting ordinances
Bremerton Ordinance No. 5410 (2020) - Amends section 20.46.010, in response to HB 1923 (2020).
Bremerton Ordinance No. 5416 (2021) - Adopts amendments to the city's ADU regulations, including
increasing minimum size, removing parking requirements, removing owner occupancy requirements,
and changing design standards.
Langley Ordinance No. 1051 (2019) - Amends several sections of the Langley Municipal Code,
including section 18.22.155, to encourage housing options and increase housing affordability.
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• Seattle Ordinance (2019) — Amends multiple sections of the Seattle Municipal Code to remove barriers
for attached and detached ADUs and add a floor area ratio requirement in certain single-family zones.
Spokane Ordinance No. C36225 (2022)— Amends multiple sections of the Spokane Municipal Code to
increase flexibility for ADUs. Changes to the ADU regulations were a Washington State Department of
Commerce grant deliverable.
Tacoma Ordinance No. 28576 (2019) — Amends multiple sections of the Tacoma Municipal Code to
allow detached ADUs in single-family zones, simplify regulatory requirements, reduce regulatory
barriers, and increase flexibility in building design, size and location.
See also the pre -amble to early versions of HB 1337, which provides a number of finding support ADU
ordinances.
Code reform processes
• Bellevue ADU Code Reform — The city's land use code amendment will remove barriers and encourage
the construction of attached ADUs.
• Everett ADU Amendments — Includes project documents for process to simplify ADU regulations.
• Policies in housing and comprehensive plans
• Burien Comprehensive Plan: Chapter 2 - Plan Policies (2022) — See the housing element (2.4) goals
specifically focused on ADUs: Pol. HS 1.3, Pol. HS 1.10 and Pol. HS 1.11.
• Everett Housing Action Plan (2021) — ADUs are noted as a key strategy to increase housing variety. See
section related to ADUs: "Increasing Housing Variety" Recommendation 1.1.
• Kent Housing Options Plan (2021) — See information related to ADUs in page 71 (Table 5.3) and pages
146148.
• Langley Comprehensive Plan (2018) — See land use (LU), housing (H), and utilities and capital facilities
(UCF) goals and policies related to ADUs: LU-4.8, H-1.1, H-4.1, H-4.4, and UCF-1.3.
• Olympia Housing Action Plan (2021) — ADUs are a key implementation strategy for increasing the
variety of housing choices (see Chapter 2: Strategy 4).
• Seattle 2035 Comprehensive Plan (2020) — See the policies related to ADUs: Land Use (LU) policy LU
7.5, Greenwood/Phinney Ridge (G/PR) housing policy G/PR-P11, Queen Anne (QA) policy QA-P13,
Wallingford (W) housing policy W-P14, and Westwood Highland Park (W/HP) housing policy W/HP-P21.
• Spokane Comprehensive Plan - Housing Chapter (2017) — See H 1.19 (Senior Housing), H 1.20 (ADUs).
Regional and national reports and websites
• accessorydwellings.org — A one -stop source about ADUs, multigenerational homes, laneway houses,
ADUs, granny flats, and in-law units.
• American Association of Retired Persons (AARP): All About Accessory Dwelling Units — Free
publications, and more, about how ADUs expand housing options for people of all ages.
• American Planning Association (APA): Accessory Dwelling Units — Webpage with reports, briefing
papers, articles, case studies, videos, and more.
• A Regional Coalition for Housing (ARCH): Accessory Dwelling Unit — A comprehensive, user-friendly
website from an affordable housing partnership organization focused on serving East King County.
• MRSC: Accessory Dwelling Units — Webpage that provides a good summary about ADUs.
• Puget Sound Regional Council Housing Innovations Program: Accessory Dwelling Units (2020) — Guide
that includes an overview of ADUs in the Puget Sound region, along with model policies and
regulations.
• Shelterforce: ADUs - Laws and Uses, Do's and Don'ts — Summary of some key debates pertaining to
ADU rentals.
• University of Toronto: "The Citizen Developer" video (YouTube -- Short video discussing the benefits of
small-scale housing.
a
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./►' Washington State
Department of
140 Commerce
We strengthen communities
User Guide for
Middle Housing Model
Ordinances
January 26, 2024
GROWTH MANAGEMENT SERVICES
v3.0
3.d
Acknowledgements
Washington State Department of Commerce
Mike Fong, Director
Mark Barkley, Local Government Division, Assistant Director
Dave Andersen, Growth Management Services, AICP, Managing Director
Editors
David Osaki, AICP, Middle Housing Lead
Anne Aurelia Fritzel, AICP, GMS Housing Programs Manager
Mary Reinbold, AICP, Senior Planner, Growth Management Services
Content Development
Bob Bengford, AICP, Partner, MAKERS Architecture and Urban Design
Scott Bonjukian, AICP, Project Manager, MAKERS Architecture and Urban Design
Ian Crozier, AICP, Associate Planner, MAKERS Architecture and Urban Design
Markus Johnson, Planner, MAKERS Architecture and Urban Design
Clay White, AICP, Planning Director, Kimley-Horn
Ben Felstein, Planner, Kimley-Horn
Tyler Bump, Partner, ECONorthwest
Mackenzie Visser, Associate, ECONorthwest
Michelle Anderson, Project Manager, ECONorthwest
Sara Springer, Member, Ogden Murphy Wallace PLLC
Drew T. Pollom, Ogden Murphy Wallace PLLC
Shane Hope, Principal, Plan Hope
Technical Committee
Preston Frederickson, City of Walla Walla
Mark Hofman, City of Newcastle
Erin Fitzgibbons, City of Newcastle
Joyce Phillips, City of Olympia
Elise Keim, City of Shoreline
Salina Lyons, City of Covington
Dafne Hernandez, City of Covington
Rob White, City of Ruston
Washington State Department of Commerce
PO Box 42525
Olympia, WA 98504-2525
www.commerce.wa.gov
Spencer Gardner, City of Spokane
David Boyd, City of Bothell
Rebecca Samy, City of Bothell
Nick Bond, City of Port Orchard
Adam Weinstein, City of Kirkland
Becky Ableman McCrary, City of Everett
Brennon Staley, City of Seattle
Carl Schroeder, Association of Washington Cities
For people with disabilities, this report is available on request in other formats. To submit a request, please call
360-725-4000 (TTY 360-586-0772). Published January 26, 2024.
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Table of Contents
1.0 - Introduction........................................................................................................................................ 4
1.1 - Applicability...................................................................................................................................................... 7
1.2 - Statutory Compliance Deadlines..................................................................................................................10
1.3 - How To Use the Model Ordinances..............................................................................................................11
2.0 - Model Ordinances and Annotations...................................................................................................14
Introduction..............................................................................................................................................................14
Ordinance Recitals ...............................................
2.1 - Purpose.......................................................
2.2 - General Provisions ......................................
2.3 - Definitions...................................................
2.4 - Applicability.................................................
2.5 - Unit Density and Affordable Housing ........
2.6 - Middle Housing Types ................................
2.7 - Dimensional Standards ..............................
2.8 - Design Standards.............
2.9 - Parking Standards ...........
2.10 - Infrastructure Standards
....................................15
....................................17
....................................18
.................................... 20
.................................... 24
.................................... 28
34
38
48
60
65
3.0 - Additional Considerations................................................................................................................. 68
3.1 - Existing Zones and Overlay Zones............................................................................................................... 68
3.2 - Major Transit Stops....................................................................................................................................... 69
3.3 - Declarations and Governing Documents.....................................................................................................73
3.4 - State Environmental Policy Act(SEPA)........................................................................................................74
3.5 - Building Code.................................................................................................................................................74
3.6 - Critical Areas..................................................................................................................................................74
3.7 - Subdivisions...................................................................................................................................................76
4.0 - Integration with Other State Law Requirements.................................................................................
77
4.1 -
HB 1337 and Accessory Dwelling Units.......................................................................................................77
4.2 -
SB 5258 and Unit Lot Subdivisions...............................................................................................................78
4.3 -
HB 1220 and Housing Elements...................................................................................................................82
4.4 -
Land Use Elements and Land Capacity........................................................................................................
84
4.5 -
SB 5058, SB 5258, and Condominium Buildings.........................................................................................87
4.6 -
SB 5235 and "Family„ Definition...................................................................................................................87
4.7 -
SB 5258 and Impact Fees.............................................................................................................................
88
4.8 -
Shoreline Master Programs and Regulations..............................................................................................89
5.0 - Affordable Housing...........................................................................................................................
91
5.1 -
Development Feasibility Analysis.................................................................................................................91
5.2 -
Alternatives to HB 1110 Affordability Requirements..................................................................................96
6.0 - Alternative Compliance.....................................................................................................................
98
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6.1 - Alternative to Density Requirements.....
6.2 - Alternative Local Action .........................
Appendix A - Middle Housing Pro Forma Assumptions............................................................................. 105
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1.0 - Introduction
User Guide Purpose
This User Guide is intended to support planners, advisory bodies, elected officials, and interested parties in
implementing code amendments related to RCW 36.70A.635 and related RCW sections, and to help the
readers understand the organization and basis for recommended standards in the middle housing model
ordinances. The User Guide uses diagrams, references to public informational documents, and real -world
examples to offer recommendations and best practices for the development of middle housing.
Background
The Washington Legislature passed Engrossed 2nd Substitute House Bill 1110 ("E2SHB 1110", commonly
referred to as "HB 1110") in 2023. HB 1110 requires 77 jurisdictions across the State of Washington to adopt
development regulations allowing for middle housing on all lots zoned predominantly for residential use,
including minimum unit per lot standards, maximum parking requirements, and requiring administrative design
review in cases where design review is used. The main provisions of HB 1110 are codified in RCW 36.70A.635
through RCW 36.70A.638.
In passing HB 1110, the Legislature's findings are:
"...Washington is facing an unprecedented housing crisis for its current population and a lack
of housing choices, and is not likely to meet the affordability goals for future populations. In
order to meet the goal of 1,000,000 new homes by 2044, and enhanced quality of life and
environmental protection, innovative housing policies will need to be adopted.
Increasing housing options that are more affordable to various income levels is critical to
achieving the state's housing goals, including those codified by the legislature under chapter
254, Laws of 2021.
There is continued need for the development of housing at all income levels, including middle
housing that will provide a wider variety of housing options and configurations to allow
Washingtonians to live near where they work.
Homes developed at higher densities are more affordable by design for Washington residents
both in their construction and reduced household energy and transportation costs.
While creating more housing options, it is essential for cities to identify areas at higher risk of
displacement and establish antidisplacement policies as required in Engrossed Second
Substitute House Bill No. 1220 (chapter 254, Laws of 2021).'
The state has made historic investments in subsidized affordable housing through the housing
trust fund, yet even with these historic investments, the magnitude of the housing shortage
requires both public and private investment.
In addition to addressing the housing shortage, allowing more housing options in areas
already served by urban infrastructure will reduce the pressure to develop natural and
1 Department of Commerce guidance for implementing House Bill 1220: https://www.commerce.wa.gov/serving-communities/growth-
management/growth-management-topics/planning-for-housing/updating gma-housing-elements/
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working lands, support key strategies for climate change, food security, and Puget Sound
recovery, and save taxpayers and ratepayers money."
RCW 36.70A.636(2)(a) directs the Washington State Department of Commerce ("Department of Commerce")
to "...(p]ublish model middle housing ordinances no later than six months following July 23, 2023." The Model
Ordinances and User Guide have been written to carry out this directive. Importantly, the Model Ordinances are
not a duplication of the law and are written with the understanding that a "model" is a good example or
recommendation. The Model Ordinances and User Guide offer guidance to create increased housing capacity,
promote housing production, increase densities, ensure functional and livable developments, protect the
environment, and encourage the development of housing affordable at different income levels.
The Model Ordinances are designed to assist cities with implementing new middle housing requirements and
advancing supportive zoning for middle housing. This includes addressing topics such as reasonable
dimensional standards and other provisions which will facilitate middle housing development. Local
jurisdictions may make adjustments to these standards and provisions based on their local policy priorities.
The User Guide offers guidance on options for cities to address HB 1110 requirements, code changes to
implement these new requirements, and a suite of recommendations so that development regulation
amendments work well when implemented.
The Department of Commerce hired a consultant team for the overall body of work. The Model Ordinances and
User Guide were shaped by engagement with stakeholders along with the project team's expertise in middle
housing policy, land use planning, development regulations, and economic analysis.
Benefits of Middle Housing
Middle housing has many benefits, including:
• Contributing to undoing historic economic and racial exclusion by opening up traditionally single-family
neighborhoods to more diverse housing options and household types.
• Providing housing that is typically more affordable both in their construction costs and reduced household
energy and transportation costs than traditional detached single-family homes.
• Supporting efforts to address climate change, by expanding housing types that generally have less
environmental impact per unit and lower carbon footprints than a detached single-family home.
• Providing housing that complements transit and walkability.
• Focusing new housing in urban areas and limiting the conversion of farms, forests, and rural lands.
• Contributing to meeting new Housing Element requirements by providing more housing for people at
different income levels.
For these and other reasons, middle housing is an effective way to help accommodate housing needs for the
state's growing population.
General Considerations
Effective implementation of HB 1110 requires thoughtful amendments to development regulations. How those
amendments are drafted will vary given that cities have various code frameworks for how their zoning and
other development regulations are organized and administered. For example, to regulate use some cities rely
on a comprehensive use table, while others list allowed uses by zone. To regulate bulk some cities use floor
area ratio (FAR), others do not.
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While cities subject to HB 1110 likely have already seen some middle housing development, infill development
of middle housing on typical lots in existing neighborhoods may be new. Under HB 1110 cities cannot require
lot sizes for middle housing which are more restrictive (larger) than for detached single-family residences.
Development standards that work well for middle housing on larger lots may preclude infill development on
smaller lots. The User Guide recommends approaches to evaluate code amendments in a manner that reduces
s
barriers to the development of middle housing types, especially on small infill lots.
a
In amending development regulations for middle housing, cities should review their development regulations
for potential barriers to middle housing. Facilitating middle housing development is an important step in
demonstrating how Housing Element requirements are being met (RCW 36.70A.070(2)(d)). While RCW
36.70A.635(6)(b) below establishes a guardrail for middle housing requirements, applying the statutory
requirement literally such that existing detached single-family regulations apply to middle housing may not
result in codes that will allow middle housing development,
"(b) Except as provided in (a) of this subsection, any city subject to the requirements of this section... shall not
require through development regulations any standards for middle housing that are more restrictive than
those required for detached single-family residences, but may apply any objective development
regulations that are required for detached single-family residences, including, but not limited to, set -back,
lot coverage, stormwater, clearing, and tree canopy and retention requirements to ensure compliance
with existing ordinances intended to protect critical areas and public health and safety. " (RCW
36.70A.635(6)(b))
The Model Ordinances and this User Guide do not address every possible development situation that could
apply to middle housing. Below are some questions that may assist cities in determining whether their code
actively accommodates middle housing (some are expanded upon later in the User Guide):
• Do established building setbacks, especially rear setbacks, need to be modified to accommodate
development on small lots?
Do current road standards account for the need for narrow driveways to access development on the rear of
a lot if the primary home is retained, or if new middle housing development occurs on a vacant lot? Will
there typically be enough room between the retained home or new middle housing development and the
side property line?
Are there subdivision standards which require large landscape buffers?
These may be appropriate for traditional low -density single-family
subdivisions but could be challenging to implement for infill
subdivisions with middle housing.
Allowing middle housing types widely across cities is a step towards
realizing the benefits associated with these housing types. However, how
middle housing development standards are drafted and adopted, along with
other considerations such as fee structures and infrastructure can impact
the outcomes of allowances. This User Guide seeks to provide information
and guidance for jurisdictions to assist in developing and adopting middle
housing regulations that can efficiently bring middle housing to the market
in a manner compatible with surrounding development.
Zoning
Zoning is just one of many types of
regulations that control development.
Source: MAKERS
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1.1 -Applicability
Of the 281 cities and towns in Washington, 77 are subject to the requirements of RCW 36.70A.635. Only cities a)
which are within "fully planning" counties under the Growth Management Act are subject to RCW 36.70A.635, N
and only then if the city also meets additional qualifying criteria. The statute uses 2020 Washington State
Office of Financial Management (OFM) data to identify cities initially subject to the statute.2
The statute describes three categories of cities, primarily based on population but one category also accounts
for whether a city is or is not within a contiguous urban growth area with the largest city in a county, if the
county is more than 275,000 in population. For the purposes of the Model Ordinances and this User Guide, the
Department of Commerce references these categories as "tiers." The tiers are:
• Tier 1: Cities with a population of at least 75,000
• Tier 2: Cities with a population of at least 25,000 but less than 75,000
• Tier 3: Cities with a population less than 25,000, located in a county with a population of more than
275,000, and in a contiguous urban growth area with the largest city in the county
The list of cities subject to RCW 36.70A.635 follows.
Tier 1 Cities
These are cities with a population of at least 75,000 in 2020.
City
Seattle
City 2020 Population
(U.S. Census)
737,015
228,989
City 2023 Population
Estimate (OFM)
779,200
Spokane
232,700
Tacoma
Vancouver
219,346
190,915
222,400
199,600
Bellevue
151,854
154,600
Kent
136,588
139,100
Everett
110,629
114,200
Renton
Spokane Valley
106,785
107,900
102,976
107,400
Federal Way
101,030
102,000
Yakima
96,968
98,650
Kirkland
92,175
96,920
Bellingham
Auburn
Kennewick
91,482
95,960
87,256
88,820
83,921
86,470
Pasco
77,108
81,280
2 Office of Financial Management population data for 2020: https://ofm.wa.gov/washington-data-research/population-
demographics/population-estimates/historical-estimates-april-1-population-and-housing-state-counties-and-cities
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Tier 2 Cities
These are cities with a population of at least 25,000 but less than 75,000 in 2020.
City
Redmond
City • i Population
73,256
170,714
67,455
63,612
City 2023
•.. •
77,490
73,780
68,280
64,150
63,320
Marysville
Sammamish
Lakewood
Richland
60,560
Shoreline
58,608
61,120
Olympia
55,382
56,900
Lacey
53,526
59,430
Burien
52,066
52,560
Bothell
48,161
43,505
49,550
Bremerton
Puyallup
44,640
43,420
42,973
Edmonds
42,853
43,370
Issaquah
40,051
41,290
Lynnwood
38,568
40,790
Lake Stevens
35,630
35,575
41,260
Wenatchee
35,850
Mount Vernon
35,219
35,590
University Place
34,866
35,580
Walla Walla
34,060
34,310
Des Moines
32,888
33,260
31,740
29,250
SeaTac
31,454
Maple Valley
28,013
Camas
26,065
27,420
Mercer Island
25,748
25,800
Tumwater
25,573
27,100
Moses Lake
25,146
26,210
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Tier 3 Cities
3.d
These are cities with a population less than 25,000 in 2020, located in a county with a population of at least
275,000, and in a contiguous urban growth area with the largest city in the county. Those counties and their
largest cities are the following:
'
King
LargestPopulation
Seattle
Tacoma
Everett
2,269,675
920,393
County 2023 Populati
•
2,347,800
946,300
859,800
554,600
Pierce
Snohomish
827,957
Spokane
Spokane
539,339
Clark
Vancouver
503,311
527,400
Thurston
Olympia
Bremerton
294,793
275,611
303,400
283,200
Kitsap
The list of Tier 3 cities follows.
Kenmore
'
King
King
City 2020 Population
23,914
21,798
21,538
21,286
City 2023 Population
•
24,230
22,780
21,590
23,810
21,630
Tukwila
Mukilteo
Mountlake Terrace
Mill Creek
Snohomish
Snohomish
Snohomish
20,926
Covington
King
20,777
21,600
Arlington
Snohomish
19,868
21,740
Washougal
Port Orchard
Lake Forest Park
Woodinville
Clark
17,039
15,587
13,630
13,069
17,490
Kitsap
King
17,480
13,660
King
13,830
DuPont
Pierce
10,151
10,180
Newcastle
King
13,017
13,610
Edgewood
Liberty Lake
Pierce
Spokane
12,327
13,590
12,003
13,150
Fife
Pierce
10,999
11,150
Airway Heights
Spokane
10,757
11,280
10,800
Sumner
Pierce
10,621
n
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Milton
Pacific
King/Pierce
King/Pierce
Pierce
City 2020 Population
(U.S. Census)
8,697
7,235
City 2023 Population
Estimate (OFIVI)
8,715
7,270
7,235
6,840
Fircrest
7,156
6,771
Normandy Park
King
Steilacoom
Pierce
6,727
6,825
Brier
Black Diamond
Snohomish
6,560
6,610
6,880
King
4,697
Algona
King
3,290
3,315
Clyde Hill
King
3,126
3,115
Medina
King
2,915
2,925
Millwood
Spokane
Snohomish
King
1,881
1,925
Woodway
1,318
1,340
Yarrow Point
1,134
1,135
Ruston
Pierce
1,055
1,065
Hunts Point
King
457
317
460
315
Beaux Arts Village
King
1.2 — Statutory Compliance Deadlines
HB 1110
RCW 36.70A.635(11)(a) and (b) state that a city must comply with the requirements of RCW 36.70A.635 the
latter of:
Six months after the city's next periodic comprehensive plan update required under RCW 36.70A.130 if the
city meets the population threshold based on the 2020 Office of Financial Management population data; or
12 months after the city's next implementation progress report required under RCW 36.70A.130 after a
determination by the Office of Financial Management that the city has reached a population threshold
established under RCW 36.70A.635(1).
When a city moves into a new population tier it must comply with the applicable requirements of RCW
36.70A.635 no later than one year after the next implementation progress report required under RCW
36.70A.130. Implementation progress reports are due five years after the review and revision required by of
their comprehensive plan required under RCW 36.70A.130.
For example:
The city of Redmond, which is currently Tier 2, crossed the 75,000 population threshold after 2020. The city
will need to comply with Tier 1 requirements 12 months after its next implementation progress report
required under RCW 36.70A.130.
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The city of Bainbridge Island, which is currently not subject to the requirements of HB 1110 based on its
2020 population, crossed the 25,000 population threshold after 2020. The city will need to comply with Tier
2 requirements 12 months after its next implementation progress report required under RCW 36.70A.130. ;
Other Bills
This User Guide references several other 2023 housing bills or sections of state law that apply compliance
deadlines. These are summarized below.
• HB 1337 (accessory dwelling units): Fully -planning cities and counties must effectuate the requirements
of RCW 36.70A.680 and .681 beginning six months after the next periodic comprehensive plan update
required under RCW 36.70A.130.3
• HB 1293 (design review): Fully -planning cities and counties must effectuate the requirements of RCW
36.70A.630 beginning six months after the next periodic comprehensive plan update required under RCW
36.70A.130.4
• SB 5258 (impact fees): Fully -planning cities and counties must effectuate the requirements of RCW
82.02.060(1) six months after the next periodic comprehensive plan update required under RCW
36.70A.130.5
• SB 5258 (unit lot subdivisions): All cities, counties and towns are to adopt procedures for unit lot
subdivisions by the next periodic update required under RCW 36.70A.130.6
1.3 — How To Use the Model Ordinances
Model Ordinance Text
The Department of Commerce's authority to publish this Model Ordinance is provided in RCW 36.70A.636(2)(a)
and (b), which state:
"(2) (a) The department shall publish model middle housing ordinances no later than six months following
July 23, 2023.
(b) In any city subject to RCW 36.70A.635 that has not passed ordinances, regulations, or other official
controls within the time frames provided under RCW 36.70A.635(11), the model ordinance
supersedes, preempts, and invalidates local development regulations until the city takes all actions
necessary to implement RCW 36.70A.635."
The Model Ordinances have two text styles meant to address HB 1110 implementation:
Bold text in the Model Ordinances represents provisions from RCW 36.70A.635 that cities subject to the
law must implement.
The non -bold text are standards that are optional for a city to use. Cities may choose to revise these
optional standards, as well as adopt all, some, or none of the optional provisions. However, the non -bold
text will apply to a city that does not pass ordinances, regulations, or other local controls to implement
House Bill 1110 within the time frame required by RCW 36.70A.635(11), until such time the city takes all
3 RCW 36.70A.680(1)(a)
4 RCW 36.70A.630(5)
5 RCW 82.02.060(10)
6 RCW 58.17.060(3)
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actions necessary to implement RCW 36.70A.635. Certain optional standards are included in the Model
Ordinance for this specific reason, to allow a city to have basic standards for certain middle housing types
(such as cottage housing) should the Model Ordinance temporarily be in effect.
The diagram below summarizes the scenarios in which this Model Ordinance applies.
Scenario 1
City adopts regulations
complying with HB 1110
by its deadline*
Bold text is integrated
(required by HB 1110)
Non -bold text is optional
Scenario 2
City has not adopted regulations
complying with HB 1110
by its deadline*
Bold text is in effect
(required by HB 1110)
Non -bold text is in effect
Later, after the deadline, city
adopts regulations complying
with HB 1110
Bold text is integrated
(required by HB 1110)
Non -bold text is optional
* Deadline is six months after a city's next periodic comprehensive plan update required by RCW 36.70A.130
Example Section
In some cases, required provisions of HB 1110 have been rewritten for ease of use and to translate the law into
local code format with the same effect. For example, for Tier 2 cities, RCW 36.70A.635(1)(a)(i) states:
(1) Except as provided in subsection (4) of this section, any city that is required or chooses to plan under
RCW 36.70A.040 must provide by ordinance and incorporate into its development regulations, zoning
regulations, and other official controls, authorization for the following:
(a) For cities with a population of at least 25,000 but less than 75,000 based on office of financial
management population estimates:
(i) The development of at least two units per lot on all lots zoned predominantly for residential
use, unless zoning permitting higher densities or intensities applies;
This requirement for Tier 2 cities is written in the Model Ordinance as:
A. The permitted unit density on all lots zoned predominantly for residential use is:
1. Two units per lot, unless zoning permitting higher densities or intensities applies.
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The Two Model Ordinances
The two Model Ordinances are similar. One is for Tier 1 and 2 cities, and the other is for Tier 3 cities. The key
differences are listed in the table below.
