BLD2023-1618_Structural_Calculations_12.18.2023_11.41.41_AM_3958247Domus Domus Structural Engineering, LLC
S TRUCTURA 1. P.O. Box560
Broomfield, CO 80038
N G T N E F. TZ ING I. T. C 530-864-7055
projects@domusstruc.com
December 18, 2023
To: Blue Raven Solar
1403 North Research Way, Building J
Orem, UT. 84097
Subject: Certification Letter
Goldengoose Residence
23729 80th Ct W
Edmonds, WA. 98026
To Whom It May Concern,
A jobsite observation of the condition of the existing framing system was performed by an audit team of Blue Raven Solar as a
request from Domus Structural Engineering. All review is based on these observations and the design criteria listed below and
only deemed valid if provided information is true and accurate.
On the above referenced project, the roof structural framing has been reviewed for additional loading due to the installation of
the solar PV addition to the roof. The structural review only applies to the section of the roof that is directly supporting the solar
PV system and its supporting elements. The observed roof framing is described below. If field conditions differ, contractor to
notify engineer prior to starting construction.
The roof structures of (MP1,2&3) consist of composition shingle on roof plywood that is supported by pre -manufactured trusses
that are spaced at @ 24"o.c.. The top chords, sloped at 18 degrees, are 2x4 sections, the bottom chords are 2x4 sections and the
web members are 2x4 sections. The truss members are connected by steel gusset plates. The max unsupported projected
horizontal top chord span is approximately 7'-0".
The existing roof framing systems of (MP1,2&3) are judged to be adequate to withstand the loading imposed by the installation
of the solar panels. No reinforcement is necessary.
The spacing of the solar standoffs should be kept at 72" o.c. for landscape and 48" o.c. for portrait orientation, with a staggered
pattern to ensure proper distribution of loads.
The scope of this report is strictly limited to an evaluation of the fastener attachment, underlying framing and supporting
structure only. The attachment's to the existing structure are required to be in a staggered pattern to ensure proper distribution
of loading. All panels, racking and hardware shall be installed per manufacturer specifications and within specified design
limitations. All waterproofing shall be provided by the manufacturer. Domus Structural Engineering assumes no responsibility
for misuse or improper installation of the solar PV panels or racking.
Design Criteria:
• Applicable Codes = 2018 IBC/IRC, ASCE 7-16
• Roof Dead Load = 7 psf (MP1,2&3)
• Roof Live Load = 20 psf
• Wind Speed = 110 mph (Vult), Exposure C
• Roof Snow Load = 25 psf
• Attachment: 1 - 5/16 dia. lag screw with 2.5 inch min. embedment
depth, at spacing shown above.
Please contact me with any further questions or concerns regarding this project.
Sincerely,
John Calvert, P.E.
Project Engineer
L�'P
p�41 t
ied by
John A. Calvert
Date: 2023.12.18
11:35:16-07'00'
Goldengoose Edmonds WA 1
Do m u s Domus Structural Engineering, LLC
T ft t7 C T l' E1Z A 1, P.O. Box 560
Broomfield, CO 80038
N Ci T N F E R T N G 1. 1. C 530-864-7055
projects@domusstruc.com
Gravity Loading
Roof Snow Load Calculations
pg = Ground Snow Load =
25.0 psf
pf=0.7CeCtlpg
(ASCE7 -
Eq 7-1)
C, = Exposure Factor =
1 (ASCE7 -
Table 7-2)
Ct = Thermal Factor =
1 (ASCE7 -
Table 7-3)
1 = Importance Factor =
1
pi = Flat Roof Snow Load =
25.0 psf
Ps = C Of
(ASCE7 -
Eq 7-2)
Cs = Slope Factor =
1
p, = Sloped Roof Snow Load =
25.0 psf
PV Dead Load = 3 psf (Per Blue Raven Solar)
DL Adjusted to 18 Degree Slope
3.15 psf
PV System Weight
Weight of PV System (Per Blue Raven Solar)
3.0 psf
X Standoff Spacing =
4.00 fl
Y Standoff Spacing =
6.08 fl
Standoff Tributary Area =
24.33 sft
Point Loads of Standoffs
73 lb
Note: PV standoffs are staggered to ensure proper distribution of loading
Roof Live Load = 20 psf
Note: Roof live load is removed in area's covered by PV array.
