Response letter.pdf1q)ff Comment Response
Date: July 6, 2018
To: Chuck Miller, Senior Plans Examiner, City of Edmonds
From: Thaddeus Egging, KPFF
Subject: Sherwood Elementary School Portable Classroom "B" (Permit # BLD2018-0471)
Comment Responses
The following comment responses are in response to Building Plan Review comments dated
June 26, 2018 prepared by Chuck Miller (attached for reference):
1. Thaddeus Egging, KPFF, and Will Thomsen, Edmonds School District, met with Chuck
Miller, City of Edmonds, on June 28, 2018 to discuss these comments. Per that
discussion the following changes have been made to address City of Edmonds
comments concerning location of Portable B in proximity to the adjacent existing
structures:
a. Portable B has been rotated 90 degrees within the courtyard to shift the doors
and associated ramps/stairways away from the adjacent buildings.
b. Portable B was previously considered as an extension of existing building Unit A.
This was in error. Sheet G0.0 has been revised to show Portable B as an
extension of existing building Unit C. Building occupancy (E) and construction
type (VB) for building Unit C is the same as that of A and the cumulative square
footage is below the limit of allowable area of 9,500 SF per IBC table 506.2
c. On sheet G1.0, the imaginary line has been drawn from the face of Unit A 10'-1".
This allows the face of Portable B to be 2'-4" from the imaginary line. This shift
also places the north edge of Portable B 10'-7" from the face of Unit C and the
mechanical access (also the north side) 8'-0" from the face of Unit C.
d. We have provided an elevation view of the north wall of existing building Unit A
demonstrating < 15% open area (SK01, attached to this response letter).
e. We have provided details of the wall section of existing building Unit A, excerpted
from the original 1966 drawing package, that show the wall section at Unit A to
be at least a 6-inch hollow block wall. Per IBC table 721.1(2) section 1-1.2 this
wall section to have a Prescriptive Fire Resistance of at least 1 hour.
f. The assembly of the proposed Portable B is similar to a UL V334 section which is
a 1-hr rated fire assembly. This is the most similar and equivalent wall system to
the portable.
The remaining comments from City of Edmonds in this package have been addressed by Briggs
Engineering. Their response letter is attached.
Attachments:
1. Sherwood Portable B Foundation Design Response Letter (by Dean Briggs)
2. Sherwood Portable B Comments by City of Edmonds
3. Sherwood Portable B Sketch 01: Unit A North Wall Elevation
4. Sherwood Portable B Sketch 02: Unit A Wall Section
5. Sherwood Portable B Foundation Calculations (by Briggs Engineering)
Attachment 1: Sherwood Portable B Foundation Response Ur
8.04-7 )
DEAN BRIGGS, PE
P.O. Box 140537, Garden City, ID 83714-0537
(208) 871-0200 / dean@briggs-engineering.com
Memorandum
To: Pacific Mobile, Mike Aldous
CC: File
From: Dean Briggs
Date: July 6, 2018
Re: 1804.09.1-3, BLD2018June 26th Comments, Chuck Miller
Oy-71
Mike:
Pursuant to the Second Structural Plan Review, June 26th we have addressed the comments as
requested by your office.
Following are our responses per the 6/26 Plan Review by Chuck Miller, City of Edmonds as
transmitted to BEI via Pacific Mobile Structures, Inc.:
1) Pacific Mobile Foundation Design & Sheet A20.1 (F1) Coordination:
• Calculations and corresponding notation on the plans address foundation sheathing. SDPWS-
2015, T4.3A, Note 2 allows 3/8", 7/16" and 15/32" sheathing to use the 15/32" lateral
resisting nominal values provided the shearwalls are blocked at a maximum spacing of 16"
o.c.. Attachments between the module rail and the 2x4 base plates have been clarified in the
calculations and on the foundation plan to no more than 4" o.c. in the area of the corner
shear blocks. Lateral resisting shear connections of the #12 Self -Tapping Screws at module
perimeter rail and 8d nails at P.T. 2x4 base plate are specified to be spaced at 4-inches on
center.