Middle Housing Types
Base Unit Per Lot Density
Additional Unit Per Lot
Density
At least six of nine middle housing
building types must be allowed*
Tier 1
4 units per lot**
Tier 2
2 units per lot**
Tier 1
6 units per lot when near major transit or
when at least 2 affordable housing units
are provided**
Tier 2
4 units per lot when near major transit or
when at least 1 affordable housing unit is
provided**
Floor Area Ratio Progressive standards based on unit per
lot count
Maximum Lot Coverage
Minimum Setbacks
Design Standards
Lot coverage maximum is higher than the
Tier 3 Model Ordinance and is based on
unit per lot count
At least four of nine middle housing
building types must be allowed, subject to
review by the city's attorney
2 units per lot**
No additional units per lot required
No FAR standard
Lot coverage maximum is lower than the
Tier 1 and 2 Model Ordinance
The minimum rear setback is less than in The minimum rear setback is higher than
the Tier 3 Model Ordinance I in the Tier 1 and 2 Model Ordinance
Design standards are included. Less
standards are included in Tier 1 and Tier 2
cities than for Tier 3 cities (e.g., there are
no standards in Tier 1 and Tier 2 for
covered entries and window/door
transparency).
Design standards are included. More
standards are included in Tier 3 cities than
for Tier 1 and 2 cities.
* RCW 36.70A.635(5) requires a city to allow "at least" six of the nine middle housing types. The model
ordinance allows all nine to avoid pre -judging which middle housing types the jurisdiction intends to allow in
the event the model ordinance goes into effect for jurisdictions that do not meet the statutory deadline to
adopt middle housing regulations.
** RCW 36.70A.635(1) uses the phrase "at least" when describing these unit per lot standards. Cities can allow
higher unit per lot densities.
Tier 1: Cities with a population of at least 75,000. Tier 2: Cities with a population of at least 25,000 but less
than 75,000.
2 Tier 3: Cities with a population less than 25,000, located in a county with a population of more than 275,000,
and in a contiguous urban growth area with the largest city in the county.
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2.0 - Model Ordinances and Annotations
Introduction
User Guide Chapter 2.0 copies most of the Model Ordinances' text (for all city tiers) and adds supplemental
annotations. The annotations provide context, options, and recommendations for particular topics. Note:
Model Ordinances sections as well as excerpts from existing RCWs are italicized throughout this document
Annotations are organized under the following headings:
• Local Policy Choice — Describes code options cities could consider to achieve desired local outcomes,
including developing more housing.
• Discussion — Describes reasoning for model code content, issues cities should consider when drafting the
middle housing development regulations, and recommendations for cities that want to consider code
amendments that go beyond the minimum requirements of HB 1110.
• References — Provides citations and links to research, articles, local codes, and real -world examples.
• Footnotes — Footnotes on the Model Ordinance provisions provide additional resources and clarifications.
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Ordinance Recitals
Model Ordinance Text
The Model Ordinance text is copied below for reference.
ORDINANCE NO. XXXX
AN ORDINANCE OF THE CITY/TOWN OF WASHINGTON, IMPLEMENTING THE
REQUIREMENTS OF ENGROSSED SUBSTITUTE HOUSE BILL (E2SHB) 1110, ADDING NEW
SECTIONS AMENDING SECTIONS PROVIDING FOR
SEVERABILITY, AND ESTABLISHING AN EFFECTIVE DATE.
WHEREAS, in 2023 the Washington State legislature passed Engrossed Substitute House Bill (E2SHB) 1110
(chapter 332, Laws of 2023) related to middle housing; and
WHEREAS, in passing E2SHB 1110 (chapter 332, Laws of 2023) the State legislature found that Washington
is facing an unprecedented housing crisis for its current population and a lack of housing choices, and is not
likely to meet affordability goals for future populations; and
WHEREAS, the State legislature further found that in order to meet the goal of 1,000,000 new homes
statewide by 2044, and enhanced quality of life and environmental protection, innovative housing policies
will need to be adopted and that increasing housing options that are more affordable to various income
levels is critical to achieving the state's housing goals, including those established by the legislature in
Engrossed Second Substitute House Bill No. 1220 (chapter 254, Laws of 2021); and
WHEREAS, the State legislature further found:
There is continued need for the development of housing at all income levels, including middle housing
that will provide a wider variety of housing options and configurations to allow Washingtonians to live
near where they work;
Homes developed at higher densities are more affordable by design for Washington residents both in
their construction and reduced household energy and transportation costs;
While creating more housing options, it is essential for cities to identify areas at higher risk of
displacement and establish anti -displacement policies as required in Engrossed Second Substitute
House Bill No. 1220 (chapter 254, Laws of 2021);
The state has made historic investments in subsidized affordable housing through the housing trust fund,
yet even with these historic investments, the magnitude of the housing shortage requires both public and
private investment;
and
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In addition to addressing the housing shortage, allowing more housing options in areas already served by
urban infrastructure will reduce the pressure to develop natural and working lands, support key strategies
for climate change, food security, and Puget Sound recovery, and save taxpayers and ratepayers money.
WHEREAS, on _ the city/town council passed Ordinance No. __ _ incorporating middle
housing policies into the Housing Element of the Comprehensive Plan as required by House Bill 1220
(chapter 254, Laws of 2021); and
WHEREAS, on _ the city/town transmitted a copy of the proposed ordinance to the
Washington State Department of Commerce in accordance with RCW 36.70A.106 at least 60 days in
advance of adoption for the required 60-day State review period; and
WHEREAS, on _ the city/town issued a State Environmental Policy Act (SEPA) Determination
of Non -Significance (DNS) on the proposed ordinance, which is a non -project proposal: and
WHEREAS, during the course of developing the proposed ordinance, various means of public outreach were
used including, but not limited to, public meetings, a middle housing webpage, presentations at various
community groups, notification of public hearings; and
WHEREAS, the city/town planning commission held work sessions on to study and review matters
related to implementing ES2HB 1110; (chapter 332, Laws of 2023) and
WHEREAS, on the city/town Planning Commission held a duly noticed public hearing on the
proposed ordinance, accepted testimony and made a recommendation to the _ —city/town council; and
WHEREAS, on the city/town council held a duly noticed public hearing to consider the
planning commission recommendation and accept public testimony; and
WHEREAS, adoption of the ordinance will bring the city/town into compliance with ES2HB 1110 (chapter
332, Laws of 2023) and will serve the general welfare of the public;
NOW THEREFORE BE IT ORDAINED BY THE CITY/TOWN COUNCIL AS FOLLOWS
Discussion
These are example recitals. Recitals serve to support findings of fact, purpose and background information
related to passage of an ordinance. Cities may tailor their recitals as much as necessary to reflect local
ordinance structure, conditions and process.
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2.1 — Purpose
Section 1 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 - How To
Use the Model Ordinances for information on the difference between bold text and non -bold text.
The purpose of this middle housing ordinance ("ordinance') is to:
A. Implement Engrossed Second Substitute House Bill 1110, codified in RCW 36.70A.030, 36.70A.280,
36.70A.635, 36.70A.636, 36.70A.637, 36.70A.638, 43.21 C.495, and 43.21 C.450, 64.32, 64.34, and 64.38, and
64.90, by providing land use, development, design, and other standards for middle housing developed on all
lots zoned predominantly for residential use.
B. If necessary, supersede, preempt, and invalidate the city's development regulations that conflict with this
ordinance until such time the city takes all actions necessary to implement RCW 36.70A.635, if the city has
not taken action necessary to implement RCW 36.70A.635 by the time frame required by RCW
36.70A.635(11). The model ordinance shall remain in effect until the city has taken all necessary actions to
implement RCW 36.70A.635. 1
Discussion
These are example purpose statements. A city adopting development regulations for middle housing by the
statutory deadline for complying with RCW 36.70A.635 does not need to include the purpose statement in
Model Ordinance Section 1, Subsection (B), since the city will already be complying with the statute.
7 RCW 36.70A.636(2)
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2.2 - General Provisions
Section 2 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
A. Nothing in this ordinance prohibits the city from permitting detached single-family residences.8
B. Nothing in this ordinance prohibits the city from requiring any development, including middle housing
development, to provide affordable housing, either on -site or through an in -lieu payment, nor limit the city's
ability to expand or modify the requirements of an existing affordable housing program enacted under RCW
36.70A.540.9
C. Nothing in this ordinance requires the issuance of a building permit if other federal, state, and local
requirements for a building permit are not met.10
D. Nothing in this ordinance affects or modifies the responsibilities of the city to plan for or provide "urban
governmental services" as defined in RCW 36.70A. 030. 11
E. The city shall not approve a building permit for middle housing without compliance with the adequate water
supply requirements of RCW 19.27.097.12
F. The city shall not require through development regulations any standards for middle housing that are more
restrictive than those required for detached single-family residences, but may apply any objective
development regulations that are required for detached single-family residences, including, but not limited
to, set -back, lot coverage, stormwater, clearing, and tree canopy and retention requirements to ensure
compliance with existing ordinances intended to protect critical areas and public health and safety. 13, 14
G. The same development permit and environmental review processes shall apply to middle housing that
apply to detached single-family residences, unless otherwise required by state law including, but not
limited to, shoreline regulations under chapter 90.58 RCW, building codes under chapter 19.27 RCW,
energy codes under chapter 19.27A RCW, or electrical codes under chapter 19.28 RCW.15
8 RCW 36.70A.635(g)
9 RCW 36.70A.635(2)(c), RCW 36.70A.635(3)
10 RCW 36.70A.635(10)
11 RCW 36.70A.638(9) and (11)
12 RCW 36.70A.638(10)
13 RCW 36.70A.635(6)(b)
14 Definition of "development regulations" under RCW 36.70A.030(13): "Development regulations" or "regulation" means the controls
placed on development or land use activities by a county or city, including, but not limited to, zoning ordinances, critical areas
ordinances, shoreline master programs, official controls, planned unit development ordinances, subdivision ordinances, and binding
site plan ordinances together with any amendments thereto. A development regulation does not include a decision to approve a project
permit application, as defined in RCW 36.7013.020, even though the decision may be expressed in a resolution or ordinance of the
legislative body of the county or city.
15 RCW 36.70A.635(6)(c)
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H. Conflicts. In the event of a conflict between this ordinance and other development regulations applicable to
middle housing, the standards of this ordinance control.
Discussion
Items in bold above are general provisions included in HB 1110. General provisions apply to the ordinance as a
whole and provide clarifying information on how it is implemented.
Model Ordinance Section 2, Subsection (1) regarding conflicts, is included because the Model Ordinance
cannot account for every existing development regulation a city may apply to middle housing.
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2.3 — Definitions
Section 3 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
The following definitions shall apply for the purposes of this ordinance, notwithstanding other definitions in the
city's development regulations:16
Administrative design review" means a development permit process whereby an application is reviewed,
approved, or denied by the planning director or the planning director's designee based solely on objective
design and development standards without a public predecision hearing, unless such review is otherwise
required by state or federal law, or the structure is a designated landmark or historic district established under
a local preservation ordinance. A city may utilize public meetings, hearings, or voluntary review boards to
consider, recommend, or approve requests for variances from locally established design review standards.
"All lots zoned predominantly for residential use" means all zoning districts in which residential dwellings are the
predominant use. This excludes lands zoned primarily for commercial, industrial, and/or public uses, even if
those zones allow for the development of detached single-family residences. This also excludes lands zoned
primarily for mixed uses, even if those zones allow for the development of detached single-family residences, if
the zones permit by -right multifamily use and a variety of commercial uses, including but not limited to retail,
services, eating and drinking establishments, entertainment, recreation, and office uses.
"Cottage housing" means residential units on a lot with a common open space that either: (a) Is owned in
common, or (b) has units owned as condominium units with property owned in common and a minimum of 20
percent of the lot size as open space."
"Courtyard apartments" means up to four attached dwelling units arranged on two or three sides of a yard or
court. "18
"Development regulations" means any controls placed on development or land use activities by the city,
including, but not limited to, zoning ordinances, official controls, subdivision ordinances, and binding site plan
ordinances.
"Duplex" means a residential building with two attached dwelling units.
"Fiveplex"means a residential building with five attached dwelling units.
Tourplex" means a residential building with four attached dwelling units.
16 RCW 36.70A.030
17 See design standards for cottage housing in Section 2.8 of the Model Ordinances.
18 See design standards for courtyard apartments in Section 2.8 of the Model Ordinances.
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"Major transit stop" means a stop on a high capacity transportation system funded or expanded under the
provisions of chapter 81.104 RCW, commuter rail stops, stops on rail or fixed guideway systems, and stops on
bus rapid transit routes.11 W�
"Middle housing" means buildings that are compatible in scale, form, and character with single-family houses
and contain two or more attached, stacked, or clustered homes including duplexes, triplexes, fourplexes,
fiveplexes, sixplexes, townhouses, stacked flats, courtyard apartments, and cottage housing.
"Single-family zones" means those zones where single-family detached residences are the predominant land
use.
"Sixplex"means a residential building with six attached dwelling units.
"Stacked flat" means dwelling units in a residential building of no more than three stories on a residential
zoned lot in which each floor may be separately rented or owned.
"Tier 1 city" means a city with a population of at least 75,000 based on 2020 Office of Financial Management
population estimates.
"Tier 2 city" means a city with a population of at least 25,000 but less than 75,000 based on 2020 Office of
Financial Management population estimates.
"Tier 3 city" means a city with a population of less than 25,000, that is within a contiguous urban growth area
with the largest city in a county with a population of more than 275,000, based on 2020 Office of Financial
Management population estimates.
"Triplex" means a residential building with three attached dwelling units.
"Townhouses" means buildings that contain three or more attached single-family dwelling units that extend
from foundation to roof and that have a yard or public way on not less than two sides.20
"Unit density" means the number of dwelling units allowed on a lot, regardless of lot size.21
Discussion
All Lots Zoned Predominantly for Residential Use
RCW 36.70A.635(1) applies the middle housing unit per lot standards to "all lots zoned predominantly for
residential use". The Model Ordinance recommends a definition of this phrase to help cities determine where
the Model Ordinance should apply."
19 See User Guide Section 3.2 for more information on major transit stops.
20 A "yard" refers to any type of open space on the lot adjacent to a building and does not refer to regulated setbacks. A "public way"
refers to any public or private street, alleys, pathways, or similar feature which the public has a right of use.
21 The User Guide may also refer to unit density as "unit per lot."
22 The phrase "lots in the city that are primarily dedicated to single-family detached housing units" is also used in RCW 36.70A.635(4)(a)
when discussing the alternative to density requirements. The phrase is not defined in the GMA or in the Model Ordinance. Additional
guidance on this phrase, however, may be found in Chapter 6.1 as it relates to the alternative density option.
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RCW 36.70A.635(1) does not specify whether it is intended to apply unit per lot requirements to lots created in
the future. However, the plain language of the word "all" implies the whole amount of lots are subject to RCW
36.70A.635(1), which includes all lots that currently exist and all lots created in the future. See User Guide
Chapter 2.5 for information on multifamily zones which may be excluded from this definition in certain
circumstances.
Unit Density
Unit density is defined to refer to the number of units on a lot. RCW 36.70A.635 (5) does state that cities "may"
allow accessory dwelling units to achieve the unit density requirements of RCW 367.70A.635(1). Cities
choosing to count accessory dwelling units as part of "unit density' and adopting the term "unit density" in
local code should consider a definition that makes reference to accessory dwelling units. See more
information in User Guide Chapter 4.1.
Middle Housing Building Types
Only four the nine middle housing building types are defined in statute. Cities should define duplex, triplex,
fourplex, fiveplex and sixplex. The following examples illustrate the need for cities to carefully consider how
their "plex" definitions are written:
A three-story stacked flat building (with one unit per floor) could also be considered a triplex.
A four -unit courtyard apartment building could be considered a fourplex building.
A townhouse -style building with six units on a single lot (as opposed to each townhome being on its own
lot) could also be considered a sixplex.
While some overlap in definitions is reasonable as long as the effect of state law is met, distinctions are
helpful for applicants and city staff. Cities need to consider how different middle housing types are treated to
comply with RCW 36.70A.635(5), which requires, in part, that "A city must allow at least six of the nine types of
middle housing to achieve the unit density required." A city's code should specifically identify which of the six
types of middle housing (or more than six if a city chooses to allow more than six) is permitted. Clear
definitions of those middle housing types that are permitted by the city is also necessary for applicable design
standards. For example, a four -unit courtyard apartment building requires a court or yard, but a fourplex
building does not.
However, while different middle housing types may allow the same number of units, the four middle housing
types that are defined in statute (RCW 36.70A.030) have distinguishing building form characteristics. Cities
should consider these definitions, as defined in statute. For example:
Cottage housing requires common open space, and open space that is a minimum of 20 percent of the lot
size (RCW 36.70A.030(9)). Although the "Cottage housing" definition could be read such that the 20
percent open space requirement only applies to condominium units with property owned in common, this
User Guide recommends the same 20 percent apply to all cottage housing development. From a land use
standpoint, the form of ownership should not determine the open space percentage for the residents.
Courtyard apartments have a yard or court surrounded on two or three sides by dwelling units. They are a
maximum of four units for the purpose of meeting the requirements of RCW 36.70A.635 (RCW
36.70A.030(10)). Some cities define or promote courtyard apartments already; such buildings designed
with fully -enclosed courtyards or more than four dwelling units could be classified as another middle
housing type such as a sixplex or a larger multifamily use.
Townhouses are a minimum of three units and are "...attached single-family dwelling units..." (RCW
36.70A.030(41)). Some cities allow townhouse buildings to be a minimum of two units.
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Stacked flats have each floor separately owned or rented (RCW 36.70A.030(40)). Because the definition
limits stacked flat buildings to "three floors" such buildings can only have two or three units.
Major Transit Stop
See discussion of major transit stops, including future major transit stops not yet in operation, in Chapter 3.2.
Also note that the definition of a "Major transit stop" for accessory dwelling units, under RCW 36.70A.696(8), is
different definition of than the general definition of "Major transit stop" in HB 1110 (RCW 36.70A.030(26).
Multifamily
The provisions of RCW 36.70A.635 control for middle housing regardless of the local definition of
"multifamily".
For example, consider a Tier 1 city that currently defines "multifamily" as three or more units. Zone A is zoned
predominantly for residential use, and in the zone detached single-family residences are permitted and
multifamily is prohibited. Middle housing with three or four units cannot be prohibited in Zone A.
In another example, consider a city that defines "multifamily" as three or more units and which requires
multifamily uses in Zone B to include a minimum landscaped area but does not have the same requirement for
detached single-family residential uses in Zone B. Any middle housing uses with three or more units in Zone B
meeting the definitions in RCW 36.70A.030 and the Model Ordinance are not subject to the minimum
landscaped area requirements because middle housing cannot be treated more restrictively than detached
single-family uses in the same zone.
References
• "A Planners Dictionary", American Planning Association
• Growth Management Act definitions — RCW 36.70A.030
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2.4 — Applicability
Section 4 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
A. The provisions of this ordinance shall apply to all lots zoned predominantly for residential use.23
B. The provisions of this ordinance do not apply to:"'
1. Lots designated with critical areas designated under RCW 36.70A.170 or their buffers as required by
RCW 36.70A.170.25
2. A watershed serving a reservoir for potable water if that watershed is or was listed, as of July 23, 2023,
as impaired or threatened under section 303(d) of the federal clean water act (33 U.S.C. Sec.
1313(d)).26
3. Lots that have been designated urban separators by countywide planning policies as of July 23, 2023.
Local Policy Choice
Applicable Zones
The list of zoning districts applicable to RCW 36.70A.635
will be based on the local jurisdiction's evaluation of which
zoning districts fall under the term "all lots zoned
predominantly for residential use." The Model Ordinance
definition recommends that this include single-family and
multifamily zones in which residences are the predominant
use. However, the unit density and allowed use standards
in Model Ordinance Section 5 and 6 do not apply to zoning
districts "permitting higher densities or intensities", than
the densities prescribed in RCW 36.70A.635.
Middle housing can reach surprisingly high densities. For
example, on a 5,000 square foot lot, two units are
Cities should not assume existing multifamily zones are
exempt from RCW 36.70A.635. Source: MAKERS
23 Because the Model Ordinances apply automatically to cities which do not meet the compliance deadline for RCW 36.70A.635, the
Model Ordinances do not include a placeholder for a city to list applicable city zoning districts subject to RCW 36.70A.635(1). Each
city will need to work within the framework and structure of its own zoning code to identify which zoning districts are characterized by
"lots zoned predominantly for residential use". Cities have the option to list the specific zone names in ordinances adopting local
regulations which implement RCW 36.70A.635. See more information under Local Policy Choice.
24 RCW 36.70A.635(8)
25 RCW 36.70A.170
26 More information on impaired and threatened watersheds can be found through the Department of Ecology:
https://ecology.wa.gov/Water-Shorelines/Water-quality/Water-improvement/Assessment-of-state-waters-303d
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approximately 18 units per acre, and four units are approximately 35 units per acre. Cities should not assume
existing multifamily zones are exempt from RCW 36.70A.635, and should evaluate the densities that middle
housing can achieve under applicable minimum lot sizes and other zoning standards. Where a city has
established a "true" multifamily zone that is intended for high -densities and multifamily use, cities can consider
setting a minimum unit density or unit per acre that is higher than can be achieved by middle housing while still a
complying with RCW 36.70A.635(5).27 Mixed -use zones which permit by -right multifamily and a variety of a
commercial uses are not subject to RCW 36.70A.635.28 0
Alternative Compliance
Cities may implement an alternative density requirement option in RCW 36.70A.635(4) that applies the
standards of RCW 36.70A.635(1) to a different set of lots than "all lots zoned predominantly for residential
use". The alternative to density requirements in RCW 36.70A.635(4)(a) applies to "lots in the city that are
primarily dedicated to single-family detached housing units", and contain specific requirements that must be
met.
Another available alternative action is based on addressing requirements and findings showing that the city's
adopted comprehensive plan and development regulations are "substantially similar" to the requirements of
RCW 36.70A.635 (see RCW 36.70A.636(3)). This approach requires Department of Commerce approval.
For more information about these alternatives, see Chapter 6.0.
Critical Areas
RCW 36.70A.635(8)(a) provides that if any portion of a lot has a designated critical area, or any portion of a lot
has a buffer associated with a designated critical area, then the requirements of RCW 36.70A.635 do not apply
to the entire lot. Critical areas are defined by the GMA as the following areas and ecosystems:
• Wetlands
• Areas with a critical recharging effect on aquifers used for potable water
• Fish and wildlife habitat conservation areas (this does not include such artificial features as irrigation
delivery systems, irrigation infrastructure, irrigation canals, or drainage ditches)
• Frequently flooded areas
• Geologically hazardous areas
As an alternative, cities are encouraged to apply critical area regulations to middle housing in the same
manner such regulations are applied to detached single-family residences. This is because RCW
36.70A.635(8)(a) could substantially reduce housing capacity by restricting development on lots where a
middle housing development could otherwise meet critical area code requirements. Treating middle housing
the same as detached single-family residences may also provide an opportunity to better implement the
27 In this option the minimum density standard will vary according to the minimum and actual lot sizes in a zone and the local
development patterns. For example, in a Tier 2 city zone with 5,000 square foot lots where four units per lot are allowed, a minimum
density standard at or above 35 units per acre would permit higher densities or intensities than required by RCW 36.70A.635.
In a Tier 1 city zone with 5,000 square foot lots where six units per lot are allowed, a minimum density standard at or above 53 units per
acre would permit higher densities or intensities than required by RCW 36.70A.635.
28 Mixed -use multifamily zones are not subject to RCW 36.70A.635 per the definition of "all lots zoned predominantly for residential
use." Cities are encouraged to provide multifamily zones which are mixed -use with a variety of allowed non-residential commercial
uses, including but not limited to retail, services, eating and drinking establishments, entertainment, recreation, and office uses. This
can help provide jobs, shopping, and services in close proximity to more homes and people and help cities achieve any policy objectives
related to climate change, environment, equity, affordable housing, transportation, and economic development.
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Housing Element requirements to make adequate provisions for existing and projected needs of all economic
segments of the community.
In other words, cities have the option to not adopt Model Ordinance Section 4, subsection (13)(1). Cities
choosing not to adopt subsection (13)(1) must still include lots designated with critical areas or their buffers in
the 25 percent of lots where unit per lot requirements are not implemented, if the "Alternative to Density
Requirements" (RCW 36.70A.635(4)) approach is used. For more information see User Guide Chapter 6.1.
Regardless of a jurisdiction's approach to middle housing and critical areas, jurisdictions should plan for
natural hazards and open space preservation. See Chapter 4.4 for more information.
Impaired or Threatened Watersheds
Per the RCW, the relevant watersheds are those serving a reservoir for potable (domestic) water. The
geographic eligibility for this exemption may be very limited. There is no statewide database on potable water
reservoirs, so cities need to consult local information to determine if this exemption applies in their
jurisdiction.
Watersheds are not categorized as impaired or threatened under section 303(d) of the Federal Clean Water
Act, but individual water body segments may be listed as impaired. Impaired water body segments are
identified as category 4 or 5 on the Water Quality Atlas maintained by the Department of Ecology (the
department does not use the term "threatened"). Therefore, cities can reasonably interpret the RCW to be
referring to watersheds which contain an impaired water body segment.
Cities should not adopt this provision if a watershed meeting the criteria identified in 36.70A.635(8)(c) does
not exist within the city limits. Note that new development allowed by middle housing regulations has the
potential to reduce impacts on watersheds by incorporating current stormwater best management practices
on -site and contributing to utility improvements.
For related information, cities can also review the Washington State Water Quality Assessment database and
filter for Category 4 and 5 water body segments. The most directly applicable use designation is "water supply
— domestic water." There are a limited number of impaired water body segments used for domestic water and
their watersheds are not applicable to the exemption if the watershed does not serve a potable water reservoir.
Other water use designations may be of interest to cities for planning purposes depending on the local context
Urban Separators
Some counties designate lands as "urban separators" under their countywide planning policies (CPP's). These
also serve as "open space corridors", described by RCW 36.70A.160. These are corridors of land on the
periphery of incorporated areas that provide visual breaks in the landscape and link open spaces between
municipalities and rural areas, and typically have very low permitted residential densities. The King County
CPP's use this concept.
Cities should not adopt this provision if an urban separator(s) meeting the criteria identified in RCW
36.70A.635(8)(c) does not exist within the city limits.