Roof Dead Load (MP1,2&3)
Composition Shingle
4.00
Roof Plywood
2.00
2x4 Top Chords @ 24"o.c.
0.73
Vaulted Ceiling
0.00 (Ceiling Not Vaulted)
Miscellaneous
0.27
Total Roof DL (MP1,2&3) 7.0 psf
DL Adjusted to 18 Degree Slope 7.4 psf
Goldengoose Edmonds WA 2
Do.mus
S TR1)CTI RA1,
E \G i NEE R I NG 1. LC
Wind Calculations
Per ASCE 7-16 Components and Cladding
Input Variables
Wind Speed
110 mph
Exposure Category
C
Roof Shape
Gable Roof
Roof Slope
18 degrees
Mean Roof Height
20 ft
Effective Wind Area
21.3 ft
Ground Elevation
0 ft
Design Wind Pressure Calculations
qh = 0.00256 * Kz * Kzt * Kd * Ke * V12
(Eq. 26.10-1)
Kz (Exposure Coefficient) = 0.90
(Table 30.3-1)
Kzt (topographic factor) = 1.00
(Fig. 26.8-1)
Kd (Wind Directionality Factor) = 0.85
(Table 26.6-1)
Ke (Ground Elevation Factor) = 1.00
V (Design Wind Speed) = 110 mph
(Fig. 26.5-1A)
Risk Category = II
(Table 1.5-1)
qh = 23.75
Standoff Uplift Calculations -Portrait
Zone 1
Zone 2
Zone 3
Positive
Y a =
0.67
0.77
0.80
0.67
GCp =
-1.82
-2.88
-3.60
0.44
Uplift Pressure =
-28.9 psf
-52.7 psf
-68.4 psf
7.1 psf
ASD Uplift Pressure =
-17.4 psf
-31.6 psf
-41.0 psf
9.6 psf
X Standoff Spacing =
4.00
4.00
2.67
Y Standoff Spacing =
6.08
3.04166667
3.04166667
Tributary Area =
24.33
12.17
8.11
Dead Load on attachment =
73 Ib
37 lb
24 Ib
Footing Uplift (0.6D+0.6W) _
-378 Ito
-363 lb
-318 Ito
Standoff Uplift Calculations -Landscape
Zone 1
Zone 2
Zone 3
Positive
ye =
0.69
0.79
0.80
0.69
GCp =
-1.95
-2.97
-3.60
0.46
Uplift Pressure =
-32.1 psf
-55.9 psf
-68.4 psf
7.6 psf
ASD Uplift Pressure (0.6W)=
-19.3 psf
-33.5 psf
-41.0 psf
9.6 psf
X Standoff Spacing =
6.00
6.00
4.00
Y Standoff Spacing =
3.50
1.75
1.75
Tributary Area =
21.00
10.50
7.00
Dead Load on attachment =
63.00
31.50
21.00
Footing Uplift (0.6D+0.6W) _
-367 lb
-333 lb
-275 lb
Standoff Uplift Check
Maximum Design Uplift = -378 lb
Standoff Uplift Capacity = 450 lb
450 lb capacity > 378 lb demand Therefore, OK
Fastener Capacity Check
Fastener = 1 - 5/16" dia. lag
Number of Fasteners = 1
Embedment Depth = 2.5
Pullout Capacity Per Inch = 250 lb
Fastener Capacity = 625 lb
w/ F.S. of 1.5 & DOL of 1.6= 667 lb
667.2 lb capacity > 378 lb demand Therefore, OK
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
(Fig. 30.3)
(Eq. 29.4-7)
(Fig. 30.3)
(Eq. 29.4-7)
Goldengoose Edmonds WA 3
Domu s
SLLTRUCTURAL
1. NG T N F E R T Nr i. i. (.
Dead Load 7.4 psi
PVLoad 3.2 psi
Snow Load 25.0 psi
Governing Load Combo = DL + SL
Total Load 36.5 p sf
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
Framing Check
(MP1,2&3)
w=71 plI
2x4 Top Chords @ 24"o.c.