• Connection of module to perimeter plates in between the corner concrete shear blocks shear
blocks is not considered for shear transfer and does not need to be attached as such. A 12-
inch connector spacing is specified as a reasonable connection for general framing
requirements.
Site welding and epoxy anchorage has been eliminated from Sheet F1. Special Inspection
requirements for `Strong-Bolt-2' installation have been included in Foundation Notes as item
8. Edmonds School District will be required to complete the Special Inspection and Testing
Agreement for post installed anchors and have the special inspection completed per note 8,
as required by ESR-3037.
1801.09.1-3
Attachment 1: Sherwood Portable B Foundation Response Ur
July 6, 2018
2) Sheet A20.1 (F1) Detail 1:
a) Anchor strap width is shown as 3-inches in width on the plan and elevation.
b) Elevation View"
Calculations and corresponding notation on the plans address foundation sheathing. SDPWS-
2015, T4.3A, Note 2 allows 3/8", 7/16" and 15/32" sheathing to use the 15/32" lateral
resisting nominal values provided the shearwalls are blocked at a maximum spacing of 16"
o.c.. Attachments between the module rail and the 2x4 base plates have been clarified in the
calculations and on the foundation plan to no more than 4" o.c. in the area of the corner
shear blocks. Lateral resisting shear connections of the #12 Self -Tapping Screws at module
perimeter rail and 8d nails at P.T. 2x4 base plate are specified to be spaced at 4-inches on
center.
Connection of module to perimeter plates in between the corner concrete shear blocks shear
blocks is not considered for shear transfer and does not need to be attached as such. A 12-
inch connector spacing is specified as a reasonable connection for general framing
requirements.
3) Sheet A20.1 (F1) Detail 2 - Roof Column Support Pads:
• Detail 2 and Foundation Plan 'A' have been modified to include a 30" sq. footing, 12-inches
thick, to distribute the mateline roof beam column support load.
4) Sheet A20.1 (F1) Detail 3 — Exterior Wall Pad:
a) The double 2x4 supports have been replaced with multiple 2x4 bearing plates and are required
only if the modular building is on an uneven surface. The detail indicates the spacing of the
plates is a maximum of 48-inches o.c. and the plates cannot be more than 12-inches tall. The
calculations allow the spacing to be at 6.6-ft.
b) The 2x4 plates are not directly attached to the modular rim member. The exterior sheathing is
attached to both the 2x4 base plate and the module rim. The 2x4 bearing plates are attached to
the sheathing.
c) The double 2x4 supports have been replaced with multiple 2x4 bearing plates and are required
only if the modular building is on an uneven surface. The detail indicates the spacing of the
plates is a maximum of 48-inches o.c. and the plates cannot be more than 12-inches tall. The
calculations allow the spacing to be at 6.6-ft.
5) Sheet A20.1 (F1) Detail 4 — Mateline Pad:
• Detail 4 shows all requisite pads and blocking.
• All installation requirements are noted.
6) Sheet A20.1 (F1) Plan A — Foundation Plan:
a) Gridline 1-13, Foundation Plan 'A' have been modified to include a 30" sq. footing, 12-inches
thick, to distribute the mateline roof beam column support load. Noted as Detail 2.
b) Gridline 2-13, Foundation Plan 'A' have been modified to include a 30" sq. footing, 12-inches thick,
to distribute the mateline roof beam column support load. Noted as Detail 2.
1801.09.1-3 July 6, 2018 2
Attachment 1: Sherwood Portable B Foundation Response Ltr
July 6, 2018
7) Foundation Calculations II.B1:
a) Calculations have been modified to reflect tributary loads on exterior floor rim beam spans per
Blazer plans. Bearing pads have been adjusted accordingly on 'A/F1' &'1/F1' to 48" o.c.
b) Supplemental calculations are included to reflect the ability of the floor beams to span 15'10".