References
• Washington State Department of Commerce - Critical Areas Handbook
• Washington State Department of Ecology — Water Quality Assessment and 303(d) List (landing page)
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• Washington State Department of Ecology - Washington State Water Quality Assessment29 (searchable
database)
• Washington State Department of Ecology - Water Quality Atlas30 (interactive GIS map)
• Washington State Department of Ecology - Water Quality Program Policy 1-11 (more information on water
quality categories)
• United States Geological Survey - Watershed Boundary Dataset and Access National Hydrography a
Products o
• King County - Urban Separators under King County Countywide Planning Policies (GIS data)
29 Note that assessments are done every few years; as of this writing, anything listed with a date of 2018 and before is considered
applicable. Any water body segments listed as only 2022 (the next assessment to be approved) will be listed after the July 23, 2023,
date.
30 Filtering by "305(b) report — includes 303(d) list" will show all categories and the resulting map can be filtered to display only
categories 4 and 5. Click "add/remove map data" to add 8-, 10-, or 12-digit hydrologic unit codes (HUC); the larger the HUC, the smaller
the watershed scale. 16-digit HUC codes are not available on this map.
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2.5 - Unit Density and Affordable Housing
The Model Ordinances define "unit density" as the number of dwelling units allowed on a lot, regardless of lot
size. HB 1110 requires that applicable cities regulate density in applicable residential zones in a way that has
not commonly been done in the past. Section 5 of the Model Ordinances identifies specific unit per lot density
requirements for each city tier and includes affordable housing provisions that apply to Tier 1 and 2 cities.
Section 5 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
Tier 3 Cities
A. The permitted unit density on all lots zoned predominantly for residential use is two units per lot, unless
zoning permitting higher densities or intensities applies.31,32
B. The standard of subsection (A) does not apply to lots after subdivision below 1,000 square feet unless the
city has a smaller allowable lot size in the zone.33
Tier 1 Cities
A. The permitted unit density on all lots zoned predominantly for residential use is:31,35
1. Four units per lot, unless zoning permitting higher densities or intensities applies.
2. Six units per lot on all lots within one -quarter mile walking distance of a major transit stop, unless
zoning permitting higher densities or intensities applies.
3. Six units per lot if at least two units on the lot are affordable housing meeting the requirements of
subsections (C) through (H) below, unless zoning permitting higher densities or intensities applies.36
B. The standards of subsections (A) do not apply to lots after subdivision below 1,000 square feet unless the
city has enacted an allowable lot size below 1,000 square feet in the zone.37
31 RCW 36.70A.635(1)(c) uses the phrase "at least" when describing these densities, so cities should treat these as floors for maximum
unit density. Cities can allow higher densities.
32 Because middle housing can reach considerable densities (two units on a 5,000 square feet lot is approximately 18 units per acre)
cities should not assume existing multifamily zones necessarily permit "higher densities or intensities." See further information in User
Guide Chapter 2.4.
33 RCW 36.70A.635(6)(g)
34 RCW 36.70A.635(1)(b). RCW 36.70A.635(1) uses the phrase "at least" when describing these densities, so cities should treat these
as floors for maximum unit density. Cities can allow higher densities.
35 Because middle housing can reach high densities (four units on a 5,000 square feet lot is approximately 35 units per acre) cities
should not assume existing multifamily zones necessarily permit "higher densities or intensities." See further information in User Guide
Chapter 2.4.
36 The affordable housing increase is not required to be available within one -quarter mile walking distance of a major transit stop unless
a city chooses to do so. See the "combined housing unit increase" described under Local Policy Choice.
37 RCW 36.70A.635(6)(g)
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Tier 2 Cities
A. The permitted unit density on all lots zoned predominantly for residential use is:","
1. Two units per lot, unless zoning permitting higher densities or intensities applies.
2. Four units per lot on all lots within one -quarter mile walking distance of a major transit stop, unless
zoning permitting higher densities or intensities applies.
3. Four units per lot if at least one unit on the lot is affordable housing meeting the requirements of
subsections (C) through (H) below, unless zoning permitting higher densities or intensities applies."
B. The standards of subsections (A) do not apply to lots after subdivision below 1,000 square feet unless the
city has enacted an allowable lot size below 1,000 square feet in the zone. 41
Tier 1 and 2 Cities42
C. To qualify for additional units under the affordable housing provisions of Section 5(A), an applicant shall
commit to renting or selling the required number of units as affordable housing and meeting the standards
of subsections (D) through (H) below.43
D. Dwelling units that qualify as affordable housing shall have costs, including utilities other than telephone,
that do not exceed 30 percent of the monthly income of a household whose income does not exceed the
following percentages of median household income adjusted for household size, for the county where the
household is located, as reported by the United States Department of Housing and Urban Development:
44, 45, 46
1. Rental housing: 60 percent.
2. Owner -occupied housing: 80 percent.41
E. The units shall be maintained as affordable for a term of at least 50 years, and the property shall satisfy
that commitment and all required affordability and income eligibility conditions.
38 RCW 36.70A.635(1)(a). RCW 36.70A.635(1) uses the phrase "at least" when describing these densities, so cities should treat these as
floors for maximum unit density. Cities can allow higher densities.
39 Because middle housing can reach high densities (four units on a 5,000 square feet lot is approximately 35 units per acre) cities
should not assume existing multifamily zones necessarily permit "higher densities or intensities." See further information in User Guide
Chapter 2.4.
40 The affordable housing increase is not required to be available within one -quarter mile walking distance of a major transit stop unless
a city chooses to do so. See the "combined housing unit increase" described under Local Policy Choice.
41 RCW 36.70A.635(6)(g)
42 The affordable housing provisions are not required to be adopted by Tier 3 cities.
43 RCW 36.70A.635(2)
44 Maximum monthly housing costs, with a housing cost burden of 30%, should be defined to be consistent with household gross
income and adjusted income calculations for eligibility of affordable housing programs by HUD.
45 "Income Limits." United States Census. https://www.huduser.gov/portal/datasets/il.html
46 RCW 36.70A.030
47 See User Guide Chapter 5.0 for information on administering affordable homeownership programs.
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The applicant shall record a covenant or deed restriction that ensures the continuing rental or ownership of
units subject to these affordability requirements consistent with the conditions in chapter 84.14 RCW for a
period of no less than 50 years.48
G. The covenant or deed restriction shall address criteria and policies to maintain public benefit if the property
is converted to a use other than that which continues to provide for permanently affordable housing.
H. The units dedicated as affordable housing shall:
1. Be provided in a range of sizes comparable to other units in the development.
2. The number of bedrooms in affordable units shall be in the same proportion as the number of bedrooms
in units within the entire development.
3. Generally, be distributed throughout the development and have substantially the same functionality as
the other units in the development.
Local Policy Choice
One -Half Mile Walking Distance to Major Transit Stops
In Model Ordinance Section 6, subsection (B), Tier 1 and 2 cities are encouraged to replace "one -quarter mile"
with "one-half mile" for where the higher density requirement in proximity to transit applies. This
recommendation aligns with the required one-half mile walking distance standard for the elimination of off-
street parking requirements in Model Ordinance Section 7 and increases housing capacity. See Chapter 3.2 for
guidance on how walking distance is measured.
Cities should also consider going beyond these requirements near major transit stops and permitting transit -
oriented densities, multifamily housing, and a variety of non-residential uses.
Combined Housing Unit Increase
Unless zoning permits higher lot densities or intensities, Tier 1 cities must allow at least six units and Tier 2
cities must allow at least four units on lots zoned predominantly for residential use within one -quarter mile
walking distance of major transit stops. Tier 1 cities must separately allow at least six units, and Tier 2 cities at
least four units per lot, when affordable housing units meeting the provisions of RCW 36.70A.635(2) are
provided in any location outside of a one -quarter mile walking distance of major transit stops.
Tier 1 and 2 cities may also consider combining the allowed unit density increases to increase housing
capacity and affordable housing near major transit stops. This has the benefit of improving access to transit to
lower -income households. The effect of using this option is:
• In a Tier 1 city, a lot located within one -quarter mile (or half -mile, as encouraged above) walking distance of
a major transit stop and which has at least two affordable units would be permitted a minimum of eight
units on the lot.
48 Refer to for the Department of Commerce website for guidance on covenant and deed restrictions related to chapter 84.14 RCW (see
"21-23 Work Products and Updates"). https://www.commerce.wa.gov/serving-communities/growth-management/growth-
management-topics/planning-for-housing/multi-family-housing-property-tax-exemption-program/
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In a Tier 2 city, a lot located within one -quarter mile (or half -mile, as encouraged above) walking distance of
a major transit stop and which has at least one affordable unit would be permitted a minimum of six units
on the lot. P
Cities are encouraged to consider going beyond the requirements of RCW 36.70A.635 near major transit stops
and permitting transit -oriented densities, multifamily housing, and a variety of non-residential uses.
Alternative Affordability Requirements or Incentives
RCW 36.70A.635(2)(c) and (3) allow cities to adopt alternate affordability program terms for middle housing
development. However, adoption of alternate program terms does not mean that the affordability bonus of
RCW 36.70A.635(1) may be altered or replaced. See the discussion of affordable housing in Chapter 5.0.
Zoning Permitting Higher Densities or Intensities
The affordable housing requirement for Tier 1 and 2 cities includes the statement, "...unless zoning permitting
higher densities or intensities applies..." 49 This means that if a Tier 1 city's zoning permits a greater number of
units than the minimum four units per lot required by RCW 36.70A.635(1)(b)(i), and a Tier 2 city's zoning
permits a greater number of units than the minimum two units per lot required by RCW 36.70A.635(1)(a)(i),
then a city may choose not to apply the affordable housing requirement.
In other words, a Tier 1 or Tier 2 city subject to RCW 36.70A.635 does not have to require affordable housing
units on lots predominantly zoned for residential use in a zone, but only when:
A Tier 1 city permits a base unit density of at least five units per lot in the zone.
A Tier 2 city permits a base unit density of at least three units per lot in the zone:
However, to plan for and accommodate housing for all income levels, cities choosing this option should
consider of other ways to increase the supply of affordable housing. Cities with higher density/intensity limits
for a zone may still require affordable units in middle housing developments under RCW 36.70A.540. Providing
an affordable housing incentive to achieve higher densities could also assist cities in meeting new Growth
Management Act (GMA) Housing Element requirements. This includes identification of the number of housing
units necessary to plan for projected growth by income band (RCW 36.70A.070(2)). See the discussion of
affordable housing in Chapter 5.0 of this User Guide.
Cottage Housing Density Bonus
A unit density bonus is often needed for cottage housing to be financially viable because cottages are required
to be smaller than the regular detached single-family residences being built by the market. Cities should review
their existing cottage housing regulations, and if applicable apply a cottage housing density bonus. A two -for -
one bonus is common in Washington cities, with some cities going lower or higher. See also the design
standards for cottage housing in Section 8 of the Model Ordinance.
49 Because middle housing can reach high densities (four units on a 5,000 square feet lot is approximately 35 units per acre) cities
should not assume existing multifamily zones necessarily permit "higher densities or intensities." See more information in User Guide
Chapter 2.4.
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Discussion
Code Format
As different cities' development regulations take on different formats to identify allowed uses and number of
units (i.e., itemized list, tables), the specific code amendment format will vary. Existing maximum density limits
which conflict with the provisions of RCW 36.70A.635 are invalidated in the model ordinance.
Accessible Housing
Since 1991 the Fair Housing Act (FHA) has required that certain dwellings be readily accessible and usable by
people with disabilities. In buildings with four or more units and without elevators the ground floor dwelling
units must be accessible. Townhouse units are generally exempted unless they are part of larger building with
an elevator.so
Stairs are an impediment to people with some physical disabilities and can prevent full use of a home or create
a personal injury hazard.51 This often includes seniors, who are an increasing share of the population.
Cities should consider the opportunity to increase the supply of accessible housing by allowing buildings with
at least four units and single -level ground -floor units in more locations. For example, when choosing the six of
nine types required (see User Guide Chapter 2.6), fourplexes and courtyard apartments may provide more
opportunities for accessible housing than stacked flats and townhouses. However, the provision of accessible
housing should not be viewed competitively. A general benefit of permitting a variety of middle housing and
meeting the requirements of RCW 36.70A.635 is providing more choice of housing for people at all stages of
life and at different points on the spectrum of physical mobility.
Providing additional zoned capacity for multi -story, elevator -served multifamily housing is another way for
cities to encourage accessible housing options.
Compatibility and Scale of Middle Housing
The statute language focuses on two to six dwelling unit
middle housing types that are defined as being compatible
with the form, scale, and character of single-family dwellings
However, middle housing is often considered in the planning
and development industries to also include small
apartments, multiplexes, and courtyard apartments with up
to 20 dwelling units. Cities implementing HB 1110 will begin
to move away from single -family -home -only neighborhoods
to single-family homes being one of many housing types in
residential neighborhoods.
FM
Single-family home and duplex. Source. MAKERS
Research from the University of California Berkeley's Terner Center for Housing Innovation suggests middle
housing projects with eight to twelve dwelling units is the ideal project size to best achieve economies of scale
in housing production. As cities prepare to amend development regulations to comply with RCW 36.70A.635,
they may consider allowing denser middle housing developments, especially in areas near transit, commercial
50 "Multistory Townhouses and Accessibility: When does the FHA apply?" MAP Strategies. https://ma-
strategies.com/ideas/multistory-townhouses-and-accessibility-when-does-the-fha-apply
51 "Our Bans on Stacked Homes Are Bans on Age -Ready Homes." Sightline. https://www.siahtline.org/2019/05/15/our-bans-on-
stacked-homes-are-bans-on-age-ready-homes/
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services and job centers, and other amenities. Cities interested in denser middle housing projects should also
review Senate Bill 5491 regarding single -stair multifamily structures.
References
• Department of Commerce - Middle housing building types
• Department of Commerce - Racially Disparate Impacts Guidance (pages 37 & 50 - 53)
• United States Census - Income Limits
• University of California Berkely Terner Center - Housing Innovation Brief. 2022 (page 9)
• Local, regional, and national trends showing the decline in two -to -nine -unit projects over the last 20 years
(Urban Institute. 2023, pg. 51; Eye on Housing, 2017 & 2021).
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2.6 — Middle Housing Types
Section 6 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
Subject to the requirements of RCW 36.70A.635(5), on all lots zoned predominantly for residential use the
following uses are permitted by -right, unless zoning permitting higher densities or intensities than those listed in
Section 5 of this ordinance applies:52
A. Duplexes.
B. Triplexes.
C. Fourplexes.
D. Fiveplexes.
E. Sixplexes.
F. Townhouses.
G. Stacked flats.
H. Courtyard apartments.
I. Cottage housing.
Local Policy Choice
For jurisdictions that do not meet the statutory deadline for compliance with RCW 36.70A.635, all nine types of
middle housing are permitted by -right in the Model Ordinance on all lots zoned predominantly for residential
use until such time the city takes all actions necessary to implement RCW 36.70A.635. The purpose of this in
the Model Ordinance is not to pre -judge which six middle housing types should be allowed if the Model
Ordinance goes into effect for a jurisdiction that has not met its statutory deadline for adopting middle housing
regulations.
For cities adopting middle housing regulations, whether prior to or after the statutory deadline, consider the
following:
52 RCW 36.70A.635(5)
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Tier 1 Cities
In each zone where lots are zoned predominantly for residential use, amend allowed use standards to permit at
least six of the nine middle housing types within the definition of "Middle Housing" per RCW 36.70A.635(5).
While six is the minimum, jurisdictions may include more to provide more flexibility for the development of
middle housing types.
Tier 2 Cities
In each zone where lots are zoned predominantly for residential use, amend allowed use standards to permit at
least six of the nine middle housing types within the definition of "Middle Housing" per RCW 36.70A.635(5).
Where only two units per lot are allowed, cities may apply a supplemental standard, footnote, or other notation
stating that middle housing building types which contain more than two dwelling units (e.g., triplexes,
townhouses, or fourplexes) are allowed only where transit or affordable housing bonuses apply.
Tier 3 Cities
Tier 3 cities must allow two units per lot (RCW 36.70A.635(1)(c)). In each zone where lots are zoned
predominantly for residential use, Tier 3 cities should amend allowed use standards to permit at least the four
of the nine middle housing types within the definition of "Middle Housing" that allow for two units per lot.
These are duplexes, stacked flats, cottage housing, and courtyard apartments.
This guidance follows that portion of RCW 36.70A.635(5) which states cities are only required to allow as
many middle housing types as needed to meet the unit density requirement. However, this guidance
recommends that cities consult with their city attorney on this approach given the requirement, also in RCW
36.70A.635(5), that cities allow at least six of nine middle housing to achieve the unit density requirements.
Tier 3 cities are encouraged to provide a variety of housing choices and may consider allowing more than two
units per lot to achieve the six building type minimum, such as triplexes and fourplexes.
Housing Uses Allowed By -Right
RCW 36.70A.600(1) encourages cities to update use matrices and allowable use tables that eliminate
conditional use permits and administrative conditional use permits for all housing types, including single-
family homes, townhouses, multifamily housing, low-income housing, and senior housing, but excluding
essential public facilities.
Zoning Permitting Higher Densities or Intensities
Similar to the option cities have to allow higher unit density requirements, as noted under Section 5 of the
Model Ordinance, the requirement to allow at least six types of middle housing also does not apply to where
zoning permitting higher densities or intensities applies.
RCW 36.70A.635(5) states in part, "...[a] city must allow at least six of the nine types of middle housing to
achieve the unit density required in subsection (1) of this section", and in RCW 36.70A.635(1), the unit density
standards do not apply where "zoning permitting higher densities or intensities applies." Therefore, the six -of -
nine types requirement does not apply in zones where higher densities or intensities applies. Because middle
housing can reach high densities (four units on a 5,000 square feet lot is approximately 35 units per acre)
cities should not assume existing multifamily zones necessarily permit "higher densities or intensities".
Multiple Detached Single -Family Residences on a Lot
Cities have the option to allow multiple detached single-family residences on a lot to take advantage of unit
density requirements. For example, a lot with a unit density of four could either have a fourplex building, two
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duplex buildings, four cottage housing buildings, or four detached single-family residences, if zoning allows
multiple detached single family dwellings on a lot. Therefore, cities desiring the flexibility of this option would
need to clarify that multiple detached single-family residences are a permitted use. This option is similar to
cottages in that the units are detached, but they wouldn't come with special size restrictions and design
requirements. Special considerations for this option: s
• Allowing multiple detached single-family residences per lot significantly increases the flexibility of
residential zoning and increases the options available to preserve existing one -unit houses when adding
new housing to a lot.53
• Detached housing is typically more expensive and requires more land area than middle housing.
• Design elements such as vehicular access, parking, garages, minimum building separation, minimum
usable open space, among other site layout issues.
• Multiple detached single-family residences on a lot does not require a subdivision. Such units can be
condominiums or owned in common and rented.
Discussion
Number of Middle Housing Types
To address housing need by promoting a variety of residential densities and housing types, jurisdictions are
encouraged to permit more than six middle housing types. Note that accessory dwelling units are not one of
the nine types of middle housing building types per the definition of middle housing, (RCW 36.70A.030(26)) but
may be counted towards achieving the unit density in RCW 36.70A.635(1).
_9ft hM_
Examples of the nine middle housing types. Source: MAKERS
53 "Backyard Homes Are Great For Owners of Small Homes." Sightline Institute, 2022. https://www.sightline.org/2022/01/05/backyard-
homes-are-great-for-owners-of-smal I -homes/
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Location Restrictions
Cities should review their codes for supplemental use standards related to spacing, distribution, buffering, and
similar location restrictions for middle housing. Such standards are not permitted if they create a greater
restriction on the permitted location of middle housing compared to detached single-family residences in the
same zone. For example, a requirement for duplexes to not be on adjacent lots or a requirement for duplexes
to be separated by 500 feet is not allowed where no such standards exist for detached single-family
residences in the same zone.
Code Format
As different cities' development regulations take on different formats to identify allowed uses (i.e., itemized
list, use tables), the specific code amendment format will vary.
References
• Middle housing images (Commerce; Sightline Institute)
• Department of Commerce - Middle housing informational posters
• Department of Commerce - Middle housing building types and block models
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2.7 - Dimensional Standards
The model ordinances include both minimum HB 1110 requirements and recommend standards to make
middle housing compatible with the scale, form and character of detached single family dwellings.
Notable provisions integrated into the model codes:
HB 1110 requires that dimensional standards for middle housing be no more restrictive than those
standards applying to detached single-family residences.
The model ordinances invalidate existing dimensional standards that are seen as incompatible with middle
housing. Examples include specific thresholds for units per structure, maximum building height, minimum
setbacks, maximum lot coverage, and maximum floor area ratio.
Lastly, the model ordinance dimensional standards for Tier 1 and 2 Cities intentionally differs from Tier 3
standards. These differences reflect the potential for a greater number of units per lot for Tier 1 and 2 Cities
versus Tier 3 Cities, and the differing levels of staffing and code complexity that might differ between Tier 1
and 2 Cities versus Tier 3 Cities.
Section 7 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
Tier 1, 2, and 3 Cities
A. Applicability.
1. The city shall not require through development regulations any standards for middle housing that are
more restrictive than those required for detached single-family residences, but may apply any objective
development regulations that are required for detached single-family residences. This includes, but is
not limited to, the following types of dimensional standards: building height, setbacks, lot coverage,
floor area ratio, lot area and lot dimension, impervious surface, open space, and landscaped area
standards. sa
2. Dimensional standards invalidated by this section are replaced by the dimensional standards provided in
this section.
B. Density. Lot area requirements and unit density shall comply with Section 5 of this ordinance. Other
restrictions, such as minimum lot area per unit, or maximum number of housing units per acre, are invalid in
relationship to the minimum number of units per lot that the City must allow under RCW 36.70A. 635. 55,56
C. Units per structure. Minimum and maximum numbers of dwelling units per structure for middle housing are
invalid, except as provided by the definitions of middle housing types in Section 2 of this ordinance.
54 RCW 36.70A.635(6)(b) refers to setbacks and lot coverage as examples of development regulation dimensional standards. For clarity
on this provision, additional examples of dimensional standards are added in the Model Ordinance.
55 For more discussion on density measurements, see User Guide Chapter 4.3.
56 Cities may set higher units per lot or minimum units per acre standards than prescribed in RCW 36.70A.635(1) where multifamily is
the predominant residential use intended for a zone. See more information in User Guide Chapter 2.4.
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D. Maximum building height: 35 feet. A maximum building height limit for middle housing of less than 35 feet is
invalid.57
1. Building height shall be measured in accordance with the city's development regulations.
2. Rooftop appurtenances shall be regulated and measured in accordance with the city's development
regulations.
Tier 1 and 2 Cities
E. Minimum setbacks.
1. The minimum required setbacks are as follows. Minimum setbacks from property lines for middle
housing buildings greater than the following are invalid:
a. Street or front: 15 feet, except 10 feet for lots with a unit density of three or more.
b. Street or front, garage door (where accessed from a street): 20 feet.
c. Side street: Five feet. ss
d. Side interior: Five feet, and zero feet for attached units internal to the development.
e. Rear, without an alley: 15 feet, except 10 feet for lots with a unit density of three or more.
f. Rear alley: Zero feet, and three feet for a garage door where it is accessed from the alley.
2. Setback projections.
a. Covered porches and entries may project up to five feet into required front and rear setbacks
b. Balconies and bay windows may project up to three feet into required front and rear setbacks.
c. Required parking spaces may occupy required setbacks.
d. Other setback projections shall be regulated and measured in accordance with the city's development
regulations.
F. Maximum lot coverage.
1. The maximum lot coverage for middle housing areas follows. Maximum lot coverage less than the
following is invalid:
a. For lots with a unit density of six: 55 percent.
b. For lots with a unit density of four or five: 50 percent.
c. For lots with a unit density of three or less: 45 percent.
57 See the Local Policy Choice section for an option cities may consider to incentivize pitched roofs.
58 The side street setback applies to corner lots. The "side street" is the street other than the street from which the lot fronts upon.
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2. Unless the city has a different pre-existing approach to measuring lot coverage, lot coverage is measured
as follows: the total area of a lot covered by buildings or structures divided by the total amount of site
area minus any required or planned dedication of public rights -of -way and/or designation of private
rights -of -way, and does not include building overhangs such as roof eaves, bay windows, or balconies
and does not include paved surfaces.
G. Maximum floor area ratio (FAR).
1. Maximum FAR for middle housing is as follows. Maximum floor area ratio less than the following is
invalid:
2. Unless the city has a different pre-existing approach to measuring FAR, FAR is measured as follows: the
total interior floor area of buildings or structures on a site, excluding features listed in subsection (G)(3)
below, divided by the total amount of site area minus any required or planned dedication of public rights -
of -way and/or designation of private rights -of -way. For example, a maximum floor area ratio of 1.0 (1 to
1) means one square feet of floor area is allowed for every one square foot of site area.
3. Unless FAR is measured differently by the city's development regulations, the following are not included
in the calculation of interior floor area:
a. Cottage housing developments meeting the standards of Section 8 of this ordinance.
b. Unoccupied accessory structures, up to a maximum equal to 250 square feet per middle housing unit
c. Basements, as defined by the city's development regulations.
d. Unenclosed spaces such as carports, porches, balconies, and rooftop decks.
59 0.6 FAR applies to a detached single-family residence. See further information in the Local Policy Choice section below.
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Tier 3 Cities
E. Minimum setbacks.
The minimum required setbacks are as follows. Minimum building setbacks from property lines for
middle housing buildings greater than the following are invalid:
a. Street or front: 15 feet, except 10 feet for lots with a unit density of three or more.
b. Street or front, garage door (where accessed from a street): 20 feet.
c. Side street: Five feet.60
d. Side interior: Five feet, and zero feet for attached units internal to the development.
e. Rear, without an alley: 20 feet.
f. Rear alley: Zero feet, and three feet for a garage door where it is accessed from the alley.
2. Setback projections.
a. Covered porches and entries may project up to five feet into required front and rear setbacks
b. Balconies and bay windows may project up to three feet into required front and rear setbacks.
c. Required parking spaces may occupy required setbacks.
d. Other setback projections shall be regulated and measured in accordance with the city's development
regulations.
F. Maximum lot coverage.
The maximum lot coverage for middle housing is 40 percent. A maximum lot coverage limit for middle
housing of less than 40 percent is invalid.