This is greater than the plan spacing of the bearing pads.
8) Foundation Calculations II.D:
• Calculations indicate the spacing required for a single 2x12-24" P.T. wood pad. That is
compared against the equivalent effective span of the mateline beam of 16-feet as shown. In
this instance the bearing is being provided by 'Alternative' concrete footing lieu of the
bearing pads which utilizes the base square footage.
• Notations for the concrete pad are included in the calculations and on 'A/F1'.
B> IM 9 27 2019
1801.09.1-3 July 6, 2018 3
Attachment 2: Sherwood Portable B Comments
City of Edmonds
PLAN REVIEW COMMENTS
BUILDING DIVISION
(425) 771-0220
DATE: June 26, 2018
TO: Will Thomsen
thomsenW(c-t,)edmonds.wednet.edu
FROM: Chuck Miller, Senior Plans Examiner
chLick. miIler ikdmondswa.
RE: Plan Check: BLD2018-0471 - 2nd review
Project Address: 22901 106th Avenue W
Project: ESD Sherwood Elementary relocatable classroom `B'
Scope: Siting, connection, support, and lateral restraint of manufactured classroom
structure - nonseparated Education Group E occupancy - 42 occupants - VB
construction - no sprinkler system - fire alarm under separate permit
Please be advised that the building plans for the above referenced project have been disapproved
for the purposes of obtaining a building permit. During a review of the plans by the Building
Division for compliance with the applicable building codes, it was found that the following
information, clarifications, or changes are needed. Reviews by other divisions, such as Planning,
Engineering, or Fire, may result in additional comments that require attention beyond the scope of
this letter. Items that recur on this list appear in italics.
A complete review cannot be performed until the revised plans/documents, including a
written response in itemized letter format indicating where the `clouded' or otherwise
highlighted changes can be found on the revised plans, have been submitted to a Permit
Coordinator. Only those sheets specifically referenced as follows need to be resubmitted.
Resubmittals must be made at the Development Services Department on the 2nd Floor of City Hall.
Permit Center hours are M, T, Th, & F from 8am-4:30pm and from 8:30am-12pm on Wednesdays.
On sheet G0.0 - Cover Sheet:
1. Site Plan - Locate on the plans between `Building Unit C' and the relocatable classroom the
`imaginary line' to be used to determine the exterior wall and opening protection set forth
in International Building Code (IBC) Sections 705.5 and 705.8 per IBC 705.3. The
response to the earlier plan review comment states: "Refer to revised sheet G1.0
(attached) for fire separation imaginary line (assumed property line) between Building
Unit C and relocatable classroom B. The fire separation/assumed property line is
drawn 10 feet from existing Building Unit C based on the following IBC requirements:
Attachment 2: Sherwood Portable B Comments
IBC 705.3 specifies "Where a new building is to be erected on the same lot as an
existing building, the location of the assumed imaginary line with relation to the
existing building wall shall be such that the exterior wall and opening protection of the
existing building meet the criteria a (sic) set forth in Section 705.5 and 705.8."
IBC 705.5 requires the fire resistance rating of the exterior walls to be rated for
exposure to fire from the inside if the fire separation distance is greater than 10 feet or
rated for exposure to fire from both side (sic) if the fire separation distance is less than
or equal to 10 feet. Conservative assumption that the existing Building C exterior wall
is rated for fire exposure from the inside requires the fire separation distance to be
greater than 10 feet.
IBC 705.8 allows a maximum area of exterior wall opening of 15% for an unprotected,
Nonsprinklered building with fire separation distance of 10 to less than 15 feet.
Building C exterior wall opening is approximately 14.95%, conforming to the
maximum wall opening area for the given fire separation distance.".
First, a `conservative assumption' regarding the fire -resistance rating of the exterior walls of
an existing structure of `Type VB' construction, located almost 60 feet from adjacent
structures, and not otherwise verified as such on approved building plans, would be that
none of the walls would be of fire -resistance rated construction. Second, on sheet `G1.0' the
resubmitted plans indicate that Building C is 10 feet from the `Assumed Property Line'.
Since 10 feet is not greater than 10 feet, the fire -resistance rating of the exterior walls must
be for exposure from both sides per IBC 705.5. Provide as part of a complete resubmittal
the design of a listed one -hour fire -resistance rated wall assembly tested for exposure from
both sides in accordance with ASTM El 19 or UL 263. Typically, a design with a
construction criteria (wall framing material, spacing of the wall framing, thickness of the
gypsum board, `type' of the gypsum board, placement and orientation of the gypsum board,
size of fasteners and their spacing, etc.) corresponding with that of the existing wall is
selected. Those portions of the `existing' wall construction to be retained as part of the fire -
resistance rated assembly must be represented on the plans will be verified by field
inspection.
An elevation representing the south exterior wall of Building C and the openings in the wall
for doors, windows, mechanical inlets/outlets, etc., and calculations supporting that the wall
openings total approximately 14.95 %, could not be found among the submitted construction
documents for verification of compliance with IBC 705.8.
The exterior wall and opening protection concerns regarding the placement of a new
building in close proximity to, and the potential effects upon, an existing building must also
be met for the new building — relocatable classroom B. The placement of the relocatable
classroom 5 feet from the `Assumed Property Line' would require the north exterior wall to
be of one -hour fire -resistance rated construction (with exposure from both sides) per IBC
Table 602 and limits the wall openings to 10% of the wall area per IBC Table 705.8. The
width of the ramp and the upper landing on the north side appear to extend beyond that
allowed for projections per IBC Table 705.2 and the placement of the stairs on the south side
does not comply with the required fire separation distance for exterior exit stairways/ramps
per IBC 1027.5 unless the wall and openings of Building A are protected per IBC 705.
Page 2 of 5
Attachment 2: Sherwood Portable B Comments
On sheet A20.1 — Pacific Mobile Foundation Designs:
2. Clarify on the plans the difference in the represented construction/connections and of that
specified in the provided structural calculations. Of particular concern are the lateral
design elements noted in Division 7F - Foundation Design — Section E' — Lateral Design —
of the calculations that to not appear on the plans. The response to the earlier plan review
comment states: "Differences between the submitted calculations page and foundation
drawing (A20.1) have been resolved. Revised sheet A20.1 and revised structural
calculations have been attached. Specific resolutions are highlighted and explanations
given in clouds. Note A highlights 7/16" sheathing prescribed by the calculations page
while thicker %" sheathing is described in the drawing. The note also points to the
calculations having 16" o.c. fastener spacing while the plans show 12" o.c. The thicker
sheathing and closer fastener should provide more strength and not be a problem.
Note B highlights 5/8" diameter anchor bolts and both the calculations and drawings
page. The drawing page gives options for 5/8" diameter anchor fasteners all satisfying
the requirements given by the calculations page.". The number of changes made to both
the various details represented on sheet `A20.1' and to the provided structural calculations
essentially makes the concerns noted in the earlier plan review comment irrelevant.
However, there are concerns regarding the assumptions noted in the response as follows:
a. The difference in the lateral design values between the attachment of the %2"
sheathing and of the 7/16" sheathing to the framing members is 2 pounds more per
fastener (or about 3%) per the National Design Specification for Wood Construction
(NDS). The benefit of the thicker sheathing would only be realized if the reduction
in the fastener spacing was less than 3%.
b. The calculations do not specify 16" o.c. fastener spacing. That is intended to be the
spacing between the (2)2x4 studs noted on pages 4 and 5 of the prior structural
calculations. The fastener spacing was specified to be 4" o.c.