2. Unless the city has a different pre-existing approach to measuring lot coverage, lot coverage is measured
as follows: the total area of a lot covered by buildings or structures divided by the total amount of site
area minus any required or planned dedication of public rights -of -way and/or designation of private
rights -of -way. Lot coverage does not include building overhangs such as roof eaves, bay windows, or
balconies and it does not include paved surfaces.
60 The side street setback applies to corner lots. The "side street" is the street other than the street from which the lot fronts upon
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Local Policy Choice
Maximum Building Height
The model code uses a 35 feet maximum building height to accommodate three stories. This is consistent
with the definition used for stacked flats (RCW 36.70A.030(40)), which defines a stacked flat as being no more
than three stories. If pitched roof forms are desired, some adjustments may be needed depending on how
height is measured. For those cities where the height is measured to the top of the roofline rather than the mid-
point, consider this language:
#. The maximum height limit for middle housing is 40 feet where all roof forms above 35 feet have a
minimum 3:12 roof pitch.
Setbacks
Cities may choose to adopt setbacks with consistent standards regardless of the middle housing type or unit
density, or to offer flexibility to help incentivize middle housing development. In the Tier 1 and 2 Cities Model
Ordinance, reduced setbacks for three or more units are intended to incentivize middle housing. Cities that
want to simplify the code could adjust the front and rear setback standards under subsection (E) to be a
consistent number regardless of unit density on the lot. Lower setbacks (e.g., 10 feet for Tier 1 and 2 cities) are
recommended to provide flexibility for middle housing development.
Cities might also consider a different set of setback standards that apply to new dwelling units placed within or
towards the rear of the lot, provided they preserve some usable open space on the lot. This could be similar to
many cities' approaches for detached accessory dwelling units (ADU's), where rear setbacks for primary
structures might be 20 feet, but a detached ADU could be within five or 10 feet of a rear property line provided
it meets other dimensional and design standards. Other types of incentives may be considered. For example, in
some residential zones the city of Bothell allows a reduced front setback only if the rear setback is increased
by the same amount to help preserve trees, provide space for rain gardens, etc.
Note that even with zero -foot setbacks there may be other limitations to how close structures can be property
lines. Cities may prohibit foundation footings and roof eaves from extending beyond a property line onto right-
of-way or adjacent property, though some cities permit this with easements. Building codes and fire codes
may also restrict how close separate structures can be to each other, depending on the fire-resistant qualities
of each structure's design.
Lot Coverage and Floor Area Ratio
The Model Ordinance for Tier 1 and 2 Cities employs both lot coverage and floor area ratio (FAR) to balance
the advantages of each standard. The Model Ordinance for Tier 3 Cities, which accommodates fewer units per
lot, only employs lot coverage.
Cities opting to craft their own middle housing dimensional standards will need to review their current zoning
tools and thresholds Lot coverage is commonly used to manage building footprint and promote and open
space. FAR is an increasingly common tool used to control building size.
The table below identifies the basic advantages and disadvantages to using lot coverage and FAR.
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. Relatively easy to understand and calculate Less effective than FAR in managing the
Lot coverage • Can help ensure that there's some amount building massing on a lot because buildings
of open space on the lot can go up to the maximum height limit for
the full allowed lot coverage
. More effective than lot coverage in Fewer cities currently regulate FAR, thus it's
managing building massing on a lot
Floor area ratio because it sets maximum floor area limits an additional layer of review and can be
proportional to the lot size perceived as more complicated to calculate
Lot Coverage
Lot coverage limits the area of building footprint compared to site area, usually expressed as a maximum
percentage. For example, a lot coverage of 40% means 40% of a lot's total area is covered by a building. To be
meaningful the maximum permitted lot coverage needs to allow a smaller building footprint than relying on
setbacks alone. The Model Ordinances establish lot coverage thresholds that are approximately 5-20 percent
lower than would be allowed by setbacks alone. This balances an assurance for more open space on a lot
while still allowing a large enough building footprint area to accommodate middle housing.
The graphics below illustrate what 45 and 50 percent lot coverage look like on 40-foot by 100-foot lots.
Hypothetical minimum setbacks (in green) are 10 feet, 5 feet, and 10 feet for the front, side, and rear,
respectively. The unshaded areas of the lot (in white) show additional areas unrestricted by setbacks, but that
exceed lot coverage limits.
50% Lot Coverage
45% Lot Coverage
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Floor Area Ratio
Floor area ratio (FAR) compares the total floor area of the building to the site area (floor area = lot size = FAR),
with the result represented as a decimal number (0.5 or 1.0, for instance). For example, a 4,000 square feet lot
has its area multiplied by 1.0 FAR to arrive at a maximum floor area of 4,000 square feet allowed to be
developed. The graphic below illustrates this example of two-story and three-story configurations
FAR 1.0
C;
The top diagrams illustrate what an FAR of 1.0 looks like in a variety of configurations. The bottom two diagrams show what 1.0 FAR may
look like specifically on a 4,000 square foot lot in two- and three-story configurations.
FAR is a popular tool for cities to manage building massing where middle housing is allowed because it limits
building size without directly limiting unit count. However, many cities also do not use FAR.
The FAR standards for Tier 1 and 2 Cities in Model Ordinance Section 7, subsection (G), are written to consider
a typical lot size of 5,000 square feet and accommodating "family -sized" units with two to four bedrooms,
which are the most common housing unit sizes in Washington.11,62 An analysis used an average middle
housing unit size of 1,400 square feet.63 This size is roughly in the middle of Washington state's average
61 The FAR limits were tested on other lot sizes ranging from 4,000 square feet to 7,500 square feet. On smaller lots these limits could
still allow two -bedroom units. On larger lots FAR standards become less of a limitation on average unit size because average unit size
becomes larger than is what is likely to be built for middle housing under normal market conditions.
62 United States Census, Table DP04 ACS 2022 1-Year Estimates
63 Other average unit sizes were tested, ranging from 1,000 to 1,600 square feet. It was reasonable to test sizes larger than 1,000
square feet, which is the maximum gross floor area for accessory dwelling units that must be allowed under RCW 36.70A.681, and less
than 1,600 square feet, which is the maximum size of individual cottage housing units established in Model Ordinance 3.OSection 8.
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single-family homes (2,185 square feet64) and multifamily apartments (824 square feet 15). Resulting FAR
numbers were rounded up or down resulting in potentially different unit size averages.
Flexibility provided by the FAR standards in the Model Ordinance allow for middle housing to respond to the
needs of not only families and larger households, but also smaller households if a builder chooses to build
smaller units. One -person households make up approximately 28 percent of Washington households.66 In high-
priced urban markets one -person households tend to be renters and high-income.67
Note that the floor area ratio standard also applies to detached single-family residences. RCW
36.70A.635(6)(b) requires, in part, that cities "...shall not require through development regulations any
standards for middle housing that are more restrictive than those required for detached single-family
residences, but may apply any objective development regulations that are required for detached single-family
residences..." In other words, if a type of dimensional standard is not applied to detached single-family
residences, it cannot be applied to middle housing. However, equal or less restrictive standards can be applied
to middle housing as compared to single-family.
Approach Options
Cities have choices in how they employ lot coverage and FAR, including the following explored as part of
developing the Model Ordinance.
Consistent standards. In this approach, a single standard is applied uniformly to all lots in a zone.
Progressive standards. In this approach, cities apply standards that incentivize middle housing by allowing
more flexibility in exchange for a higher number of units on a lot. The Model Ordinance for Tier 1 and 2
cities applies a progressive approach for both lot coverage and FAR, with higher coverage and more floor
area allowed for additional units. This approach was selected after testing development scenarios on lot
sizes from 3,000 to 5,000 square feet, assuming that standards that work for these small lots are workable
for the full range of lot sizes.
Lot -sized based standards. In this approach, cities apply standards that change based on the lot size,
using the assumption that lot size can help or hurt the ability to comply with the standards. For example,
Oregon Middle Housing Code for Large cities uses five different FAR tiers.
64 "The 2022 American Home Size Index." American Home Shield. https://www.ahs.com/home-matters/real-estate/the-2022-american-
home-size-index/
65 "Apartment Market Report Q3 2023." Washington Center of Real Estate Research, Runstad Department of Real Estate.
https://app.leg.wa.gov/committeeschedules/Home/Document/262886
66 United States Census, Table B11001 ACS 2022 1-Year Estimates
67 "Seattle's high housing costs haven't stopped people from living alone." The Seattle Times. 2024.
https://www.seattletimes. com/seattIe-news/data/seattles-high-housing-costs-havent-stopped-people-from-living-alone/
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Preserving Existing Homes
In some cases, it may be desirable for a middle housing
development to incorporate or preserve an existing
residential structure on the lot. It is especially advantageous
on lots with larger backyards where density allowances can
be met while retaining the existing home. Preserving the
existing home can allow a developer to recuperate a portion
of the investment costs more rapidly or allow a homeowner
to retain their home while allowing development on the rest
of the lot.
Providing incentives and methods to preserve existing
homes also provides cities an avenue to demonstrate
implementation of new GMA Housing Element requirements
focused on displacement. This includes new requirements
Example of a townhouse building built in the rear of an
existing single-family lot, accompanied by a unit lot
subdivision and a pedestrian access easement to the
street.
to identify areas at higher risk of displacement and local policies and regulations that result in displacement.
Options to incentivize preserving existing homes should be customized given every city is different. Some
basic provisions to incentive the preservation of existing homes while adding middle housing elsewhere on the
lot include:
• Exempt some or all of the existing home from FAR, lot coverage, and/or impervious standards.
Create a bonus density program where the existing home does not count towards to the overall density
limit on the lot.
Discussion
Economic Considerations
Cities should develop middle housing dimensional standards that makes the desired housing types and
housing outcomes the easier choice. For example, if attainable homeownership is a priority for a city, the city
should develop progressive dimensional standards that incentivize the production of that housing type over
larger, less dense, and more expensive housing types. Dimensional standards should consider the cumulative
effect on achieving the desired development types and should leave room for a reasonable unit size to be
feasible and create efficient floorplates for the desired development types.
Smaller Lot Sizes
Consideration for smaller lot sizes are listed below.
The dimensional standards in Section 7 were tested with 4,000-7,5000 square foot lots, a typical range in
cities subject to RCW 36.70A.635.
The provisions of RCW 36.70A.635 apply to all lots in residential zones greater than 1,000 square feet.
Some cities authorize lots as small as 2,500 square feet for detached single-family homes and 1,000
square feet or less specifically for townhouse development (where each townhouse unit sits on its own lot
and is attached to other townhouse units). For example, if a Tier 3 City has a 1,200 square foot minimum
lot size for townhouses, two townhouses could be integrated within a single 1,200 square foot lot, provided
they met applicable dimensional and design standards.
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Reducing minimum lot sizes is one of the most effective ways to support homeownership and increase
housing capacity.68 Cities interested in permitting very small lots should adjust dimensional standards to
ensure such lots are buildable. This may include reducing or removing side setback and lot coverage ;
requirements.
Because HB 1110's unit density requirements apply per lot, allowing smaller lots increases the total
number of units allowed significantly. For example, if a city decides to reduce the minimum lot size from
5,000 square feet to 2,500 square feet for a particular zone, such change would double the allowed density.
Cities should consider the long-term implications of allowing smaller lots, particularly in areas where there
are greenfield development opportunities for large new subdivisions given the middle housing provisions of
HB 1110. Naturally, the smaller the new lot is, the harder it will be to be to build middle housing and meet
all dimensional and design standards applicable to the zone.
References
• Portland Middle Housing Case Study (Cascadia Partners. 2023, pg. 11).
• Portland's development standards for R2.5 & R5 zones that produced the most middle housing
• Oregon Middle Housing Model Code Large Cities
• Spokane's Building Opportunity for Housing Code Amendments (2023, pgs. 104 — 108)
• Edmonton, Canada Zoning Bylaw Changes (2023, pgs. 15 — 30)
• Bozeman, Montana Draft Development Code Update (2023, pqs. 16 — 19)
68 "Lot -Size Reform Unlocks Affordable Homeownership in Houston." Pew Charitable Trusts. https://www.pewtrusts.org/en/research-
and-analysis/issue-briefs/2023/09/lot-size-reform-unlocks-affordable-homeownershi p-in-houston
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2.8 — Design Standards
RCW 36.70A.030 defines "middle housing" as "...buildings that are compatible in scale, form, and character
with single-family houses...". While design standards are not required, RCW 36.70A.635(6)(a) provides an
opportunity to use administrative design review and apply objective design standards for middle housing to
address compatibility with single-family houses, even if there are no design standards for single-family houses
in place.
Model Ordinance design standards include:
• Cottage housing and courtyard housing design standards to reflect objectives associated with the RCW-
defined housing types
• Basic pedestrian access provisions and design standards for vehicle access, carports, garages, and
driveways that balance practical needs to accommodate middle housing while prohibiting design forms
that have the potential to significantly impact the character of residential neighborhoods.
• Additional design standards related to entries, windows, and doors in the Model Ordinance for Tier 3 Cities.
Certain design standards above have been included for the purpose of ensuring that a city that needs to rely on
the Model Ordinance in the event it does not meet its HB 1110 compliance deadline to adopt middle housing
regulations has some basic design standards for middle housing types it may not currently permit in their city.
Section 8 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
Tier 1, 2, and 3 Cities
A. Applicability
1. These standards apply to all middle housing types, except for the specific cottage housing and courtyard
apartment standards which apply to only those types.
2. For the purposes of this section, a "street" refers to any public or private street and does not include
alleys.
3. These design standards do not apply to the conversion of a structure to a middle housing type with up to
four attached units, if the floor area of the structure does not increase more than 50 percent.
B. Purpose. The purpose of these standards is to:
1. Promote compatibility of middle housing with other residential uses, including single-family houses
2. De-emphasize garages and driveways as major visual elements along the street.
3. Provide clear and accessible pedestrian routes between buildings and streets.
4. Implement the definitions of cottage housing and courtyard apartments provided by state law.
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C. Design review. The process used for reviewing compliance with middle housing design standards shall be
administrative design review.
D. Cottage housing
Cottage size. Cottages shall each have no more than 1,600 square feet of net floor area, excluding
attached garages.
2. Open space. Open space shall be provided equal to a minimum 20 percent of the lot size. This may
include common open space, private open space, setbacks, critical areas, and other open space.
3. Common open space.
a. At least one outdoor common open space is required.
b. Common open space shall be provided equal to a minimum of 300 square feet per cottage. Each
common open space shall have a minimum dimension of 15 feet on any side.
c. Orientation. Common open space shall be bordered by cottages on at least two sides. At least half of
cottage units in the development shall abut a common open space and have the primary entrance
facing the common open space.
d. Parking areas and vehicular areas shall not qualify as common open space.
e. Critical areas and their buffers, including steep slopes, shall not quality as common open space.
4. Entries. All cottages shall feature a roofed porch at least 60 square feet in size with a minimum
dimension of five feet on any side facing the street and/or common open space.
5. Community building.
a. A cottage housing development shall contain no more than one community building.
b. A community building shall have no more than Z400 square feet of net floor area, excluding attached
garages.
c. A community building shall have no minimum off-street parking requirement.
E. Courtyard apartments.
1. Common open space.
a. At least one outdoor common open space is required.
b. Common open space shall be bordered by dwelling units on two or three sides.
c. Common open space shall be a minimum dimension of 15 feet on any side.
d. Parking areas and vehicular areas do not qualify as a common open space.
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2. Entries. Ground -related courtyard apartments shall feature a covered pedestrian entry, such as a covered
porch or recessed entry, with minimum weather protection of three feet by three feet, facing the street or
common open space.
F. Pedestrian access. A paved pedestrian connection at least three feet wide is required between each middle
housing building and the sidewalk (or the street if there is no sidewalk). Driveways may be used to meet this
requirement.
G. Vehicle access, carports, garages, and driveways.
1. For lots abutting an improved alley that meets the city's standard for width, vehicular access shall be
taken from the alley. Lots without access to an improved alley and taking vehicular access from a street
shall meet the other standards of subsection (G)(2) through (5) below.
2. Garages, driveways, and off-street parking areas shall not be located between a building and a street,
except when either of the following conditions are met:
a. The combined width of all garages, driveways, and off-street parking areas does not exceed a total of
60 percent of the length of the street frontage property line. This standard applies to buildings and
not individual units; or
b. The garage, driveway, or off-street parking area is separated from the street property line by a
dwelling; or
c. The garage, driveway, or off-street parking is located more than 100 feet from a street.
3. All detached garages and carports shall not protrude beyond the front building fagade.
4. The total width of all driveway approaches shall not exceed 32 feet per frontage, as measured at the
property line. Individual driveway approaches shall not exceed 20 feet in width.
5. Local jurisdiction requirements for driveway separation and access from collector streets and arterial
streets shall apply.
Dwelling Unit
Dwelling Unit Dwelling Unit Dwelling Unit
-------- --------
- -- - -
Dwelling Unit
�-
EntryG1
—
EntryG2—� G3 Ent -
Entry Entry G1
l
Entry G2�
g
8 `� Individual
Individual
a
i
Driveway
Driveway
<—DI—�
�D2�FD3: j Dl
D2=
Eoi rron[age _ �_ nor rronitaye
\i \ Sidewalk % \ \, Sidewalk
Street Street
(G 1+G2+G3)
Lot Frontage must be no more than 60%
(D1+D2+D3) must not exceed 32 feet per frontage
Individual driveway width (any "D#") shall not exceed 20 feet
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H. Landscaping Development regulations for landscaping and tree standards for middle housing shall be
equally or less restrictive than those required for detached single-family residences.
Tier 3 Cities
Entries. Each building shall incorporate a primary building entry or one or more private unit entries, such as a
covered porch or recessed entry. Each entry shall feature minimum weather protection of three feet by three
feet.
J. Windows and doors. A minimum of 15 percent of the area of the street -facing fagade elevation shall include
windows or doors. Facades separated from the street by a dwelling or located more than 100 feet from a
street are exempt from this standard.
N OF
Full,
Area subject to facade
transparency requirement
0 Qualifying window coverage
Qualifying door coverage
Local Policy Choice
Single -Family Design Standards
Cities may consider applying the same types of design standards in the Model Ordinances to detached single-
family residences. Some tailoring may be required for applicability and context.
Cottage Housing
Size Limit
The maximum cottage size of 1,600 square feet can be modified to fit local circumstances. RCW
36.70A.681(1)(f) states that city and counties may not establish maximum gross floor area limits for
accessory dwelling units less than 1,000 square feet. A cottage housing floor area limit above 1,000 square
feet would be reasonable. Because the model ordinance sets a maximum square foot standard, cottage
housing is exempt from floor area ratio limits in Section 7 of the Tier 1 and 2 Cities Model Ordinance.
Common Open Space
Common open space traditionally serves as the social and recreational center of cottage developments.
"Common open space' is referenced in the definition of "cottage housing" and will need to take up much of the
minimum 20 percent open space requirement, which also can include private open space, setbacks, natural
features, critical areas, and other open space. Key aspects of common open space include:
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Requiring that cottages are oriented around the common open space.
Minimum size standards to provide a minimum usable common open space area scaled to the size of the
development. The minimum 15 feet dimension is important to ensure the common open space is usable
for residents.
The minimum amount of open space per cottage can be variable; 300 square feet is more appropriate for
small infill lots, but larger minimums, such as 400 square feet, is a common standard required by cities that
regulate cottages.
Private Open Space
In addition to common open space, some cities require private open space for individual cottages. This may be
required at the front or rear of a cottage and typically is encouraged to be located between a cottage and
common open space and is not allowed to be at the side of a cottage. A minimum requirement of 200 square
feet per cottage is typical, along with minimum dimensional and useability standards that are similar or relaxed
compared to those for the common open space.
Porch Requirement
The entry standard, which requires a roofed porch on each cottage, helps cottages be compatible with the
form and character of typical low -density neighborhoods.
Community Buildings
The integration of community buildings is popular in many cottage developments and thus important to allow
in larger cottage housing developments. Because cottages are size -limited compared to typical detached
single-family residences, a community building can further promote livability and social activity in the
development with a range of shared uses, ranging from tool and furniture storage to community kitchens,
libraries, and recreation rooms.
Danielson Grove Cottages in Kirkland. Note the mix of private (landscaped areas in front of the cottages) and common (lawn area plus the
patio) open spaces and community building example (right image). Source: MAKERS.
Attached Cottages
Cities should consider allowing attached cottages, which comply with the other features of cottage housing
but may include clusters of duplex or triplex -style buildings. This arrangement creates more room for common
open space and helps improve energy efficiency, while supporting the community -oriented goals of some
cottage housing developments.
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Courtyard Apartments
Courtyard apartments is one of the middle housing types defined by RCW 36.70A.030.69 Particular design
features are included in the definition, The definition states that courtyard apartments have dwelling units
arranged on two or three sides of a yard or court.
Because courtyard apartments are defined by a yard or court, common open space standards are provided in
the model ordinances. There is also an entry standard which allows unit entries to face either the street or the
common space.
Pedestrian Access
A pedestrian access standard ensures clear and accessible pedestrian routes are provided between buildings
and streets. A paved pedestrian connection, as opposed to unpaved, is important to ensure that pedestrian
access is permanently available to provide safe and reliable pedestrian access for people using mobility
devices and for deliveries and emergencies (i.e., carts and gurneys). If a middle housing building is located at
the back of a lot or has alley access, the pedestrian access standard also ensures that residents and visitors
have easy access to the street and access to vehicles parked on -street.
The standard is also written with flexibility in mind. Driveways, which are often walked upon and already
connect a building and a street, may be used to meet the standard instead of a separate paved connection
The standard does not preclude the use of ramps or stairs.
Note that the standard provides an objective measurement of three feet minimum width for the paved
connection. Cities may require increased width to meet Americans with Disabilities Act (ADA) standards, and
larger middle housing developments with more foot traffic on a shared pedestrian connection may warrant a
wider pathway.
Vehicle Access, Carports, Garages, and Driveways
This set of standards related to vehicle access, garages and carports is adapted from the Oregon middle
housing model ordinances. This standard seeks to balance the practical need for vehicular access while
prohibiting designs that are dominated by multiple garages and driveways along a street, which can have
significant impacts on the walkability and visual character of residential neighborhoods.
The model ordinances include a standard that prevents designs like these with excessive driveway widths and garage dominated designs.
Source. MAKERS.
69 RCW 36.70A.030(10)
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The standard anticipates two scenarios: lots with alley access or no alley access.
Alley Access
Alley access is preferred because it allows vehicle parking, services, and utilities to be collected in the rear of a
development and create a more continuous and walkable streetscape in front of the lot. The alley access
requirement applies to "an improved alley that meets the city's standard for width." This standard does not
distinguish between whether the alley is or is not paved since some cities do not require paving or may have
pre-existing alleys that are not paved. Alleys that are platted but unbuilt, steep, or have other accessibility
issues likely would not be considered "improved" by most cities.
No Alley Access
Because many cities and neighborhoods do not have alleys, the standard also provides requirements for lots
that need to take vehicular access from a street. The first preference is that garages and off-street parking
areas be screened from the street by a building with dwelling units; for example, a townhouse development
may have garages on the bottom of each unit that are accessed from the rear of the building by a shared drive
that connects to the street in front. However, not every middle housing configuration and lot can physically or
economically accommodate this. When parking cannot be screened and must be visible from the street, the
model ordinance recommends that the width of off-street parking areas be limited in relation to the length of
the lot's street frontage. If a garage or off-street parking area is located more than 100 feet from a street it
would be exempt from this standard.
Covered Entries
The Model Ordinance for Tier 3 Cities provides for covered entries. Covered entries lend a sense of human
scale to homes. The three-foot dimension allows a resident to open a locked door out of the rain.
Windows and Doors
The Model Ordinance for Tier 3 Cities provides a design standard that at least 15 percent of the area of the
street -facing fagade elevation include windows or doors. This type of standard is a common requirement that
orients dwelling units towards the street and provides "eyes on the street" for safety. Note that it does not
specify that doors need to be transparent to qualify. Whereas the 15 percent standard is relatively common for
those communities that regulate fagade transparency, allowing doors to qualify offers flexibility. Cities can
consider adding additional language which clarifies garage doors do not qualify towards the 15 percent
minimum, considering one of the purposes of the design standards is to de-emphasize garages and driveways
Unit Articulation Standards
Faqade articulation standards for townhouses and multifamily development help reduce the perceived scale of
multi -unit buildings and add architectural variety and visual interest. Thus, cities might consider applying
similar standards for middle housing. Articulation standards are particularly helpful for compatibility for larger
middle housing buildings where multiple entries are visible from the street. By providing clear and objective
options, an articulation standard can meet the requirement to not affect the generally allowed density, height,
bulk, or scale of middle housing.
Below is an articulation standard developed for middle housing purposes. It is titled "Unit Articulation" since it
applies only to multi -unit buildings facing the street and featuring separate ground level entrances.
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X. Unit articulation.
1. Applicability.
a. Each attached unit featuring a separate ground level entrance in a multi -unit building facing the
street shall include at least one of the articulation options listed in subsection (X)(2) below.
b. Facades separated from the street by a dwelling or located more than 100 feet from a street are
exempt from this standard.
2. Articulation options:
1. Roofline change or a roof dormer with a minimum of four feet in width.
2. A balcony a minimum of two feet in depth and four feet in width and accessible from an interior
room. 70
3. A bay window that extends from the fagade a minimum of two feet. 71
4. An offset of the fagade of a minimum of two feet in depth from the neighboring unit.
5. A roofed porch at least 50 square feet in size.
Option 1
Option 3
Option 2
Option 4
Option 5
70 "Balcony" refers to a platform that projects from the wall of a building and is surrounded by a railing or balustrade.
71 A "bay window' is a window placed on an extension from an exterior wall.
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Minimum Usable Open Space
Many cities that allow for small lot detached single-family development or middle housing development require
some form of minimum usable open space. Such standards can bring extra protection beyond basic setback
requirements and minimum lot coverage to ensure that each unit has on -site open space that meets a
minimum dimension. s
For cities allowing up to two units on a lot, consider a standard that requires open space equivalent to at least
10 percent of the lot area with a minimum dimension of 15 feet on all sides of the open space. Each unit must
have direct access to the open space.
Where the lot density exceeds three units, consider a minimum 10 feet or 12 feet dimension to accommodate
more flexibility, while ensuring a minimum usable dimension.