The following additional plan review comments regard the resubmitted construction
documents as a `new review' due to both the changes made to the plans and to the structural
calculations (responses should be coordinated and incorporated onto the plans):
General plan review note:
The unique and specific nature of the work necessary to complete your project requires
special inspection per IBC 1704. A City of Edmonds `Special Inspection and Testing
Agreement' (see the end of these comments) for the following work will need to be
completed and returned prior to permit issuance:
• Site Welding
• Epoxy Adhesive Anchorage
On sheet A20.1 — Pacific Mobile Foundation Designs:
3. Detail 1 — Corner Pad and Anchors
a. Clarify on the plans the difference in the indicated width of the anchor strap on the
`elevation view' and of that specified on the `plan view'.
Page 3 of 5
Attachment 2: Sherwood Portable B Comments
b. Elevation View — Clarify on the plans the difference in the indicated spacing of the
fasteners into the wood framing members along wall lines `1' and `2' and of that
specified in Division `II' - Foundation Design — Section `E' — Lateral Design — Item
`2' — Lateral Walls (End, Short Walls) (page 4/4) - of the provided structural
calculations.
4. Detail 2 — Roof Column Support Pads - Indicate on the plans the minimum size of the
required isolated footing/support pads to support the loads below each end of the two 3-
1/2x21 24F-V4 GLB ridge beams. The total design load appears to be about 9300 pounds at
both gridline `1-13' and at gridline `2-13'.
5. Detail 3 — Exterior Wall Pad
a. Clarify on the plans the difference in the indicated spacing of the (2)2x4 studs and of
that specified in Division `II' - Foundation Design — Section `E' — Lateral Design —
Item `1' — Longitudinal Walls (Front and Back, Long Walls) — and — Item `2' —
Lateral Walls (End, Short Walls) (page 4/4) - of the provided structural calculations.
b. Clarify on the plans the indicated method of attaching the top of the (2)2x4 studs to
the module perimeter rail (HSS 8x2x3/16).
c. Clarify on the plans the resulting height of the (2)2x4 studs after considering the
height of floor above grade, the depth of the perimeter rail, and the preservative
treated 2x 12 and 2x4 bottom plates (and possible top plate). Studs may not be less
than 14 inches in length or solid blocking must be used per International Building
Code (IBC) 2308.5.6.
6. Detail 4 — Mateline Pad - Complete on the plans the provided information regarding the
placement of the 2x6 over the 12x24 `bearing pads'. A portion of the installation
requirements appears to be missing.
7. Plan A — Foundation Plan — 2802 Classroom
a. Clarify on the plans the `callout' to detail `4/F1' at gridline `1-B'. There does not
appear to be consideration given to the point load below the two 3-1/2x21 24F-V4
GLB ridge beams.
b. Clarify on the plans the `callout' to detail `2/F1' at gridline `2-13'. There does not
appear to be consideration given to the point load below the two 3-1/2x21 24F-V4
GLB ridge beams.
On the provided `Prefabricated Modular Building Pad Foundation Design' structural calculations
prepared by Briggs Engineering, Inc:
On sheet 3/4:
8. Division `II' -Foundation Design —Section `B1' — Exterior Pads (Exterior Rails) —Exterior
Uniform Load
a. Clarify on the provided information the extent of the tributary loads (L2a/12) from
the `RLL', `RDL', `CDL', and `EM' used to calculate the loads along wall lines `A'
and `C'. It does not appear to account for the placement of the ridgebeams in the
separate modules.
b. Clarify on the provided information the indicated `Max. span of Support Beams'.
Even using 50 ksi HSS 8x2x3/16, the perimeter rail appears to fail when spanning
more than about 14 feet when subjected to the loads noted above.
Page 4 of 5
Attachment 2: Sherwood Portable B Comments
9. Division `II' -Foundation Design —Section `D' — Column Pads (Roof Loads Only) —Clarify
on the provided information that regarding the `Effective Mateline Beam Span'. The two 3-
1/2x21 24F-V4 GLB ridge beams appear to span approximately 31.5 feet, without any
interior walls providing intermediate support.
Page 5 of 5