For stacked flats and buildings with four to six units more flexibility is warranted, as direct access to a ground
level open space may not be possible. Thus, provisions for common open space that is physically accessible
to each unit will be important. Private balconies and shared roof decks can also be open space resources that
enhance the livability of middle housing.
Given space limitations on small lots and lots with two or more units, it is important to provide the opportunity
to locate usable open space in the front yard. Front yards in many single-family neighborhoods are seldom
used. However, front yards defined by a low fence, particularly when combined with a front porch, can make for
effective usable yard space.
Front yards and porches can be a particularly good source of usable open space for middle housing. Source: MAKERS
Design Standards Departures
Cities also have an option to offer departure requests to middle housing design standards. Departures should
only be made available if processed administratively and where a clear and objective design standard is
provided as the starting point that provides a straightforward path to compliance. Applicants seeking
departures volunteer to depart from an objective standard. In order for the planning director or their designee
to evaluate a departure request, clear purpose statements must be provided for each design standard and
additional criteria could be added for specific departure opportunities.
Example text for departure criteria is below.
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Departures are available for all design standards herein. Departures provide applicants with the
option of proposing alternative designs when the applicant can demonstrate a design is equal to or
better for meeting the 'purpose" of a particular standard.
b. Departures shall be administrative and reviewed, approved, or denied by the planning director or the
planning director's designee.
c. The planning director must document the reasons for all departure decisions within the project
application records.
As a land use decision, design departures are subject to both administrative appeal and possibly judicial
appeal under RCW 36.70C. The administrative appeal period is subject to the city's local regulations.
Discussion
House Bill 1293 and Design Review
If a city applies design review to middle housing, RCW 36.70A.635(6)(a) requires that only administrative
design review be used. Administrative design review must follow the standards of RCW 36.70A.630, which was
established in 2023 under House Bill 1293. Cities and counties must adopt regulations implementing RCW
36.70A.630 within six months of their next periodic comprehensive plan update.
With limited exceptions, such as for listed historic structures, the new requirements apply to development
projects for which a city conducts design review, and whether the design review process is administrative
(conducted by city staff) or public (conducted by a design review board).
The key requirement is that the design review process may only apply "clear and objective development
regulations" which govern the exterior design of new development. A "clear and objective" development meets
the following criteria:
1. Must include one or more ascertainable guideline, standard, or criterion by which an applicant can
determine whether a given building design is permissible under that development regulation; and
2. May not result in a reduction in density, height, bulk, or scale below the generally applicable development
regulations for a development proposal in the applicable zone.
The design standards in Section 8 of the Model Ordinances and User Guide are compliant with these criteria.
Administrative Design Review
Administrative design is defined by the GMA as:
"...a development permit process whereby an application is reviewed, approved, or denied by the planning
director or the planning director's designee based solely on objective design and development standards
without a public predecision hearing, unless such review is otherwise required by state or federal law, or
the structure is a designated landmark or historic district established under a local preservation
ordinance. A city may utilize public meetings, hearings, or voluntary review boards to consider,
recommend, or approve requests for variances from locally established design review standards." (RCW
36.70A. 030(3))
The design standards provided in the Model Ordinance and User Guide are objective and measurable and are
written to be efficient for staff to implement if the Model Ordinance, especially if the city does not adopt middle
housing regulations by the city's statutory deadline. Administrative design review is to be reviewed and
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decided by a planning director or their designee, with the exceptions noted in the definition. Informational
resources about design review implementation are listed at the end of this chapter.
Exceptions to administrative design review may be made in cases where review is required by state or federal
law, or if the structure is a designated landmark or within a historic district established by a local preservation
ordinance. Public meetings, hearings, or voluntary design review boards may also be used to consider,
recommend, or approve requests for variances from locally established design review standards.
As a land use decision, administrative design review is subject to both administrative appeal and possibly
judicial appeal under RCW 36.70C. The administrative appeal period is subject to the city's local regulations.
Trees
RCW 36.70A.635(6)(b) provides that "tree canopy and retention
requirements" shall not be more restrictive for middle housing than for
detached single-family residences. Other tree related development
standards may include, but are not limited to, significant tree
preservation, planting of new trees, and tree maintenance.
Trees provide considerable benefits to a community, including
stormwater management, noise buffering, soil erosion reduction,
supporting climate change strategies, providing habitat, and fostering
aesthetics. Additionally, as noted by the environmental organizations
focus group, trees are an equity issue with lower -income
neighborhoods tending to have less tree canopy than higher -income
Example of a new middle housing
development that is protecting existing
trees. Source: MAKERS
neighborhoods. Many communities have adopted urban forestry
regulations to address the planting, maintenance, care, and protection of tree populations.
Rather than have the model ordinances offer specific prescriptive recommendations for tree preservation and
retention for one use (or subgroup of uses) like middle housing, cities should consider developing a
comprehensive tree regulation strategy that thoroughly reviews, considers and updates existing tree
regulations as a broader package across all uses and type of permit applications. Tree regulations should seek
to balance and consider housing and environmental goals like climate change and air quality, local benefits of
mature trees, voluntary and other tree planting programs, and available administrative and enforcement
resources.
Some cities have tree standards that promote maintaining or growing the overall tree canopy, rather than
focusing on individual trees. For example, Port Orchard's McCormick Village Overlay District requires a plan
that achieves a minimum 25 percent tree canopy coverage in 20 years upon maturity of the trees. Significant
tree retention is only required if the significant tree is located with any perimeter landscaping requirement,
critical area protection areas, and required buffers.72
References
Design review
• Design Review, American Planning Association (collection of knowledge resources)
• Design Review: Guiding Better Development, American Planning Association (publication)
72 POW 20.38.280
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• Design Review in the Pacific Northwest, American Planning Association (conference session)
• Design Review, Municipal Research Service Center
• Short Course on Local Planning, Department of Commerce (see the special topic videos on infill
development for small cities)
Examples of small city design standards
• Port Angeles Residential Infill Design Standards (Chapter 17.21 PAMC)
• Anacortes Housing Type Design Standards (AMC 19.43.010)
Trees
• Urban Forestry, Municipal Research Service Center
• Redmond Tree Protection Ordinance (RMC 21.72)
• Olympia Tree, Soil, and Native Vegetation Protection and Replacement Standards (OMC 16.60)
• Seattle's 2023 Tree Protection Ordinance — Ordinance 126821
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2.9 — Parking Standards
Section 9 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
A. Off-street parking for middle housing shall be subject to the following:
1. No off-street parking shall be required within one-half mile walking distance of a major transit stop.73
2. A maximum of one off-street parking space per unit shall be required on lots smaller than 6,000 square
feet, before any zero lot line subdivisions or lot splits.71
3. A maximum of two off-street parking spaces per unit shall be required on lots greater than 6,000 square
feet before any zero lot line subdivisions or lot Splits.71
B. The provisions of subsection (A) do not apply to:
1. Portions of the city for which the Department of Commerce has certified a parking study in accordance
with RCW 36.70A.635(7)(a), in which case off-street parking requirement shall be as provided in the
certification from the Department of Commerce.76
2. Portions of the city within a one -mile radius of a commercial airport in Washington with at least
9,000,000 annual enplanements in accordance with RCW 36.70A.635(7)(b).7 78
Local Policy Choice
Number of Parking Spaces Required per Unit
The Model Ordinance uses the off-street parking requirements of RCW 36.70A.635(6)(d) through (f)
However, in establishing off street parking requirements for middle housing, cities should give consideration to
how off-street parking may occupy land area that could affect middle housing site design, especially on
smaller lots, as well as affect project affordability through the costs associated with developing parking. Off-
street parking requirements can also affect unit count of a middle housing project and be a deciding factor in
whether a middle housing project is or is not built.
For these reasons, it is recommended that cities consider at most a minimum parking requirement of one
space for middle housing unit, regardless of lot size. This is the same as the one -space maximum a city can
73 RCW 36.70A.635(6)(d). This standard applies only to middle housing, not all development. However, elimination of adjustment of
other parking standards near major transit stops is encouraged. See the local policy choice and discussion sections
74 RCW 36.70A.635(6)(e)
75 RCW 36.70A.635(6)(f)
76 RCW.70A.635(7)(b) The Department of Commerce is working on guidance for this provision which will be completed by May 1, 2024.
77 This only applies to Seattle -Tacoma International Airport. Enplanement data is provided by the Federal Aviation Administration:
https://www.faa.gov/airports/planning_capacity/passenger_al Icargo_stats/passenger
78 RCW.70A.635(7)(b) The Department of Commerce is working on guidance for this provision which will be completed by May 1, 2024.
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require on lots less than 6,000 square feet, but is less than the two -space maximum a city can require on lots
greater than 6,000 square feet in size. One parking space per middle housing unit, regardless of lot size, can
improve the physical and economic feasibility of developing middle housing.
Lots exactly 6,000 square feet in size are not addressed by RCW 36.70A.635(6)(e) and (f). Cities that choose to
provide different parking requirements based on lot sizes being less than or greater than 6,000 square feet
may choose whether to apply RCW 36.70A.635(6)(e) or RCW 36.70A.635(6)(f). Again, it is recommended that
cities require no more than one parking space per middle housing unit in general, including lots exactly 6,000
square feet in area.
Affordable Housing
Affordable housing is difficult to finance without subsidy, and off-street parking represents a substantial cost
of developing housing. Households who might occupy HB 1110 affordable housing units may own fewer
vehicles than moderate- and higher -income households.79 Cities should consider eliminating off-street parking
requirements for affordable housing units.
Major Transit Stops
See User Guide Chapter 3.2 for guidance on how walking distance to major transit stops may be measured
Other State Law Parking Requirements
HB 1337, passed in 2023, has parking requirements for accessory dwelling units which are similar to what
RCW 36.70A.635 provides for middle housing. See RCW 36.70A.681(2). For the purposes of parking
requirements for accessory dwelling units, under RCW 36.70A.696(8) there is a slightly different definition of
"Major transit stop" than for middle housing.
RCW 36.70A.620 has provisions on the amount of parking that can be required near certain types of transit for
various types of affordable housing, housing for seniors and people with disabilities, and market rate
multifamily units. The standards in RCW 36.70A.620 do not conflict with the standards of RCW 36.70A.635 or
the Model Ordinances, but they should be reviewed so that in instances where there may be overlap, required
off-street parking is consistent with both RCW sections.
Exemptions
The off-street parking standards of RCW 36.70A.635(6) do not apply in two situations:
If a city submits to Commerce an empirical study prepared by a credentialed transportation or land use
planning professional that clearly demonstrates, and Commerce finds and certifies, that middle housing
parking required by HB 1110 would be significantly less safe for pedestrians, bicyclists, or people in
vehicles than if the jurisdiction's parking requirements were applied to the same location for the same
number of detached houses.80 Commerce will develop guidance for this exemption by May 31, 2024.
79 "Socioeconomics of urban travel in the U.S.: Evidence from the 2017 NHTS." Transportation Research Part D: Transport and
Environment, Volume 116, 2023. https://www.sciencedirect.com/science/article/pii/Sl361920923000196?via%3Dihub
80 RCW.70A.635(7)(a)
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In portions of cities within a one -mile radius of a commercial airport in Washington with at least 9,000,000
annual enplanements, in accordance with RCW 36.70A.635(7)(b).81 This only applies to Seattle -Tacoma
International Airport, according to enplanement data provided by the Federal Aviation Administration.82 ;
Cities not planning to employ the "empirical study" exemption, and cities located further than one mile from
applicable airports, have the option to not adopt Model Ordinance Section 9, subsection (B).
On -Street Parking Credit
To add flexibility and reduce construction costs, cities may
consider allowing on -street parking to be credited toward any
minimum off-street parking requirements. This approach is
provided in the Oregon middle housing model codes. The credit
could be written with the following types of standards intended
to promote on -street parking in appropriate locations.
X. If on -street parking spaces meet all of the following
conditions they shall be counted toward the minimum off-
street parking requirement for middle housing.
1. On -street parking is allowed and abuts the subject site.
2. The space must be a minimum of 20 feet long.83
Street parking in a residential neighborhood. Source:
MAKERS.
3. The space must not obstruct a required sight distance area.
4. The on -street parking shall not be deeded, or for exclusive use, to any property.
Conversions
To encourage preservation and rehabilitation of existing structures, cities may consider exempting off-street
parking requirements for middle housing conversion projects up to a certain size. This would allow greater
flexibility for conversions or additions where the existing building placement makes it difficult or not possible
to add new parking. The following provision would address common conversion proposals:
X. No additional off-street parking shall be required for conversion of a detached single-family residence
to a middle housing type with up to four units (whether additional units are attached or detached with the
original structure).
81 RCW.70A.635(7)(b)
82 "Passenger Boarding (Enplanement) and All -Cargo Data for U.S. Airports." Federal Aviation Administration.
https://www.faa.gov/airportsiplanning_capacity/passenger_al Icargo_stats/passenger
83 Item (2) could be revised to the standard length of a parallel parking space in the city if it is different than 20 feet.
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Covered Parking
To allow greater flexibility and to reduce the cost of providing housing, cities may consider not requiring that
parking be covered or indoors. Outdoor parking is common in residential neighborhoods.84 This could be
addressed by adopting an additional subsection: c
X. Parking for middle housing shall not be required to be located within a garage, carport, or other
structure.
Discussion
Eliminating Off -Street Parking Requirements
Beyond one-half mile distance of a major transit stop, jurisdictions may consider eliminating minimum off-
street parking requirements entirely for middle housing (and other residential land uses) to reduce the costs
and physical complexity of providing housing and reduce the costs of owning and renting housing.
Off-street parking takes up land area and can create both physical and economic feasibility barriers to middle
housing development. Reducing parking requirements can prove extremely helpful in supporting diverse
housing types at lower price points. This is particularly an opportunity where local transit service is strong, bike
and pedestrian infrastructure is well-connected, and residential areas are within close proximity to jobs centers
and shopping areas. Builders can continue to build parking at their discretion to meet market demand even
without regulatory requirements for parking.
The cost of providing surface parking can increase the per -unit construction cost of middle housing between
approximately $5,000 and $50,000 depending on the type of parking, number of stalls required, drive aisle area,
and turnaround space. Enclosed parking spaces can add even more costs to the construction cost of a
housing unit depending on the level of conditioning and finishing requirements.
In addition, off-street parking can create significant physical barriers to middle housing development on infill
sites, especially when space limitations require that parking be located in what would otherwise be buildable
area for the structure. These physical limitations translate to economic impacts to development feasibility and
financial yield that can cause middle housing to be built at lower densities or not be feasible at all.
In summary:
• Parking is expensive. Parking space construction ranges from $5,000 - $6,000 a stall for surface parking,
$20,000 - $25,000 a stall for above ground structured parking, and $30,000 - $50,000 a stall for
underground parking (Cascadia Partners. 2023; VTPI. 2022; & City of Lacey. 2021).
• High parking mandates negatively impact the financial feasibility of middle housing development.
• High parking mandates are spatially difficult to fit on a lot and compete against livable and open space.
• Parking is a popular amenity and developers will often choose to include off-street parking in middle
housing projects where feasible.
84"One in Three Garages Has No Car in It." Sightline Institute, 2022. https://www.sightline.org/2022/04/27/one-in-three-garages-has-
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SEPA Exemption
HB 1110 amends RCW 43.21 C.495, a section of the State Environmental Policy Act (SEPA). It adds subsection
(6) that states:
The following nonproject actions are categorically exempt from the requirements of this chapter:
(6) Amendments to development regulations to remove requirements for parking from development
proposed to fill in an urban growth area designated according to RCW 36.70A.110.
This means implementation of subsection (A)(1) in Model Ordinance Section 9, which removes minimum
parking requirements within one-half mile of major transit stops, does not require SEPA review. It also means
that other actions which go beyond subsection (A)(1), such as removing minimum parking requirements for
any use and in any location within an urban growth area, do not require SEPA review.
Parking with Zero Lot Line Subdivision and Lot Splits
RCW 36.70A.635(6)(e) and (f) establish parking requirements based on lot size "...before any zero lot line
subdivisions or lot splits."
A "lot split" is a type of subdivision intended to streamline the typical subdivision process and/or allow for a
minimum of two housing units on the same land presently occupied by a single housing unit, and/or allow the
creation lots that are less than the minimum lot size required in a zone. The concept has gained recent
attention after California authorized lot splits starting in 2022.81
In Washington state law a "lot split" is undefined and there is currently no authorization or requirement for
allowing lot splits. Therefore, at the time of publication in January 2024, this User Guide does not provide any
guidance for cities on responding to the lot split references in in RCW 36.70A.635(6)(e) and (f).
The term "zero lot line" is used in several times in RCW 36.70A.635. State law does not define "zero lot line" nor
"zero lot line subdivision." Cities should interpret "zero lot line" to mean the physical state of a building located,
or permitted to be located, on one or more property lines on a lot. This state can be achieved where a zoning
setback requirement is zero feet, within an attached townhouse development, in a unit lot subdivision, or
through other code mechanisms.
References
• Cost per space for parking (Cascadia Partners, 2023; VTPI, 2022; & City of Lacey, 2021).
• Middle Housing Implementation Pro -Forma Calibration and Assumptions (Cascadia Partners)
• Middle Housing Implementation Pro -Forma Sensitivity Testing (Cascadia Partners, 2023)
• Portland Middle Housing Case Study (Cascadia Partners, 2023, pg. 27)
• City of Olympia Washington reduces parking minimums for all residential units Ordinance 7366 (2023)
• A Business Case for Dropping Parking Minimums, 2022, Planning Magazine
• Parking Reform Network
85 "SB 9 Fact Sheet." California Department of Housing and Community Development. https://www.hcd.ca.gov/docs/planning-and-
community-development/sb9factsheet.pdf
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2.10 — Infrastructure Standards
Section 10 Model Ordinance Text
The Model Ordinance text is copied below for reference. Footnotes may have been added to the model
ordinance text in this User Guide to provide supporting information. Refer to User Guide Chapter 1.3 for
information on the difference between bold text and non -bold text.
A. Transportation. Regulations for driveways, frontage improvements, alley improvements, and other
transportation public works and engineering standards shall not be more restrictive for middle housing than
for detached single-family residences, except as addressed by this ordinance.
B. Lot Access/Road Standards.
Private driveway access shall be permitted for middle housing development with any number of units
when a fire apparatus access road is within 150 feet of all structures on the lot and all portions of the
exterior walls of the first story of the buildings, as measured by an approved route around the exterior of
the buildings.
2. When a fire apparatus road is not within 150 feet of all structures on the lot, subsection (B)(1) does not
apply and one of the following conditions must be met:
a. The building is equipped throughout with an approved automatic sprinkler system meeting
International Fire Code requirements.
b. No more than two units are accessed via the same private driveway.
c. Fire apparatus access roads cannot be installed because of location on property, topography,
waterways, nonnegotiable grades or other similar conditions, and an approved alternative means of
fire protection is provided.
3. Private driveways shall not be required to be wider than 12 feet and shall not be required to have
unobstructed vertical clearance more than 13 feet six inches except when it is determined to be in
violation of the International Fire Code or other fire, life, and safety standards, such as site distance
requirements.
4. Private driveway access, separate from access to an existing home, shall be permitted unless it is
determined to be in violation of the Fire Code or other fire, life, safety standards, such as site distance
requirements.
5. This subsection is not intended to limit the applicability of the adopted fire code, except as otherwise
presented in this subsection.
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Discussion
Public works and infrastructure standards that create conditions on development are a "development
regulation" subject to RCW 36.70A.635(6)(b). This is supported by the definition of "development regulations"
under RCW 36.70A.030.
To comply with RCW 36.70A.635(6)(b), public works and infrastructure development standards cannot be
more restrictive for middle housing than for detached single-family residences.
However, some level of discretion is appropriate to account for functional and utilitarian differences between
middle housing and detached single-family residences and to promote public health, safety, and welfare.
Differences in standards are most appropriate when they are based on the number of dwelling units (not based
on the specific type of residential building). Differences are also appropriate where a middle housing
development is large (e.g., more than 12 units) and begins to have similarities to multifamily development,
which has greater impacts and larger economies of scale that can absorb additional costs.
Examples and further considerations are below.
Street Frontage and Alley Improvements
The standard of RCW 36.70A.635(6)(b) means, for example, that permitting for a fourplex cannot be
conditioned upon an unpaved alley being paved or curb, gutter, and sidewalk being provided on a street
frontage if a detached single-family residence on the same lot would not have the same condition.
However, street frontage and alley improvements could be required based upon technical metrics such as the
number of PM peak hour vehicle trips estimated to be generated by a development. For example, one city in
Washington requires that where a sidewalk is missing in front of a lot proposed for development the sidewalk
must be provided if the development will generate 10 or more PM peak hour vehicle trips.
Cities should also consider addressing deficiencies in their pedestrian and bicycle networks in areas where an
increase in density is expected as a result of complying with RCW 36.70A.635. City -led projects, such as
creating an entire block of new sidewalk, can often result in better mobility outcomes than waiting for
piecemeal improvements contributed by individual private developments.
Lot Access/Road Standards
Cities may need to adjust their standards for shared access provisions, particularly for those lots that don't
have direct access to a public right-of-way. The Model Ordinance sets a base minimum width for such a
shared access lane of 12 feet and seeks to ensure that such shared access lanes meet International Fire Code
requirements. Cities should review current private road or driveway access standards to see if they would
accommodate development of one or more housing units in the rear of a lot when the existing home is
retained. Are the required widths narrow enough to accommodate access between the side property line and
existing house? Do current standards allow the number of units required to be allowed under RCW
36.70A.635(1)? Are there other road standards that might need to be adjusted to work when applied to small
lot development?
Water and Sewer
Water and sewer utility purveyors (cities, special districts, and private purveyors) should have flexible
requirements for the design of water and sewer connections to middle housing lots and buildings. There are
advantages and disadvantages to centralized and shared lateral connections and metering, and there may be
different ownership arrangements, cost implications, and other reasons that require a variety of approaches.
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For example, a sixplex developer should be able to choose between having a master meter maintained by a
homeowner's association and having separate meters for each unit.
When development occurs on a larger lot and the lots resulting from that development can be redeveloped
under RCW 36.70A.635, consider requiring installation of water and sewer lines that are sized to accommodate
future redevelopment on each lot. This may not be necessary if the lots created are small enough where
redevelopment would not be possible.
Stormwater
Stormwater runoff is produced when precipitation falls on impervious surfaces and flows into storm drains
and streams. Impervious surfaces include building roofs and pavement. Some configurations of middle
housing are relatively compact and do not necessarily increase impervious surface area beyond that of a
typical detached single-family residence, and so the impact of redeveloping individual lots may be minimal.
Allowing tall structures and requiring little or no surface parking/driveways can potentially reduce impervious
surface in general. Because many Washington cities were developed before modern stormwater controls, new
development tends to improve stormwater treatment because it includes modern infrastructure.
Cities should also allow on -site and off -site mitigation options when impervious surface resulting from middle
housing development could approach or exceed the limitations for a stormwater system. For example,
allowing pervious paving and grasscrete for driveways; reducing the amount of required off-street parking;
allowing for vegetated roofs, rain gardens, and bioswales which capture or slow stormwater; allowing off -site
strategies such as converting unused on -street parking to landscaped areas; allow the building of rain gardens
or bioswales such as parks or street planter strips; or allowing modification or expansion of existing
stormwater facilities to accommodate additional development.
Note that most development of 5,000 square feet or more of impervious surface on a lot triggers more
requirements for on -site stormwater treatment.
Solid Waste
Because trash is a public health and safety concern, it is
reasonable to have solid waste standards that scale with the
size of development. Large numbers of bins can also be a
transportation concern, especially for people walking. Larger
middle housing developments may be required to provide a
centralized trash dumpster area meeting environmental
protection standards instead of each unit being permitted to
have individual trash bins.
References
Solid waste bins in an alley for a six -unit townhouse
development. Source: MAKERS.
• King County Capacity Charge. Example of a utility fee which is graduated based on the size and type of
residential dwelling.
• Department of Ecology municipal stormwater permits. Information on what types of stormwater
requirements are in place for jurisdictions across the state.
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3.0 - Additional Considerations
3.1 — Existing Zones and Overlay Zones
To implement RCW 36.70A.635, cities have the option: to: (1) amend their existing zones; (2) create a "middle
housing overlay zone"; or (3) create a new zone or zones. There are advantages and disadvantages to each
approach.
Amending Existing Zoning
Cities may choose to change allowed uses, density limits, and other standards in existing residential zones to
comply with RCW 36.70A.635. In a typical zoning district predominantly for residential use and where only
detached single-family residences are currently allowed, the zoning district's allowed uses must be amended
to allow middle housing in general or specific middle housing types.
The existing dimensional standards and other standards in the zone may be retained to apply to both detached
single family residences and middle housing. However, pre-existing dimensional standards may be poorly
suited to desired middle housing outcomes. For example, large building setbacks and low building height
requirements could make middle housing development challenging, especially on smaller lots. At the same
time, adjusting standards for both single-family and middle housing types could allow significantly larger
single-family homes (sometimes known as "McMansions") to be built. This can be mitigated by allowing more
generous standards for middle housing buildings. When updating dimensional standards, cities should look to
the applicable Model Ordinance for their tier for guidance.
In existing multifamily zones, cities will need to adjust density or minimum lot area per unit standards that
would preclude the required unit density for their tier on a typical lot, or to establish an exception to allow
middle housing to exceed the base maximum density.
Tier 1 / Tier 2
Tier 1 / Tier 2
Tier 3
Tier 3
2
5,000 SF
7,500 SF
5,000 SF
7,500 SF
17.4 dwelling units per acre
11.6 dwelling units per acre
34.8 dwelling units per acre
23.2 dwelling units per acre
2
4
4
Overlay Zones
A second option is the use of overlay zones. Creating a difference in dimensional standards between detached
single-family residences and middle housing is one reason cities may be interested in creating an overlay zone
with standards specific to middle housing. This has the advantage of organizing middle housing standards in a
separate code section, at the cost of increased complexity, with overlay provisions that would need to be
repeatedly cross-referenced throughout the code. Cities must also consider that every zone subject to RCW
36.70A.635 would need to be shown on the zoning map with an overlay symbol.
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New Zones
A third option is to create an entirely new zone or zones that complies with RCW 36.70A.635 to replace
existing low -density zones. This provides the opportunity to start with a clean slate and create standards well -
calibrated to deliver desired outcomes. Several Washington cities are already undertaking this effort in
conjunction with their comprehensive plan updates.
Zone Names
Some cities are also updating zone and land use designation names that eliminate the term "single family" in
favor of more generalized terms that emphasize development intensity. Examples include Residential 1,
Residential 2, etc., where the lowest number equates to the lowest density; or R-L, R-M, R-H, to emphasize low,
medium, and high density; or various versions of "Neighborhood Residential" zones.
3.2 - Major Transit Stops
Types of Major Transit
The definition of "Major transit stop" includes stops for at least the following types of transit systems:
• Light rail.
• Commuter rail.
• Amtrak.
• Streetcar.
• Monorail.
• Bus rapid transit.
• Trolley buses.
• Other transit funded or expanded under the provisions of chapter 81.104 RCW.
Note that for accessory dwelling units, under RCW 36.70A.696(8) there is a different definition of "Major transit
stop" than for middle housing.
Chapter 81.104 RCW
This chapter of the RCW is for high capacity transportation systems, which are defined in the chapter as "a
system of public transportation services within an urbanized region operating principally on exclusive rights -of -
way, and the supporting services and facilities necessary to implement such a system, including interim
express services and high occupancy vehicle lanes, which taken as a whole, provides a substantially higher
level of passenger capacity, speed, and service frequency than traditional public transportation systems
operating principally in general purpose roadways."
Chapter 81.104 RCW currently only applies to Sound Transit, which operates high -capacity transportation
systems in King, Pierce, and Snohomish counties including light rail, commuter rail, and intercity express
buses. All of the transit stops for Sound Transit services, including intercity express buses, are a major transit
stop.
Sound Transit is actively modifying its express bus system as light rail and bus rapid transit are built out.
Changes to the express bus system undergo public outreach and require the approval of the Sound Transit
Board of Directors. Occasionally, like other transit agencies, Sound Transit also administratively modifies
express bus routes and stops via the regular service change process. Cities in King, Pierce, and Snohomish
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counties should stay updated on Sound Transit's express bus service changes to ensure continued
compliance with RCW 36.70A.635.86
Fixed Guideway Systems
"Fixed guideway system" is not defined in the Growth Management Act (GMA) but is defined in the Washington
Administrative Code (WAC). Under WAC 173-424-110 fixed guideway means "...a public transportation facility
using and occupying a separate right of way for the exclusive use of public transportation using rail, a fixed
catenary system, trolley bus, streetcar, or an aerial tramway."
The trolley bus network operated by King County Metro is an example of a non -rail fixed guideway system
Bus Rapid Transit (BRT)
Bus rapid transit is not defined in the GMA, the Revised Code of Washington (RCW), or the WAC.
The Puget Sound Regional Council Regional Transportation Plan, which applies to the central Puget Sound
region (King, Pierce, Snohomish, and Kitsap counties) describes bus rapid transit as the following: "Bus rapid
transit (BRT) routes in the region are distinguished from other forms of bus transit by a combination of
features that include branded buses and stations, off -board fare payment, wider stop spacing than other local
bus service, and other treatments such as transit signal priority and business access and transit (BAT) lanes."
For further reference, the Federal Transit Administration defines BRT as: "Fixed -route bus systems that operate
at least 50 percent of the service on fixed guideway. These systems also have defined passenger stations,
traffic signal priority or preemption, short headway bidirectional services for a substantial part of weekdays
and weekend days; low -floor vehicles or level -platform boarding, and separate branding of the service.
Agencies typically use off -board fare collection as well. This is often a lower -cost alternative to light rai1.1187
This is consistent with a similar definition and BRT standards maintained by the Institute for Transportation &
Development Policy. 88
The following services operated by transit agencies in Washington are examples of BRT:
• King County RapidRide routes.
• Sound Transit Stride routes.
• Community Transit Swift routes.
• Spokane Transit Authority City Line.
• C-TRAN BRT routes.
86 See the Sound Transit "service changes" webpage for the latest information, including an email contact and subscription for service
changes. https://www.soundtransit.org/ride-with-us/changes-affect-my-ride/service-changes
87 "National Transit Database (NTD) Glossary." Federal Transit Administration. https://www.transit.dot.gov/ntd/national-transit-
database-ntd-glossary. See also: https://www.transit.dot.gov/research-innovation/bus-rapid-transit
88 "What is BRTT' Institute for Transportation & Development Policy. https://www.itdp.org/library/standards-and-guides/the-bus-rapid-
transit-standard/what-is-brt/
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Cities should consider going beyond the requirements of RCW 36.70A.635(1) near major transit stops and
permitting transit -oriented densities, multifamily housing, and a variety of non-residential uses. The
Department of Commerce provides many transit -oriented development (TOD) resources, including grant
funding for TOD planning and examples of TOD planning documents.89 See also the TOD page from the
Municipal Research and Services Center.90
Measuring Walking Distance
Cities with major transit stops (RCW 36.70.030(25)) must consider both
unit density increases, and specific middle housing parking requirements
based on distance to the major transit stop. Tier 1 cities must allow at
least six units per lot on all lots zoned predominantly for residential use
within one -quarter mile walking distance of a major transit stop while Tier
2 cities must allow at least four units per lot within one -quarter mile
walking distance of a major transit stop. For all cities subject to RCW
36.70A.635(1), no parking is required for middle housing within one-half
mile walking distance of a major transit stop.91
Cities can measure distances from major transit stops in at least two
different ways. Each method comes with advantages and disadvantages.
The chosen methodology should be identified in the code, perhaps within
a definition of "walking distance", to ensure the methodology is
consistently applied and measured over time. Inclusion of the walking
distance area on the zoning map, would offer greater certainty to
property owners and others as to which parcels are and are not included
in the walking distance requirements of a major transit stop. A potential
downside to this approach is the need to go through a procedural
process to amend the zoning map should the walking distance need to
be amended over time due to physical improvements that change the
walking distance or routes.
For both methods it is important to consider whether to place a center
point of the major transit stop or use the perimeter of the major transit
stop. In general, separate radii should be drawn for each boarding and
alighting point if they are separated by more than 100 feet, such as a
north -bound and a south -bound bus stops that are located at opposite
ends of a block. For large major transit stops, such as a rail station, the
most straightforward approach is to locate center points in the middle of
the station of platforms. However, the optimal approach should always
be determined using the best judgement of the jurisdiction.
Radius
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P men I Emill
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Path -Finding
Conceptual illustration of different
methods for measuring walking
distance. Source. MAKERS
89 https://www.ezview.wa.gov/site/alias-2000/37739/library.a3px
90 "Transit -Oriented Development." Municipal Research Service Center. https://mrsc.org/explore-topics/planning/development-types-
and-land-uses/transit-oriented-development
91 Walking at three miles per hour, a typical speed for an able-bodied person, means a one -quarter distance is a five-minute walk and a
half -mile distance is a ten-minute walk.
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Radius
In this approach, a circle is centered on the major transit stop and the radius of the circle is the required
distance (one -quarter mile or one-half mile). All lots zoned predominantly for residential use which are fully
within the circle should be applicable. Lots which are partially within the circle should also be applicable in
order to increase housing capacity near major transit stops, though a city can also set other criteria such as at
least 5O% of a lot or a minimum amount of lot area is in the circle for the lot to be included.
This method has the advantage of being easy to execute. A consideration is where precisely the circle is
centered for large major transit stops, such as a rail station; the approximate center of the stop or platforms is
most straightforward and avoids potential complexities with using pedestrian entrances and property
boundaries - however, this should be determined on a case -by -case basis using the best judgement of the city.
This method has the disadvantage of not accounting for conditions that can constrain walkability and reduce
the actual area that is in reasonable walking distance of the major transit stop, such as terrain, water bodies,
missing pedestrian routes, or infrastructure barriers. This disadvantage could be overcome by first drawing the
circle and then customizing it to remove areas which are not reasonably in walking distance due to local
conditions. Areas which are removed should have documentation explaining why they are exempt.
Path -Finding
In this approach, actual walking paths extending from a major transit stop for the required walking distance
(one -quarter mile or one-half mile) are mapped using a geospatial analysis of the local street network and
other pedestrian routes such as off-street trails. All lots zoned predominantly for residential use which touch
the walking paths are applicable.
This method has the advantage of more accurately capturing lots within actual walking distance of major
transit stops.
This method has the disadvantage of requiring access to geospatial analysis software and the skills, funding,
and time to employ it. This method also requires that the analysis be repeated from time -to -time to account for
changes to pedestrian infrastructure. In some cases, these disadvantages could be overcome by hiring an
outside consultant who specializes in geospatial analysis. Network analysis results created for this purpose
should be displayed on zoning maps and made available for download on public geographic information
system (GIS) databases, if possible.
This method has the disadvantage of requiring access to geospatial analysis software and the skills, funding,
and time to employ it. This method also requires that the analysis be repeated from time -to -time to account for
changes to pedestrian infrastructure. In some cases, these disadvantages could be overcome by hiring an
outside consultant who specializes in geospatial analysis.
Future Major Transit Stops
The definition of "Major transit stop" (RCW 36.70A.030(25)) and references to "Major transit stop" in RCW
36.70A.635 do not specify if or when to apply applicable requirements to future major transit stops which are
in planning or construction.
Should a new major transit stop be planned in a city with unit per lot and/or parking requirements related to
transit, then Commerce recommends that the unit per lot and parking requirements of RCW 36.70A.635 apply
to that new major transit stop but be implemented when the major transit stop is open for public use.
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A jurisdiction may plan for transit -oriented development around future major transit stops. The extent and level
of that planning may vary depending on the type of major transit stop. The opening of a light rail station may
be preceded by years of station area planning to identify land use and zoning designations. Bus rapid transit
facilities may involve a less elaborate and less detailed station area planning process.
Experience has shown that property acquisition and transit -oriented development may occur far in advance of
the opening of a major transit stop, particularly for high -capacity transit such as light rail. Cities should
consider adopting higher densities (above those required by RCW 36.70A.635) near and around major transit
stops to allow for a higher level of housing production, even in advance of the major transit stop opening.
For all major transit stops, implementation of parking requirement and unit per lot densities in RCW
36.70A.635 should be implemented as soon as the walking distance measurements can be accurately
determined. Final design of the major transit stop should provide sufficient information to determine the one -
quarter mile and one-half mile walking distances for lots subject to unit density and parking provisions in the
Model Ordinance (see User Guide Chapters 2.5 - Unit Density and Affordable Housing and 2.6 - Middle
Housing Types). At the very latest, it is recommended that implementation of unit density and off-street
parking requirements should occur no later than the opening of the major transit stop for use by the public.
3.3 — Declarations and Governing Documents
While cities may review declarations and governing documents as part of a subdivision process or other
development application, cities do not have the authority or obligation to enforce or invalidate them. Cities
should, however, be aware of the following new provisions in state law and could help educate property owners
and associations about these:
• Homeowners' association governing documents created after July 23, 2023, pursuant to Chapter 64.38
RCW may not actively or effectively prohibit the construction, development, or use of additional housing
units as required in RCW 36.70A.635.92
• Condominium declarations created after July 23, 2023, pursuant to Chapter 64.34 RCW may not actively or
effectively prohibit the construction, development, or use of additional housing units as required in RCW
36.70A.635.93
• Common interest community declarations and governing documents created after July 23, 2023, pursuant
to Chapter 64.90 RCW may not actively or effectively prohibit the construction, development, or use of
additional housing units as required in RCW 36.70A.635.94
• Association of apartment owners declarations created after July 23, 2023, pursuant to Chapter 64.32 RCW
may not actively or effectively prohibit the construction, development, or use of additional housing units as
required in RCW 36.70A.635.95
Existing declarations and governing documents cannot be amended in order to prohibit middle housing, but
different design standards could be applied to middle housing. As cities do not have the authority to
invalidate such declarations and governing documents, a challenge to a covenant would come from a third -
party lawsuit.
92 RCW 64.38.150
93 RCW 64.34.110
94 RCW 64.90.340
95 RCW 34.32.330
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3.4 - State Environmental Policy Act (SEPA)
Under RCW 36.70A.600(1), cities are also encouraged to amend local environmental regulations and take the
following actions to increase residential building capacity:
• Adopt a subarea plan pursuant to RCW 43.21 C.420
• Adopt a planned action pursuant to RCW 43.21 C.440(1)(b)(ii)
• Adopt increases in categorical exemptions pursuant to RCW 43.21 C.229 for residential or mixed -use
development.
• Adopt maximum allowable exemption levels in WAC 197-11-800(1)
The adoption of ordinances, development regulations and amendments to such regulations, and other non -
project actions taken by a city to implement any actions specified in RCW 36.70A.600(1), with the exception of
adopting subarea plans, are not subject to administrative or judicial appeal under SEPA (RCW 43.21 C).
3.5 - Building Code
Cities should be aware that structures with three or more units fall under the International Building Code (IBC)
and are subject to a more extensive and costly standards than one- or two -unit structures which fall under the
International Residential Code (IRC). The IRC applies to buildings with one or two dwelling units and
townhouses not more than three stories above grade and with a separate means of egress. The difference in
middle housing types covered by the two building codes will affect the construction and affordability of middle
housing types with three or more units in one structure.
Cities that want to increase flexibility should examine updating their locally adopted version of the IRC and IBC
to allow structures with up to six units to be built under the International Residential Code. Cities could also
consider supporting any future version of 2023 House Bill 1167, which would make middle housing related
building code changes for the entire state.
• A Trailblazing Reform Supports Small -Scale Development in Memphis." Strong Towns. January 2022.
• Memphis, TN Amends Local Building Code to Allow up to Six Units Under Residential Building Code (IRC) to
Enable Missing Middle Housing." Opticos Design. January 2022.
• State of North Carolina changes IRC to allow up to four units.
• The political movement to limit multifamily by limiting the IRC code (Strong Towns, 2023; Baar, 2007)
3.6 - Critical Areas
As mentioned earlier in the User Guide, RCW 36.70A.635(8)(a) states that the provision of RCW 36.70A.635 do
not apply to critical areas or their buffers. RCW 36,79A,030(11) identifies defines critical areas as:
• Wetlands
• Areas with a critical recharging effect on aquifers used for potable water
• Fish and wildlife habitat conservation areas
• Frequently flooded areas
• Geologically hazardous areas
This User Guide recommends that cities still allow for middle housing on critical areas, applying the city's
critical areas regulations to middle housing development.
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While the diversity of critical area types and extent of critical areas in a jurisdiction will vary, two critical areas
that have the possibility of taking up large areas of a jurisdiction residential (and non-residential) land area:
frequently flooded areas and aquifer recharge areas.
Frequently Flooded Areas
"Frequently flooded area" (FFA) is a critical area designation that can be applied by local jurisdictions to areas
with a known flood risk.
The Washington State Department of Commerce Critical Areas handbook states that frequently flooded areas
should include, at a minimum, the 100- year floodplain designations of the Federal Emergency Management
Agency (FEMA) and the National Flood Insurance Program (NFIP), known as the "special flood hazard area."
Many communities have incorporated the NFIP standards into their frequently flooded area codes and deem
this sufficient. This can meet the minimum requirements if there are no special circumstances. However,
FEMA maps do not address all of the flood risk in communities and frequently flooded area designation should
be based on best available science. Local governments are encouraged to consider additional flood risks in
their communities. For more information, see the Critical Areas Handbook.9e
Critical Aquifer Recharge Areas
Critical aquifer recharge areas (CARAs) are areas with a critical recharging effect on aquifers used for potable
water, including areas where an aquifer that is a source of drinking water is vulnerable to contamination that
would affect the potability of the water, or is susceptible to reduced recharge. The quality and quantity of
groundwater in an aquifer is inextricably linked to its recharge area.
The Commerce Critical Areas Handbook discusses the designation, classification and protection of CARA's.
Protection of CARA's may require additional precautions for land uses located in CARAs, particularly those
land use types that may have activities that could contribute to contamination of an aquifer. Examples might
include car -related uses with special concerns for petrochemical leaks, illegal dumping, tire piles, auto
graveyards, car washes, chemical storage, and warehousing. Protection of CARA's may also take the form of
existing groundwater protection programs for Sole source aquifer recharge areas, groundwater management
areas and source water/wellhead protection areas. For more information, see the Critical Areas Handbook.
Reasonable Use
In addition to specific types of critical areas, local government critical areas ordinances have reasonable use
provisions. Reasonable use permitting is a process that seeks to ensure that property owners can maintain a
minimum "reasonable use" of their property, despite restrictions that are imposed by critical areas restrictions
or other environmental laws. This process seeks to avoid a "taking" of property in contravention of rights
established in the Fifth Amendment and Fourteenth Amendment of the U.S. Constitution and interpreted
through decades of judicial rulings.
For residential zones, a minimal reasonable use may be a modest detached single-family residence, the size of
which must meet applicable local reasonable use standards and criteria. It is unlikely that middle housing
would be considered a reasonable use compared to a single-family residence in general, especially if the
middle housing proposal would have more impact on the critical area. For more information, see the
Commerce Critical Areas Handbook.
96 "Critical Areas Handbook." Department of Commerce. https://deptofcommerce.app.box.com/s/rlys4rfvrxpxwnm9bvbcd3lc7bil9ntp
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3.7 — Subdivisions
General subdivision considerations are noted below. See also the discussion of unit lot subdivisions in User
Guide Chapter 4.2.
Subdivision Alterations
Generally, when any person is interested in the alteration of an existing subdivision a subdivision alteration
may be required pursuant to RCW 58.17.215. However, a city may provide an exception to the subdivision
alteration process for middle housing unit lot subdivisions under RCW 36.70A.635(5) if the unit lots created: 1,
do not amend existing conditions of approval of previously platted property; 2) would not result in the violation
of a condition on the face of the plat; and 3) would not result in the violation of a covenant of the plat.
Otherwise, a new subdivision would be required.
When a subdivision alteration is required, the statute provides options which could make the process easier to
work through. A subdivision alteration application only requires the signature of a majority of those persons
having an ownership interest of lots, tracts, parcels, sites, or divisions in the subject subdivision or portion to
be altered. If the alteration only impacts a portion of the lots within a subdivision versus a proposal to remove
an easement impacting all properties, for example, then only the majority of property owners within the area
altered should need to sign the subdivision alteration application.
The statute also allows making a hearing on the subdivision alteration optional. While notice of the alteration is
required to be sent to all property owners in a subdivision, a hearing is only required if requested within 14 days
of receipt of the notice.
Alleys
Under the provisions of RCW 36.70A.635(6)(b), alleys cannot be required for middle housing subdivisions if
they are not also required for single-family subdivisions.
Alleys are useful for the configuration of middle housing because they allow vehicle parking, services, and
utilities to be collected in the rear of a development and create a more walkable streetscape in front of the lot.
Alleys are particularly helpful for increasing the design flexibility of narrow lots. Cities can consider requiring
new subdivisions, including unit lot subdivisions, to include alley -access lots, but this should be balanced with
physical and economic considerations. Alleys require more land or shallower lots than a subdivision without
alleys. Alleys may also add infrastructure costs for development. On a neighborhood or citywide scale, alleys
may have limited benefits if new alleys are not part of a continuous alley network outside of the subdivision.
One option is to only require alleys in new subdivisions over a certain size for economy of scale (e.g., 10 acres)
and/or if alleys are part of the existing street network in the vicinity.
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4.0 - Integration with Other State Law Requirements
4.1 — HB 1337 and Accessory Dwelling Units
HB 1337, codified in part under RCW 36.70A.681(1)(c), requires cities and counties to allow at least two
accessory dwelling units (ADUs) on all lots that are located in all zoning districts within an urban growth area
that allow for single-family homes.
For middle housing, RCW 36.70A.635(5) states, in part:
"...A city may allow accessory dwelling units to achieve the unit density required in subsection (1) of this
section. "
Cities may allow ADUs to count towards unit density to help achieve density requirements. The key word "may"
indicates that counting ADUs toward middle housing unit density is voluntary. The Model Ordinances do not
predetermine whether a city will or will not count ADU's towards unit density under RCW 36.70A.635(5). Cities
that choose not to count ADUs towards unit
density should allow at least two ADUs per lot on
all lots that are located in all zoning districts
within an urban growth area that allow for single-
family homes, as long as they comply with other
regulations for ADU development.
Cities that choose to count ADUs towards units
density should carefully review RCW
36.70A.635(5) which states, in part,
(5) A city must allow at least six of the nine
types of middle housing.... A city may
allow accessory dwelling units to achieve
the unit density required in subsection (1)
of this section. Cities are not required to
allow accessory dwelling units or middle
housing types beyond the density
requirements in subsection (1) of this
section...."
Configurations allowed if City counts
ADUs towards HB 1110 unit density
Unit
Unit ADU
Unit Unit
Additional configurations allowed if
city does not count ADUs towards
unit density
LEI ADU
ADU
Unit ADU
ADU
Unit
ADU
Configurations allowed in the Model Ordinances where the base unit
density is two units on lots zoned predominantly for residential use.
Source: MAKERS
Since cities are not required to allow ADUs beyond the minimum unit density requirements for their tier, a
scenario could present itself where at least two ADU's would not be allowed. For example, a Tier 1 city that
allows up to four units per lot, and counts ADU's towards unit density, could allow a triplex and an ADU to
achieve the four units per lot. As RCW 36.70A.635 states that a city is not required to allow accessory dwelling
units beyond the four unit density requirement, then depending on the city's code a second ADU might not be
allowed on the lot.
As this represents a conflict between the requirements of the accessory dwelling unit legislation passed in
2023 (HB 1337) with HB 1110's unit density provisions, it is recommended that cities consult with their city
attorney on this issue when drafting middle housing development regulations.
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ADUs do not count as a middle housing type and, therefore, do not count towards the requirement of allowing
six of nine middle housing types or four of nine middle housing types for Tier 3 cities.
Cities choosing to count accessory dwelling units as part of "unit density" and adopting the term in local code
can consider updating the definition to include accessory units. See unit density definition in Model Ordinance
Section 3. Also refer to the Department of Commerce ADU Guidebook.
4.2 - SB 5258 and Unit Lot Subdivisions
Senate Bill 5258 (2023), codified in RCW 58.17.060(3), requires:
All cities, towns, and counties shall include in their short plat regulations procedures for unit lot subdivisions
allowing division of a parent lot into separately owned unit lots. Portions of the parent lot not subdivided for
individual unit lots shall be owned in common by the owners of the individual unit lots, or by a homeowners'
association comprised of the owners of the individual unit lots.
Jurisdictions must implement this requirement by their next periodic comprehensive plan update.
This chapter provides model unit lot subdivision standards with provisions commonly used by Washington
cities that allow and regulate unit lot subdivisions. Unit lot subdivisions are almost exclusively used in
conjunction with middle housing.
The model unit lot subdivision standards below should be supplemented with approval findings, which may or
may not be similar to required findings for short subdivision or subdivision. Jurisdictions may also with to
amend their local project review requirement to specify submittal materials for unit lot subdivision permit
applications, should they differ from short subdivision or subdivision requirements.
Model Unit Lot Subdivision Standards
X. Unit lot subdivisions. A lot may be divided into separately owned unit lots and common areas, provided the
following standards are met.97
Process. Unit lot subdivisions shall follow the application, review, and approval procedures for a short
subdivision or subdivision, depending on the number of lots.
2. Applicability. A lot to be developed with middle housing or multiple detached single-family residences, in
which no dwelling units are stacked on another dwelling unit or other use, may be subdivided into
individual unit lots as provided herein.
3. Development as a whole on the parent lot, rather than individual unit lots, shall comply with applicable
unit density and dimensional standards.
4. Subsequent platting actions and additions or modifications to structure(s) may not create or increase any
nonconformity of the parent lot.
5. Access easements, joint use and maintenance agreements, and covenants, conditions and restrictions
(CC&Rs) identifying the rights and responsibilities of property owners and/or the homeowners'
97 RCW 58.17.060(3)
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association shall be executed for use and maintenance of common garage, parking, and vehicle access
areas; bike parking; solid waste collection areas; underground utilities; common open space; shared
interior walls; exterior building facades and roofs; and other similar features shall be recorded with the
county auditor.
6. Within the parent lot, required parking for a dwelling unit maybe provided on a different unit lot than the
lot with the dwelling unit for which the parking serves, as long as the right to use the parking is included in
notes on the face of the plat or short plat or formalized by an easement recorded with the county auditor.
7. Portions of the parent lot not subdivided for individual unit lots shall be owned in common by the owners
of the individual unit lots, or by a homeowners' association comprised of the owners of the individual unit
lots. 9s
8. Notes shall be placed on the face of the plat or short plat as recorded with the county auditor to state the
following:
a. The title of the plat shall include the phrase "Unit Lot Subdivision."
b. Approval of the development on each unit lot was granted by the review of the development, as a
whole, on the parent lot.
Effect of Preliminary Approval. Preliminary approval constitutes authorization for the applicant to develop
the required facilities and improvements, upon review and approval of construction drawings by the
public works department. All development shall be subject to any conditions imposed by the city on the
preliminary approval.
10. Revision and Expiration. Unit lot subdivisions follow the revision and expiration procedures for a short
subdivision.
11. Definitions.
a. "Lot, parent" means a lot which is subdivided into unit lots through the unit lot subdivision process.
b. "Lot, unit" means a subdivided lot, that allows up to one dwelling unit, created from a parent lot and
approved through the unit lot subdivision process.
c. "Unit lot subdivision" means the division of a parent lot into two or more unit lots within a
development and approved through the unit lot subdivision process.
98 The owner of a detached single-family residence may propose developing middle housing on their lot while retaining ownership of
the existing residence using unit lot subdivision. When the subdivision occurs, the existing residence must be placed on its own unit lot.
This is because the unit lots are each regular sellable lots with their own parcel identification number. Alternatively, if the existing
residence is being converted to a non-residential use, standard (A)(7) may apply so it is owned in common.
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Local Policy Choice
Short Subdivisions
RCW 36.70A.635(5) states, in part: ... A city must also allow zero lot line short subdivision where the number of
lots created is equal to the unit density required in subsection (1) of this section. As Tier 1 cities must allow up
to six units per lot, then they must allow at least six lots to be created in through a short subdivision process.
Under RCW 58.17.020(6), a "short subdivision" is the division or redivision of land into four or fewer lots, tracts,
parcels, sites, or divisions for the purpose of sale, lease, or transfer of ownership. However, RCW 58.17.020(6)
states that the legislative authority of any city or town may by local ordinance increase the number of lots,
tracts, or parcels to be regulated as short subdivisions to a maximum of nine.99 At a minimum, however, Tier 1
cities who limit short subdivisions to four lots need to raise the number to six lots.
All cities and towns interested in streamlining the subdivision process and promoting middle housing should
set the maximum number of lots, tracts or parcels that can be created in a short subdivision to nine, as
authorized by RCW 58.17.020(6) and encouraged by RCW 36.70A.600(1)(k). Short subdivisions require an
administrative process and are typically reviewed and approved on a faster timeline than a subdivision.
Administrative Review of Preliminary and Final Plats
RCW 36.70A.600(1) encourages cities to:
• Adopt standards for administrative approval of final plats pursuant to RCW 58.17.100
• Adopt ordinances authorizing administrative review of preliminary plats pursuant to RCW 58.17.095
Discussion
About Unit Lot Subdivisions
Unit lot subdivisions are almost exclusively used in conjunction with middle housing. This type of subdivision
uses the same procedures for a short plat or plat, depending on the number of unit lots being created. The unit
lots created by this type of subdivision are regular sellable lots with their own parcel identification number but
enjoy relaxed application of dimensional standards for the zone. The below graphic shows two conceptual unit
lot subdivision plats and how unit lots and the parent lot interact with setback standards.
Parent Lot
Unit Lot
Owned in Common
Parent Lot Setbacks
----------------
or
Cottag
Unit
Ixi
OF,off
=t Unit Unit
5
V104
r—Ott tage Cottage Cottage
Street Street
Two examples of situations in which unit lot subdivision would be used. Source: MAKERS
99 This authority was established in 2002 by SB 5832.
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Any type of dwelling unit which is stacked above another dwelling unit or other use cannot be part of a unit lot
subdivision. This restriction is because individual lots are created with individual land ownership, and so each
unit must have its entire footprint on the land associated with it. Stacked flats and other forms of middle
housing with units separated by floors are therefore ineligible for a unit lot subdivision. Multiplex
configurations where an upper -floor unit has an entry on the ground floor but the majority of the unit is on an s
upper -floor are also ineligible for a unit lot subdivision. 2
Unit Density in Unit Lot Subdivisions
The unit density standards apply to all existing and future lots in relevant zones. New middle housing
development must conform to zoning, including density limits. Once a middle housing development has been
constructed, the unit lot subdivision can be used to create new lots that are non -conforming with zoning
regulations such as minimum lot size, setbacks, coverage, and/or FAR. Because the new unit lots are in non-
conformance with zoning, no new development may be permitted on the unit lots. Units up to the unit density
limit (two, four, or six) are allowed on each unit lot, but since it is impossible to further develop the unit lot,
functionally no additional density may be added.
Minimum lot size: 7,000 SF Short Subdivision Unit Lot Subdivision
Lot area: 15,000 SF Lot area: 7,500 SF each Unit lots: 1,875 SF each
Development is No further development is
permitted on each lot permitted due to non-conformance
Zero Lot Line
The term "zero lot line" is used in several times in RCW 36.70A.635. State law does not define "zero lot line" nor
"zero lot line subdivision."
Cities should interpret "zero lot line" to mean the physical state of a building located, or permitted to be
located, on one or more property lines on a lot. This state can be achieved where a zoning setback requirement
is zero feet, within an attached townhouse developments on individual lots are allowed, or through other code
mechanisms. This can also be achieved development in a unit lot subdivision; subsection (A)(3) in the example
text helps cities comply with RCW 36.70A.635(5).
References
Examples of unit lot subdivision standards adopted by Washington cities:
• Snohomish Municipal Code 14.215.125
• Shoreline Municipal Code 20.30.410(B)(4)
• Wenatchee Municipal Code 11.32.080
• Everett Municipal Code 19.27
Citv of Alaona — Unit Lot Subdivision Freauentiv Asked Questions and TiDs (Short
City of Bellevue — Unit Lot Subdivision Project Page and Code Amendments
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4.3 — HB 1220 and Housing Elements
In 2021, the Washington Legislature changed the way communities are required to plan for housing. House Bill
1220 (2021) amended the Growth Management Act (GMA) housing goal to guide local governments to "plan
for and accommodate" housing affordable to all income levels. This significantly strengthened the previous
housing goal, which was to "encourage" affordable housing.
HB 1220, codified in RCW 36.70A.O20(4). RCW 36.7OA.03O, RCW 36.70A.O70(2), RCW 36.70A.390, RCW
35A.21.43O, and RCW 35.22.683 includes direction to the Department of Commerce to provide existing and
projected housing needs for communities in Washington, including units for moderate, low, very low and
extremely low-income households, and for emergency housing, emergency shelters and permanent supportive
housing.
Emergency housing/shelters I NA
Extremely Low I 0-30% AMI, including some permanent
supportive housing
Very Low 1 >30-50%
Low 1 >50-80%
Moderate 1 >80-120%
Other I Above 120%
Affordability levels defined in RCW 36.70A.030
Some, but not all, middle housing types allowed under RCW 36.70A.635 can help meet housing needs for
moderate income households in the 80-12O% Area Median Income (AMI) band required under RCW
36.70A.070(2). While there is a wide range of housing affordability outcomes that could be possible through
middle housing development given the diverse market conditions across Washington, there are some middle
housing types that have been found to be affordable for households in the 80-120% AMI band.100 Those types
are:
• Fourplexes
• Fiveplexes
• Sixplexes
• Townhouses
• Stacked flats
• Courtyard apartments
• Cottage housing
too This has been documented through technical support materials developed by the Department of Commerce as well as analysis
conducted by some individual cities.
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Additional review to verify this finding at the local level is recommended, such as through a housing needs
assessment created for a comprehensive plan or housing action plan.101 Allowing for greater housing choices
within areas that have historically excluded by race will also assist in meeting housing element goals to
address past practices and policies that have contributed to racially disparate impacts and exclusion.)oz
While these middle housing types could be built to meet the need for moderate -income housing, development
standards that physically allow and encourage these housing types are required to actually see that housing
development occur at income levels that cities and counties are planning for.
Development standards including parking requirements, square footage allowances, density allowances,
minimum lot sizes, and other dimensional standards need to be adopted. Additionally, fee structures and
review procedures need to encourage these housing types over other less dense and more expensive housing
types, such as detached single-family residences.
In Kitsap, King, Pierce and Snohomish Counties, cities can use a pro -forma tool developed by Cascadia
Partners in coordination with the Department of Commerce to evaluate how middle housing outcomes could
be accounted for using regulatory inputs customized by each city.103 A jurisdiction can enter information about
the density, height, setback, parking and other restrictions of a zone, in combination with land values, and
determine what income level housing in that zone could serve. More details on this tool are available on
Commerce's middle housing webpage under "Middle Housing Resources.""'
If a city were to conduct its own analysis regarding the combined effectiveness of affordability requirements,
density bonuses, and other regulatory and financial incentives a city may determine that it could reasonably
count a share of housing built under HB 1110 in the low income (50-80%) AMI income bracket. If there is a
precedent in a jurisdiction for affordable housing density bonuses to yield affordable housing, or a comparable
jurisdiction with a similar housing market yields such housing, a jurisdiction may use this information to
assume a small percentage of new units might develop in the <80% AMI income bracket.105
101 See the Department of Commerce guidebook for developing a housing needs assessment.
102 See the Department of Commerce guidance on addressing racially disparate impacts.
103 Pro -forma tool for PSRC region: https://deptofcommerce.box.com/s/csph6h612vbr47yovggxtszdd5s7w03g90
104 https://www.commerce.wa.gov/serving-communities/growth-management/growth-management-topics/planning-for-middle-
housin
101 https://deptofcommerce.app.box.com/s/1 d9d517g509r389fOm6powh8is4pirlh (page 35)
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4.4 — Land Use Elements and Land Capacity
Overview
Development feasibility analysis of middle housing types in communities across Washington indicates that
there is a wide range of potential development outcomes that could be reasonable to expect over a 20-year
planning horizon. Development outcomes, and an understanding of potential development capacity, from
middle housing allowances can vary greatly depending on macro -economic conditions as well as local market
conditions such as achievable pricing and demand, as well as land availability for vacant, infill, and
redevelopment sites.
These analyses conducted across cities in Washington have estimated that a range of three to 15 percent of
parcels across a city could reasonably be expected to develop or redevelop as middle housing over a 20-year
planning horizon.106 Analysis conducted by the Puget Sound Regional Council on the development and
redevelopment impacts of HB 1110 estimated that approximately 9% of parcels in Puget Sound Tier 1, Tier 2,
and Tier 3 cities could be expected to develop or redevelop over a 20-30 year time period in their mid -high
development scenario.107
Additionally, analysis of middle housing development feasibility on greenfield sites in cities with high demand
for housing indicates that nearly 50% of housing types built as part of larger planned development projects
could likely be middle housing types with the remaining 50% built as traditional detached single -dwelling units.
In conversations with developers there are a variety of reasons why middle housing could make up a large
share of overall housing types built on greenfield sites. Middle housing allows developers to capture a broader
range of market segments, housing can be offered at lower price points that have more demand when feasible,
and it allows developers to increase the overall sales volume and productivity of development on greenfield
sites.101
Not all sites that are zoned for middle housing will develop or redevelop as middle housing. In addition to sites
needing appropriate zoning for development, middle housing also needs to be physically and financially
feasible, there needs to be builders who are familiar with building middle housing, sites need to be for sale or
have property owner interest in selling, market timing must be appropriate, and there must be sufficient
demand for middle housing types in these locations.
106 "Housing Action Plan Implementation." City of Auburn, presentation to Planning Commission, January 4, 2023.
https://webl i nk. auburnwa.gov/External/DocView.aspx?id=485625&dbid=0&repo=CityofAuburn
107 TSSBHB1110: Development & Redevelopment Impacts." Puget Sound Regional Council. https://www.psrc.org/media/7556
108 "2040 Urban Growth Management Decision: Middle Housing Potential." Oregon Metro, MTAC Presentation, May 2023.
https://www.oregonmetro.gov/sites/default/files/metro-events/MTAC-meeti ng-packet-May-17-2023-fi nal. pdf
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Physical & Financial
Feasibility
Property for Sale / Property
Owner Interest
Viable Sites Available for Infill /
Redevelopment
Market Timing, Other Ways to Add
Value to Site, Market Depth / Demand
Infill /
Redevelopment
Occurs
Source: ECONorthwest
The land capacity analysis process. Source: ECONorthwest
Considerations for Land Capacity Analysis
The Department of Commerce has recently developed guidance for cities who are updating their Housing
Elements as part of their Comprehensive Plan Updates and has identified high-level guidance for how cities
can approach thinking about land capacity analysis specific to HB1110 requirements.'09
When considering land capacity under HB1110, cities should consider:
1. Which lots would be potentially redevelopable (i.e., those without homeowner association restrictions,
those that are vacant or have only one dwelling unit, those with a developable area over 2,000 square feet,
etc.).
2. Of the lots in Step 1, determine which subset of lots may economically make sense to redevelop. A starting
point for this analysis could be where to the land value is greater than the improvement value and the built
square footage is less than 1,400 square feet.
3. Estimate the total development potential of lots selected through Step 2, i.e., the maximum number of
dwelling units allowed to be developed on these lots net of existing units. Then determine what percentage
of the development potential (or net maximum dwelling units) could reasonably be expected to redevelop
over the 20-year planning period.
It is also helpful to remember that assumed densities, justifications for assumed densities, and potential
development outcomes for middle housing will be different than those that have been observed for detached
single dwelling development, multifamily development, and mixed -use development. Cities can reference the
anticipated development outcomes identified at the beginning of this chapter (a three to 15 percent parcel
redevelopment rate) as comparison points to understand how local market dynamics might impact
development outcomes in their own jurisdictions. In identifying assumed development rates for land capacity
analysis, cities should incorporate information about local market conditions and real estate market dynamics.
101 "Guidance for Updating Your Housing Element." Department of Commerce.
https://deptof commerce. a pp. box.com/s/1 d9d5l7g509r389fOmjpowh8isjpirlh
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Lessons Learned from Other States
Oregon's Administrative Rules (OAR) for implementation of House Bill (HB) 2001 can provide some guidance
on how other states have considered middle housing development and land capacity analyses. The OAR
identifies a maximum of 3% increase in the number of dwelling units produced due to middle housing
allowances within the specified residential zone(s), above the baseline estimate of land capacity prior to
allowing middle housing types within a 20-year planning horizon.
However, Oregon jurisdictions can conduct their own analyses to make a case for a higher share of dwelling
units that could reasonably be delivered. Oregon's approach takes a conservative path to account for
development capacity while putting the burden of proof on cities to demonstrate why an increased middle
housing development rate is warranted.
Some communities in Oregon did opt to conduct analyses to better understand how they can reasonably
account for new middle housing allowances required under HB 2001. For example, Washington County found
that, on average, 3% of parcels are feasible for development across all urban unincorporated areas but that the
rates of development feasibility ranged from less than 1 % in some neighborhoods to more than 6% in other
neighborhoods. Analysis conducted in Milwaukie, Oregon estimated that 8% of parcels are feasible for
redevelopment while 14% of parcels may have feasible infill potential on vacant portions of sites when an
existing house was retained.
Future Land Use Designations and Policies
Cities' comprehensive plan land use elements often have policies and land use designations based on unit -per -
acre densities. Such unit -per -acre density numbers may be incompatible with the measure of "unit density" per
lot introduced by RCW 36.70A.635, as "unit density" does not consider lot size and land area. Cities subject to
RCW 36.70A.635 will need to consider how their land use element uses "density" to describe future residential
land use designations.
For example, if a Tier 3 City currently describes a single-family land use designation as having a maximum
density of five units per acre, such language is now contrary to the provisions of RCW 36.70A.635. Since Tier 3
and Tier 2 cities are subject to a base unit density of two units per lot, the overall density on an approximately
8,700 square foot lot could double and be up to ten units per acre.
Additionally, with the middle housing requirements of HB 1110, some cities are rethinking the naming
conventions for residential land use designations and zones. While cities are not required to remove "single
family" from the names of future land use designations and zones, some cities have already chosen this route
to avoid the strict single-family connotations. For example, the City of Walla Walla has renamed its previous
"single family" zones as "Neighborhood Residential" zones" which allow both detached and middle housing
types. Other cities are simply using the terms like "Residential Low" and "Residential High" which allow more
flexibility to adjust the mix of housing types.
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4.5 - SB 5058, SB 5258, and Condominium Buildings
Effective July 23, 2023, the definition of a "multiunit residential building" in Washington's condominium
construction defect disputes law now exempts buildings with 12 or fewer units and with two stories or less.
See RCW 64.55.010(6). This ends requirements for developers of such buildings to:
• Submit a building enclosure design document to the building authority before obtaining a building permit.
• Obtain a building enclosure inspection by a qualified building inspector during construction or rehabilitative
construction.
Obtain a building enclosure inspection by a qualified building inspector before conveyance of a
condominium unit.
These requirements for condominium buildings can add time and expense to the development of
condominium units, as compared to middle housing or multifamily buildings with rental units which do not
have these requirements. SB 5058 may have the effect of encouraging the development of 2-12 unit
condominium buildings, including middle housing buildings, and therefore increasing homeownership
opportunities.
Senate Bill 5258 also revised condominium law to accelerate the timelines for the right -to -cure process when
claims are made for construction defects and requires a written report from a qualified construction defect
professional. The bill also exempts condominium and townhouse sales to first-time homebuyers from the real
estate excise tax. See RCW 64.50.030(1) through (3) and RCW 82.45.240.
To leverage these bills, cities and counties could consider where there are opportunities to allow up to twelve
units per lot and provide other incentives for condominium and townhouse development.
4.6 - SB 5235 and "Family" Definition
Effective July 25, 2021, cities and towns may not limit household occupancy based on the number of unrelated
persons. This may affect the definition of "family" and related terms like "single family" and "multifamily" in
local development regulations.
RCW 35.21.682 was added by Senate Bill 5235 with this provision:
"Except for occupant limits on group living arrangements regulated under state law or on short-term
rentals as defined in RCW 64.37.010 and any lawful limits on occupant load per square foot or generally
applicable health and safety provisions as established by applicable building code or city ordinance, a
code city may not regulate or limit the number of unrelated persons that may occupy a household or
dwelling unit."
Cities may limit allowed occupant load per square foot for health and safety reasons. Refer to the state
building code and any local building code amendments."'
110 WAC 51-50-1004
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4.7 — SB 5258 and Impact Fees
Senate Bill 5258 (2023) requires local jurisdictions which apply impact fees to adopt a fee schedule that
reflects the proportionate impact of new smaller housing units based on the number of trips generated (for y
transportation impact fees only), the square footage of a dwelling unit, or the number of bedrooms in a
dwelling unit. See RCW 82.02.060(1). Under RCW 82.02.060(10), jurisdictions must comply with these
requirements within six months after the jurisdiction's next periodic comprehensive plan update required under
RCW 36.70A.130.
Also note that RCW 36.70A.681(1)(a) requires impact fees for accessory dwelling units to not be greater than
50% of the fees that would be charged for the principal unit on the lot (typically a single-family home).
More information on impact fees is available from the Municipal Research and Services Center (MRSC).11'
Local jurisdictions in Washington may impose impact fees for one or more of the following:
• Public streets and roads.
• Publicly owned parks, open space, and recreation facilities.
• School facilities.
• Fire protection facilities.
Middle housing dwelling units are generally smaller than new detached single-family residences. Many cities
vary impact fees by the size or type of the unit and exempt certain types of single-family residences from some
or all impacts fees when they are trying to promote that housing type. In some cases, impact fee schedules
make no distinctions for middle housing types and by default they may be classified as single-family, therefore
incurring higher costs and a disincentive to their development. As noted above, fee structures which
accommodate middle housing can help make middle housing more economically feasible to develop.
Cities and counties updating impact fees which may affect non -city service providers (e.g., school districts)
should coordinate with those service providers on impact fee schedules and capital facilities plans.
"I "Impact Fees." Municipal Research Service Center. https://mrsc.orci/explore-topics/planning/land-use-administration/impact-fees
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The table below shows a general example of park impact fees imposed on different housing unit types and
options a city might take to implement for adjustment under RCW 82.02.060(1).
Single-family home, 2,500 $4,000
square feet, four bedrooms I ($1.60/SF) $5,875 $4,400
Townhouse unit, 1,500 square $4,000
feet, three bedrooms I ($2.66/SF) $3,525 $3,300
Fourplex unit, 1,100 square $2,500
feet, two bedrooms I ($2.27/SF) $2,585 $2,200
Apartment unit, 900 square $2,500
feet, two bedrooms ($2.77/SF) $2,115 $2,200
Example of park impact fees adjusted per RCW 82.02.060(1)
4.8 - Shoreline Master Programs and Regulations
An environmental stakeholder focus group noted that shoreline management and water access are an equity
issue with residential shorelines tending to be developed with exclusive higher -cost housing. Shoreline master
programs (SMP) are a "development regulation" subject to RCW 36.70A.635(6)(b). This is provided by the
definition of "development regulations" under RCW 36.70A.030 and RCW 36.7OA.48O(1) which reads in part:
All other portions of the shoreline master program for a county or city adopted under chapter 90.58 RCW,
including use regulations, shall be considered a part of the county or city's development regulations.
RCW 36.70A.635(6)(c) states that development permit and environmental review processes related to
shoreline regulations under chapter 90.58 RCW are not required to be the same as for detached single-family
residences. While RCW 36.70A.635(6)(c) addresses processes, to comply with RCW 36.70A.635(6)(b), cities
cannot adopt local policies that result in different land use allowances, shoreline setbacks, and other
standards for middle housing which actively or effectively prohibit the development of middle housing in
shoreline environments and meeting the density, parking, and other standards of RCW 36.70A.635.
However, jurisdictions may still use local discretion to regulate middle housing differently on other issues to
protect shoreline ecological function to the extent permitted by Chapter 90.58 RCW and associated rules under
Chapter 173-26 WAC. For example, middle housing may require different types of shoreline development
permits than detached single-family residences. Chapter 90.58 RCW, Chapter 173-26 WAC, and Ecology -
approved local shoreline master programs may restrict development under the goals, policies, purpose, and
intent of the Shoreline Master Program.
Each SMP contains residential use regulations and development standards which ensure that allowed uses
and development remain compatible with the shoreline environment and SMP and allow no net loss of
shoreline ecological function. Middle housing still would need to meet SMP critical area, impervious surface,
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and vegetation conservation provisions. Within shoreline jurisdiction, zoning code provisions can be applied,
but they must be reviewed in addition to the bulk, dimensional, performance, and use standards of the SMP. All
new development and uses, including middle housing, can only be authorized through the shoreline permitting
system outlined in Chapter 173-27 WAC.
Local governments should plan for middle housing within shoreline jurisdiction during a periodic review of their
SMP. Review and update of an SMP is required every ten years but can be initiated by a local government
outside of the required schedule. Local governments wanting to address middle housing under the authorities
of their SMP should consult Washington State Department of Ecology guidance and work closely with their
Ecology shoreline planner.112,113,114
References
• Department of Ecology — Shoreline Planners Toolbox
• Department of Ecology — Shoreline Master Programs Handbook
112 Department of Ecology — Shoreline planning and permitting staff. https://ecology.wa.gov/Water-Shorelines/Shoreline-coastal-
management/Shoreline-coastal-planning/Contacts
113 Department of Ecology — Shoreline Master Programs. https://ecology.wa.gov/Water-Shorelines/Shoreline-coastal-
management/Shoreline-coastal-planning/Shoreline-Master-Programs
114 "Shoreline Management Act." Municipal Research Service Center. https://mrsc.org/explore-topics/environment/environmental-
laws/shoreline-management-act
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5.0 - Affordable Housing
The housing affordability requirements of RCW 36.70A.635 are included in Section 5 of the Model Ordinance.
The requirements apply to Tier 1 and 2 cities, and they function as a unit per lot density increase as described
in the table below.
Tier 1 14 units per lot 1 6 units per lot, at least 2 of which must be affordable housing
Tier 2 12 units per lot 14 units per lot, at least 1 of which must be affordable
Affordability requirements of RCW 36.70A.635
What qualifies as "affordable housing" is defined in the Growth Management Act (GMA) under RCW
36.70A.030(5). Affordable housing means units that have costs, including utilities other than telephone, that do
not exceed 30 percent of the monthly income of a household whose income does not exceed the following
percentages of median household income (MHI) adjusted for household size, for the county where the
household is located, as reported by the United States Department of Housing and Urban Development:
Rental housing: 60 percent MHI
Owner -occupied housing: 80 percent MHI
For affordable owner -occupied housing, cities should clearly define affordable sales prices by bedroom size.
Sales prices should use a budget -based approach that considers the same factors used by a mortgage lender
to qualify a borrower. The budget -based approach includes other monthly housing costs like property taxes,
insurance, and homeowner association or condominium owner association fees.
For affordable rental housing, if a city has an existing methodology for determining rental housing affordability
it should apply that program. Alternatively, cities should refer to the U.S. Department of Housing and Urban
Development methodology for determining rental limits.
5.1 - Development Feasibility Analysis
Development feasibility analysis conducted in support of this User Guide indicates that affordability
requirements in RCW 36.70A.635 could lead to affordable housing development in some markets. The analysis
included Tier 1 and Tier 2 cities across the state and used the pro forma assumptions listed in Appendix A -
Middle Housing Pro Forma Assumptions. Depending on local market conditions, the affordable housing
requirements may work well in some Washington cities and less well in others.
The analysis was conducted using a residual land value (RLV), or sometimes referred to as land budget
approach, which models the budget a developer would have available to purchase land after accounting for all
other predicted costs and revenues. If the land budget is equal to or greater than land costs in the area of a
project, the proposed development is likely feasible. If the land budget is zero, the development would only be
feasible if the land were provided for free or with an equivalent subsidy. If the land budget is negative, the
developer would require an additional subsidy to make the proposed development financially feasible.
This feasibility analysis found that in most markets across Washington, affordable ownership is the most
feasible and subsequently, the affordability provisions are most likely to occur for ownership. Layering other
affordable housing programs such as a Multifamily Tax Exemption (MFTE) program could potentially increase
development value, particularly for rental housing. However, MFTE programs need to be administered within
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defined residential target areas authorized under RCW 84.14.040 and cities should carefully consider program
affordability, set asides, and program lengths to ensure compliance across multiple programs authorized
under RCW 36.70A.540. P
Tier 1 Cities
The Tier 1 analysis included these housing prototypes:
• Market rate fourplex (rental)
• Sixplex with two affordable units (rental)
• Market rate four -pack townhouse (ownership)
• Six-pack townhouse with two affordable units (ownership)
The initial analysis with lower floor area ratio (FAR) limits (up to 1.0 FAR for six units) found that the affordable
requirements and bonus for Tier 1 cities in western and eastern Washington is accretive, meaning there is
value in the additional units that exceeds the cost of the affordability requirements. However, development
feasibility for affordable homeownership was found to be very challenging in high -cost markets, and affordable
rentals were found to not be feasible.
The analysis was rerun after the FAR limits were updated in response to the 30-day public comment period (up
to 1.6 FAR for six units).15 With the FAR limits included in the final Model Ordinance, feasibility improved. The
key findings are:
The market rate fourplex, market rate four -pack townhome, and six-pack townhome with affordable unit
prototypes are likely feasible under current market conditions in Tier 1 cities.
The market rate four -pack townhome is more feasible than the six-pack townhome with affordable units in
both eastern and western Washington Tier 1 cities.
Sixplex rental developments with two affordable units are likely not feasible in the Tier 1 cities evaluated.
There is no feasibility incentive for a traditional market rate developer to pursue a six -unit building with
affordable units over a four -unit all market rate. However, additional FAR would allow a non-profit developer
to still compete for land and build larger family -sized units.
Summary Affordability Analysis Results — Tier 1 Cities
$200
$150
$100
$50
$(50) $(23)
$(46)
$(100)
$182
Fourplex (Market) Sixplex (2 4-Pack Townhome 6-Pack Townhome
Affordable) (Market) (2 Affordable)
■Tier1- Western Washington Tier 1- Eastern Washington
Source: ECOnorthwest 2023.
115 Draft Tier 1 and 2 Cities Middle Housing Model Ordinance (November 6, 2023):
https://deptofcommerce.app.box.com/s/ennzxeh6e52imp5u1 tv3ngs4pvn76pwr
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Tier 2 Cities
The Tier 2 analysis included these housing protypes:
• Market rate duplex (rental)
• Fourplex with one affordable unit (rental)
• Market rate duplex (ownership)
• Four -pack townhouse with one affordable unit (ownership)
The initial analysis with lower FAR limits (0.8 for four units) found there is likely no incentive for a market rate
builder to choose to build affordable homeownership or rental units because of market conditions.
The analysis was rerun after the FAR limits were updated in response to the 30-day public comment period
(1.2 for four units).16 With the FAR limits included in the final Model Ordinance, the key findings are:
Duplexes for rent are marginally feasible and fourplexes for rent (with one affordable unit) are just slightly
not feasible given current market conditions in the Tier 2 city evaluated. However, there is a relatively small
feasibility gap between the duplex for rent and fourplex for rent (with one affordable unit); this could
indicate that if the rental markets strengthened in Tier 2 cities, a market rate builder could reasonably see
similar levels of return for both prototypes.
Both ownership duplexes and four -pack townhomes (with one affordable unit) are likely feasible in Tier 2
cities. However, because market rate duplexes are more feasible than the four -pack townhomes with one
affordable unit, market rate developers do not necessarily have an incentive to build denser under current
market conditions.
Summary Affordability Analysis Results — Tier 2 Cities
$60
$56
a)
$38
`O
$40
Q aD
in
$20
$3
a
'O
$(2)
0
$(2 0)
.0,Q
Duplex (For Rent,
Fourplex(1
Duplex (For Sale,
4-Pack Townhome (1
C
Market)
Affordable)
Market)
Affordable)
m
J
■ Tier 2 - Tri Cities
Source. ECOnorthwest 2023.
116 Draft Tier 1 and 2 Cities Middle Housing Model Ordinance (November 6, 2023):
https://deptofcommerce.app.box.com/s/ennzxeh6e52imp5u1 tv3ngs4pvn76pwr
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Considerations for Affordable Housing Program Implementation
Administering Affordable Home Ownership Programs with HB 1110
Administering an affordable homeownership program is generally more complex than managing an affordable
rental program. Cities need to establish a mechanism for preserving affordability when homeowners decide to
sell their properties. These resale restrictions can be administratively complex and require ongoing monitoring
and enforcement. The potential for property appreciation in homeownership programs can also create
complexities related to how appreciation is managed and shared between the homeowner and the program, as
it can affect long-term affordability goals.
Homeownership also comes with ongoing expenses such as property taxes, homeowners' insurance,
maintenance, and repairs. These costs can be unpredictable and add complexity for program administrators
and homeowners, especially if homeowners are not adequately prepared for these financial responsibilities.
To administer and manage an affordable homeownership program, cities have a few options:
• Cities can comply with HB 1110 requirements by developing and administering its own program for
monitoring and administrating its affordable homeownership program. This approach is likely to have
significant ongoing staff and administration costs for cities that do not have a current affordable housing
program or do not have capacity to manage a new program.
• Cities can pay a third party to monitor and audit its affordable homeownership program. Enforcement of
non-compliance is still required by city staff.
• Cities can engage with a regional partner to manage and monitor the program, such as South King Housing
and Homelessness Partners (SKHHP) or A Regional Coalition for Housing (ARCH).
• Cities can engage with a local housing authority to manage and monitor the program. Examples at the city
and county level include Spokane Housing Authority, Renton Housing Authority, Housing Kitsap, and
Housing Authority of Snohomish County."'
• The city can engage with a community land trust (CLT) or other nonprofit to manage the program. In the
CLT model, a nonprofit organization acquires and holds land specifically for the purpose of creating and
maintaining affordable homes. Homebuyers can purchase the houses built on the CLT-owned land but do
not own the land itself. Instead, they enter into long-term, renewable land leases, which keeps the cost of
homeownership lower.
As a best practice, cities should conduct regular annual audits to ensure compliance with affordability
requirements. In particular, cities will need to ensure that all income certifications were completed and valid at
the point of sale. Cities have a few options for enforcing compliance with program affordability requirements:
• Ensure the city has a deed restriction on file with the title of any affordable for -sale parcel.
• The city could put a lien on the property title equivalent to the lost affordability value; fees collected from
liens could either go into an affordable housing fund or create a revolving enforcement and auditing fund.
• The city could combine affordable units in a development under one affordability contract such that if one
unit lost its affordable status all affordable units in the property would convert to market rate, which would
incentivize all property owners in the development to enforce income certification and other requirements.
>» "PHA Contact Information." United States Department of Housing and Urban Development. A list of public housing authorities in
Washington: https://www.hud.gov/sites/dfiles/PIH/documents/PHA_Contact_Report_WA.pdf
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Administering Affordable Rental Programs with HB 1110
Many cities across Washington currently regulate compliance for affordable rental housing programs through
various programs that are authorized under RCW 36.70A.540. These programs might include inclusionary
zoning programs, MFTE programs, or other regulatory or process incentive programs to encourage affordable
housing. For cities that do have existing affordable housing compliance processes and programs,
administration of the HB 1110 affordability requirements for rental housing could be a relatively low burden.
However, if Tier 1 and Tier 2 cities do not have an existing affordable housing program, the same options for
compliance and administration exist as for homeownership programs. These options include:
• Developing and administering a city -managed program for monitoring and administrating its affordable
rental housing program. For cities that do not have an existing affordable housing rental program, this
approach is likely to have significant ongoing staff and administration costs. For cities that have an
existing affordable housing program under RCW 36.70A.540, this is the most straightforward option.
• The city can pay a third party to monitor and audit its affordable rental housing program. Enforcement of
non-compliance is still required by city staff.
• Cities can engage with a regional partner to manage and monitor the program, such as SKHHP or ARCH.
• Cities can engage with a local housing authority to manage and monitor the program. Examples at the city
and county level include Spokane Housing Authority, Renton Housing Authority, Housing Kitsap, and
Housing Authority of Snohomish County.
• The city can engage with a nonprofit or third -party provider to administer and manage the program.
Tools to Encourage Affordable Housing Development
Cities should consider a variety of other ways to increase housing affordability that could be implemented in
coordination with RCW 36.70A.635. Examples of strategies to promote affordable housing:
• Reduce or eliminate off-street parking requirements
• Increase State Environmental Policy Act (SEPA) threshold exemptions, adopt a SEPA infill exemption,
and/or adopt a SEPA planned action
• Expedite the permit and subdivision process
• Adopt a multifamily tax exemption program
• Waive or reduce development review and utility connection fees
• Fund affordable housing with local taxes and/or levies
• Identify surplus land available for affordable housing development
References
• Middle Housing in Washington. Technical Committee #4 Meeting. October 24, 2023.
• City of Tacoma — Draft Home in Tacoma Phase 2 FeasibilitvAnalvsis. Plannina Commission Presentation
October 18, 2023.
• Department of Commerce — Middle Housing and Attainability in the Puget Sound Region
• Department of Commerce — Planning for Housing in Washington
• Department of Commerce — Guidance for Updating Your Housing Element
• Department of Commerce — Guidance for Developing a Housing Action Plan
• Department of Commerce — Guidance for Developing a Housing Needs Assessment
• AARP — Discovering and Developing Middle Housing. October 2023.
• South King County Housing and Homelessness Partnership — King County Regional Housing Action Plan.
2020.
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5.2 - Alternatives to HB 1110 Affordability Requirements
Local Affordable Housing Programs
Cities may adopt additional affordable housing incentives that are part of other affordable housing programs
under RCW 36.70A.540. For cities that already have adopted affordable housing incentive program(s) under
RCW 36.70A.540, the terms of that program govern to the extent they vary.
Under an RCW 36.70A.540 program, affordability requirements for rental units cannot exceed 80 percent area
median income (AMI), and for ownership units cannot exceed 100 percent AMI.
Cities will need to meet the set -aside (share of units affordable), depth of affordability (AMI levels by tenure),
and duration of affordability requirements identified in RCW 36.70A.635 but can layer additional process,
regulatory, or financial incentives that might be available and applicable through an existing adopted RCW
36.70A.540 program.
The key affordability requirements of RCW 36.70A.635 that must be met include:
• Tier 1 cities allow 6 units per lot when at least 2 units are affordable
• Tier 2 cities allow 4 units per lot when at least 1 unit is affordable
• Affordable rental housing available at or below 60 percent MHI
• Affordable owner -occupied housing available at or below 80 percent MHI
• 50-year duration of affordability for both affordable rental housing and affordable owner -occupied housing
Note that the 50-year affordability requirement that exists in RCW 36.70A.635(2)(a) is also present in RCW
36.70A.540 with the option to accept payment in -lieu of continuing affordability. The affordable housing
requirements of RCW 36.70A.635(3) do not preclude cities from requiring any development to provide
affordable housing, either on -site or through an in -lieu payment, nor limit the city's ability to expand such a
program or modify its requirements.
Cities may not allow a fee in -lieu option for middle housing development as an alternative to meeting the on -
site affordability requirements established by RCW 36.70A.635.
Affordable Housing on Religious Organization Owned Property
Under RCW 36.70A.545, cities must allow an increased density bonus for any affordable housing development
located on property owned or controlled by a religious organization. Affordable housing under RCW
36.70A.545 must be occupied exclusively by households earning 80 percent AMI or less and must keep
affordability requirement for at least 50 years.
Enacting a density bonus under RCW 36.70A.545 would not exempt cities from affordability requirements of
RCW 36.70A.635, but it would provide the opportunity for cities to adopt additional affordable housing
incentives that allow more middle housing units on religious organizations' property. Middle housing
development may be well suited to religious organizations with modest resources and/or those that are
located in low -intensity residential neighborhoods.
This type of density bonus oriented toward middle housing could include:
• Increasing the maximum building height limit to 40 feet
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Increasing the maximum floor area ratio limit to 1.8 and having no lot coverage standard
Reducing side setbacks to three feet and/or reducing front setbacks to between five and seven feet
Allowing at least 10 units per lot or have no maximum density (allowing as many units that can fit within
the building envelope)
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6.0 - Alternative Compliance
HB 1110 provides cities with three paths to compliance, summarized below. The following chapter includes a
more detailed description of each option.
1. Standard Density Requirements in RCW 36.70A.635(1)
2. Alternative to Density Requirements - RCW 36.70A.635(4). This alternative permits a city to implement
the unit per lot density requirements (required in RCW 36.70A.635(1)) for "at least" 75 percent of lots in
the city that are primarily dedicated to single-family detached housing units.
RCW 36.70A.635(4)(b) identifies those areas and lots where the unit per lot density requirements will
not apply. RCW 36.70A.635(4)(c) identifies areas which may not be included in the 25 percent unless
the area has been identified as an area at higher risk of displacement under RCW 36.70A.070(2)(g).
3. Alternative local action option - RCW 36.70A.636(3). This alternative permits a city to seek approval
from the Department of Commerce of alternative local actions "substantially similar" to the
requirements in RCW 36.70A.635(1). This option requires submittal and approval by the Department of
Commerce. When this process is utilized, actions taken by the city are not subject to administrative or
judicial appeal under the State Environmental Policy Act (SEPA).
Option 1
Standard Density Requirements in
RCW 36.70A.635(1)
41 Policy and code changes are subject to
appeal (SEPA and Growth Management
Hearings Board)
Option 2
Alternative to Density Requirements
in RCW 36.70A.635(4)
25% of lots for which the requirements of
subsection (1) are not implemented must
include areas meeting the requirements
of RCW 36.70A.635(4)(b)(i-iv) and
must not include areas outlined RCW
36.70A.635(4)(c) (i-i i i)
A city using this option may request
an extension of time for implementing
requirements for areas at risk of
displacement pursuant to RCW
36.70A.637. This option requires
Commerce certification.
A city may also request an extension for
a lack of infrastructure capacity pursuant
to RCW 36.70A.638. This option requires
Commerce certification.
Policy and code changes are subject to
appeal (SEPA and Growth Management
Hearings Board)
Option 3
Alternative Local Action option in
RCW 36.70A.636
Implement actions substantially similar
to the standard requirements in RCW
36.70A.635
Substantially similar actions include
those listed in RCW 36.70A.636(3)(b),(c)
and (d).
Local actions approved by Commerce
are exempt from SEPA and GMA appeal
but Commerce's final decision is
appealable to the Growth Management
Hearings Board
Commerce will develop a process for
cities to seek approval under this option
Cities must choose one of the three paths. Requirements are found in RCW 36.70A.635, 36.70A.636, 36.70A.637 and 36.70A.638
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6.1 — Alternative to Density Requirements
RCW 36.70A.635(4)
The "alternative to density requirements" approach provides an option for jurisdictions to allow middle housing
on certain lots primarily zoned for single-family detached housing units. The alternative requires that at least
75 percent of the "lots in the city that are primarily dedicated to single-family detached housing units" be
subject to the unit per lot requirements of RCW 36.70A.635(1).
"Lots in the city that are primarily dedicated to single-family detached housing units" is not defined in the
Growth Management Act (GMA). To identify these lots, it is recommended that those residential zoning
districts where the permitted density is primarily focused on single-family detached housing be included. This
would generally be zoning districts with permitted densities at ten dwelling units per acre or less. Even if
middle housing is permitted in these zones, lower density zones are those primarily dedicated to single-family
detached units. Once identified, these lots will be the basis for how the "at least" 75 percent of the lots is
determined.
Eligible Lots
This alternative requires identification of which lots must be included in the "at least" 75 percent of the lots and
the 25 percent or less of the lots that may be excluded from the unit per lot requirements of RCW
36.70A.635(1).
Except for areas identified at higher risk of displacement under RCW 36.70A.070(2)(g), lots that must be
included in the "at least" 75 percent include:
Any areas for which the exclusion would further racially disparate impacts or result in zoning with a
discriminatory effect;
Any areas within one-half mile walking distance of a major transit stop;
Any areas historically covered by a covenant or deed restriction excluding racial minorities from owning
property or living in the area, as known to the city at the time of each comprehensive plan update.
Jurisdictions should therefore review displacement risk work completed as part of its housing element update
to ensure this requirement under RCW 36.70A.636(c) is met.
The 25 percent or less of the lots to be excluded from the unit per lot requirements of RCW 36.70A.635(1)
must include but are not limited to:
Lots designated with critical areas or their buffers11
Any portion of a city within a one -mile radius of a commercial airport with at least 9,000,000 annual
enplanements19
Areas subject to sea level rise, increased flooding, susceptible to wildfires, or geological hazards over the
next 100 years120
118 This applies even if a city chooses to not apply the critical areas exemption (available under RCW 36.70A.635(8)(a)) to the
requirements of RCW 36.70A.635(1). See related discussion in User Guide Chapter 2.4. Lots with critical areas or their buffers that a
city allows to be developed with middle housing under the provisions of RCW 36.70A.635(1) cannot be counted in the minimum of 75
percent of lots that remain subject to RCW 36.70A.635(1).
119 This only applies to Seattle -Tacoma International Airport. Enplanement data is provided by the Federal Aviation Administration:
https://www.faa.gov/airportsiplanning_capacity/passenger_al Icargo_stats/passenger
120 See resource links below.
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Areas within the city for which the department has certified an extension of the implementation timelines
under RCW 36.70A.637 due to the risk of displacement; due to the risk of displacement
Areas within the city for which the department has certified an extension of the implementation timelines
under RCW 36.70A.638 due to a lack of infrastructure capacity; due to a lack of infrastructure capacity
Vacant lots meeting the criteria above can be included in the 25 percent or less category.
Since RCW 36.70A.635(4)(a) states the density requirement of RCW 36.70A.635(1) may be implemented for
"...at least 75 percent" of the lots primarily dedicated to single-family detached housing units, then cities that
cannot meet this "at least" 75 percent threshold cannot use this alternative.
Displacement Risk
Cities choosing the alternative to density requirements of RCW 36.70A.635(4) and considering requesting an
extension of timelines for areas at risk of displacement under RCW 36.70A.637 must complete the anti -
displacement analysis as required by RCW 36.70A.070(2).
In requesting an extension, the city must create and submit a plan identifying its anti -displacement policies.
The plan must identify when the policies will be implemented, which must be before their next implementation
progress report required by RCW 36.70A.130(9). The area (mapped) at risk of displacement for which the
extension is being requested, as determined by the anti -displacement analysis, will need to be provided.
Additional Commerce guidance on the certification process will be forthcoming.
Lack of Infrastructure Capacity
Extensions of implementation deadlines for areas due to lack of infrastructure capacity requires that the city
demonstrate a lack of capacity to accommodate the density required in RCW 36.70A.635 for one or more of
the following: water, sewer, stormwater, transportation infrastructure, including facilities and transit services,
or fire protection services.
Among other items, a jurisdiction will need to document the extent of the infrastructure capacity deficiency,
include one or more improvements within its capital facilities plan to adequately increase capacity or identify
the applicable special purpose district responsible for providing the infrastructure, if the infrastructure is
provided by a special purpose district. Additional applicable water system plan information is required for
timeline extension requests associated with lack of water supply to allow for Commerce evaluation of the
request.
RCW 36.70A.638 includes specific provisions related to water and sewer. These provisions can be interpreted
to be applicable not only to the time extension provisions of RCW 36.70A.638, but to middle housing in
general.
Water: RCW 36.70A.638(9) states that a city may limit the area subject to the requirements of RCW 36.70A.635
to match current water availability in the following circumstances, if the area is zoned predominantly for
residential use:
• The area is currently served only by private wells
• The area is served by a group A or group B water system with less than 50 connections 121, 122
121 Group A water systems information from the Washington Department of Health: https://doh.wa.gov/community-and-
environment/dri nki ng-water/water-system-assistance/tnc-water-systems
122 Group B water systems information from the Washington Department of Health: https://doh.wa.gov/community-and-
environment/dri nki ng-water/water-system-assistance/group-b
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A city or water provider(s) within the city do not have an adequate water supply or available connections to
serve the zoning increase required under RCW 36.70A.635
This does not, however, affect or modify the responsibilities of cities to plan for or provide urban governmental
services.
Sewer: RCW 36.70A.638(11) states that areas zoned predominantly for residential use currently served only by
on -site sewage systems may limit development to two units per lot on lots subject to RCW 36.70A.635, until
either the landowner or local government provides sewer service or demonstrates a sewer system will serve
the development at the time of construction. As with the case for water discussed in the preceding paragraph,
this does not affect or modify the responsibilities of cities to plan for or provide urban governmental services.
It is recommended that the code allow the number of units provided for in RCW 36.70A.635(1) but that a
supplemental standard, footnote, or other notation be provided stating that the absence of sewer service may
limit redevelopment until such time sewer infrastructure improvements are made.
Commerce has no general approval authority for the alternative to density requirements approach. However, if
a jurisdiction seeks an extension of timelines for certain areas at risk of displacement (RCW 36.70A.637) or for
areas lacking infrastructure capacity (RCW 36.70A.638), then Commerce certification of those time extensions
is first necessary before those areas may be included in the 25 percent.
Other items identified in RCW 36.70A.638 will be required to document the lack of infrastructure capacity. As
noted above, the process to document an infrastructure capacity deficiency could include providing maps,
capital facility plan information, and documentation from outside agencies regarding the current lack of
capacity. Processes to address the capital facility or utility planning requirements may be found at RCW
36.70A.070(3)-(4) and WAC 365-196-415 through WAC 365-196-420. Additional Commerce guidance on the
certification process is forthcoming.
For cities considering this option, it is important to remember that just because new middle housing types may
be allowed under RCW 36.70A.635 does not mean it can be built. For example, if an area lacks sewers
currently, middle housing units may not be permitted until such time adequate infrastructure is provided.
However, allowing middle housing uses could be a prompt for infrastructure improvements to be made by
developers over time. Not allowing redevelopment for middle housing could be a barrier to improvements
being made overtime.
Resources
Displacement risk
• Washington Department of Commerce — Draft Displacement Risk Map
• Puget Sound Regional Council — Displacement Risk Mapping
Racially disparate impacts and racially restrictive covenants
• Washington Department of Commerce — Guidance to Address Racially Disparate Impacts
• King County — Unlawful, discriminatory restrictive covenants
• University of Washington — Racial Restrictive Covenants
Infrastructure planning
• Washington Department of Commerce — Capital Facilities Planning
• Capital facility and utility planning requirements: RCW 36.70A.070(3)-(4) and WAC 365-196-415 through
WAC 365-196-420
Flood risk
• National Weather Service — Flooding in Washington
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• Washington Emergency Management Division - Flood Hazard Profile
• Federal Emergency Management Agency - Flood Maps
• First Street Foundation - Flood Factor
Sea level rise risk
• Washington Department of Ecology - Sea Level Rise
• Washington Coastal Network - Sea Level Rise Resources
• National Ocean Service - 2022 Sea Level Rise Technical Report
Wildfire risk
• First Street Foundation - Fire Factor
• U.S. Forest Service Pacific Northwest Research Station - A "New Normal" for West -Side Fire
• U.S. Forest Service - Wildfire Risk to Communities
• Federal Emergency Management Agency- Wildfire
Geological hazard risk
• Washington Department of Natural Resources - Geologic Hazard Maps
• Pacific Northwest Seismic Network - Liquefaction Hazard Maps
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6.2 - Alternative Local Action
This option is appropriate for jurisdictions which have taken actions by certain dates that are substantially
similar to the requirements of House Bill 1110. Where applicable to a city, this could reduce further legislative
action needed to comply with HB 1110.
Two alternative local action options, summarized as follows, are identified in RCW 36.70A.636. Both actions
require approval by Commerce to be in effect.
Alternative Local Action 1
A city has adopted comprehensive plan policies, by January 1, 2023, which are consistent with the provisions
of RCW 36.70A.635 and will take action to adopt permanent development regulations "substantially similar" to
the requirements of RCW 36.7OA.635 by July 23, 2024 (RCW 36.7OA.636(3)(b)). Actions deemed substantially
similar include those that:
Result in an overall increase in housing units allowed in single-family zones that is at least 75 percent of
the increase in housing units allowed in single-family zones if the specific provisions of RCW 36.70A.635
were adopted;
• Allow for middle housing throughout the city, rather than just in targeted locations; and
• Allow for additional density near major transit stops, and for projects that incorporate dedicated affordable
housing.
Alternative Local Action 2
A city has adopted comprehensive plan policies or development regulations, by January 1, 2023, that have
significantly reduced or eliminated residentially zoned areas that are predominantly single family (RCW
36.70A.636(3)(c)). A Commerce finding of "substantially similar" can be met if the city's permanent
development regulations are adopted by July 23, 2024 that:
Result in an overall increase in housing units allowed in single-family zones that is at least 75 percent of
the increase in housing units allowed in single-family zones if the specific provisions of RCW 36.70A.635
were adopted; and
Allow for middle housing throughout the city, rather than just in targeted locations; and
Allow for additional density near major transit stops, and for projects that incorporate dedicated affordable
housing.
Commerce "Substantially Similar" Determination
As part of the review process of Alternative Local Action 1 and Alternative Local Action 2 listed above, the
Department of Commerce may determine that the combined impact of the adopted comprehensive plan and
development regulations are substantially similar to the requirements of RCW 36.7OA.635 even if the city's
request does not demonstrate the criteria listed in RCW 36.70A.636 (3)(b) and (c) are met.
This determination is only possible when the Department of Commerce determines that the city has clearly
demonstrated that the adopted development regulations will allow for a greater increase in middle housing
production in single-family zones than would be allowed through implementation of RCW 36.70A.635. This will
require a capacity analysis prepared by the city comparing middle housing production between RCW
36.70A.635(1) and the city's plan/development regulations applicable to single-family zones.
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SEPA Safe Harbor
If a city choosing a local alternative action listed above is required to make a SEPA threshold determination for
that action, the action is exempt from administrative or judicial appeal.123 An action by Commerce to approve
or reject actions under the option are appealable to the Growth Management Hearings Board, however.
123 RCW 36.70A.636(3)(e)
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Appendix A - Middle Housing Pro Forma Assumptions
Prepared by ECONorthwest in January 2024.
Building Form
Tenure
Rental
Ownership
Rental
Ownership
Rental
Ownership
Units
2
2
4
4
6
6
Floors
2
2
2
3
3
3
Gross Residential
4,200 SF
4,200 SF
4,795 SF
5,250 SF
5,985 SF
6,000 SF
Area
Unit size
1,900 SF
1,900 SF
1,099 SF
11313 SF
998 SF
1,000 SF
Bedrooms
3-bed
3-bed
2-bed
2-bed
2-bed
2-bed
Monthly Market Rate Rent Revenue Assumptions
Market Rate
Tier 1 - Western Washington $3,069
$1,775
$1,450
Tier 1 - Eastern Washington
$2,565
$1,594
$1,347
Tier 2 - Tri Cities
$2,660
$1,829
$1,758
$1,430
$1,437
$1,430
Rents Affordable at 60% of MFI
Tier 1 - Western Washington
Tier 1 - Eastern Washington
$1,473
$1,153
$1,153
Tier 2 - Tri Cities
$1,640
$1,283
$1,283
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Sales Price Assumptions
1 Market Rate
Tier 1 - Western Washington $779,000
$478,225
$354,825
Tier 1 - Eastern Washington
$560,000
$376,030
$310,000
Tier 2 — Tri-Cities
$640,000
$400,290
$330,000
—
Sales Prices Affordable at 80%
of MFI
Tier 1 - Western Washington
$398,717
$355,518
$355,518
$287,973
Tier 1 - Eastern Washington
$269,596
$269,596
Tier 2 - Tri-Cities
$339,834
$309,833
$309,833
Hard Costs per Square Foot
Tier 1 - Western $185 $185 $196 $187 $194 $183
Washington
Tier 1 - Eastern $176 $176 $186 $177 $184 $174
Washington
Tier 2 - $181 $181 $192 $183 $190 $179
Tri-Cities
Other Cost Assumptions
Item
Vacancy costs, market rate units
Value
5%
Calculation Basis
Of rental revenues
Of rental revenues
Of rental revenues
Vacancy costs, affordable units
Operating costs, rental units
2%
20%
Commission cost from unit sales
3%
Of sales revenues
Surface parking stalls
$7,000
Per stall
Private garage parking
Soft Costs
Contingency
Developer Fee
Debt Service Coverage Ratio
$22,000
Per stall
Of hard costs
Of Hard + Soft Costs
25%
4.0%
5.0%
Of total development cost
135%
Of net rental revenues
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