O
Member Span = 7' - 0"
Member Properties
Member Size S (inA3) I (inA4) Lumber Sp/G r Member Spacing
2x4 3.06 5.36 DF#2 @ 24"o.c.
Check Bending Stress
Fb (psi) = fb x Cd x CI x Cr NDS Table 4.3.1)
900 x 1.15 x 1.5 x 1.15
Allowed Bending Stress = 1785.3 psi
Maximum Moment = (wLA2) / 8
= 435.0541 ft#
= 5220.649 in#
Actual Bending Stress = (Maximum Moment) / S
= 1704.8 psi
Allowed > Actual -- 95.5% Stressed -- Therefore, OK
Check Deflection
Allowed Deflection (Total Load) = L/180 (E = 1600000 psi Per NDS)
= 0.466 in
Deflection Criteria Based on = Continuous Span
Actual Deflection (Total Load) _ (w*LA4) / (185*E*I)
= 0.186 in
= L/452 > L/180 Therefore OK
Allowed Deflection (Live Load) = L/240
0.35 in
Actual Deflection (Live Load) _ (w*LA4) / (185*E*I)
0.131 in
L/642 > L/240 Therefore OK
Check Shea r
Member Area = 5.3 inA2 Fv (psi) = 180 psi (NDS Table 4A)
A Ilowed Shear = Fv * A = 945 lb Max Shear (V) = w * L / 2 = 249 lb
Allowed > Actual -- 26.4% Stressed -- Therefore, OK
Goldengoose Edmonds WA 4
DOMU S
S TRUCTURAL
E NC; T NEE R T NG L LC:
Lateral Check
Existina Weiaht of Effected Buildina
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
Level
Area
W eight (psf)
Weight (lb)
Roof
1573 sf
7.4 psf
11578 lb
Ceiling
1573 sf
6.0 psf
9438 lb
Wood Siding
100 ft
5.0 psf
2000 lb
Int. Walls
100 ft
1 6.4 psf
1 2560 lb
Existina Weiaht of Effected Buildina
25576 lb
Proposed Weight of PV System
Weight of PV System (Per Blue Raven Solar) 3.0 psf
Approx. Area of Proposed PV System 235 sf
Approximate Total Weight of PV System 705 lb
10% Comparison
10% of Existing Building Weight (Allowed) 2558 lb
Approximate Weight of PV System (Actual) 705 lb
Percentlncrease 2.8%
2558 lb > 705 lb, Therefore OK
(8'-0" Wall Height)
Goldengoose Edmonds WA 5
Domus
c3TTTRUCT` IRA 1,
1� X G T N E E R T N G T.T.0
Appendix A: General Notes
GENERAL
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
• The contractor shall verify all dimensions, property setbacks, AHJ/HOA CC&R's, elevations and site conditions before
starting work and shall notify Domus Structural Engineering, LLC of any discrepancies.
• All report conclusions represent Domus Structural Engineering, LLC's best professional judgment based upon industry
standards.
• Resolve any conflicts on the drawings with Domus Structural Engineering, LLC before proceeding with construction.
• The design criteria used for this project & listed on the first page of the report is based on the engineers best judgement
and/or provided by the ATC council. AHJ specific requests may differ. Please contact our team if the design criteria needs to
be modified.
• A site visit was not physically conducted by Domus Structural Engineering, LLC. The accompanying calculations and
certification are provided with the understanding that the site building and construction standards meet an acceptable level of
industry standards. It shall be the contractors responsibility to identify any irregularities such as inconsistent framing
conditions, water damage, fire damage, cracked, split or noticeably deflecting framing members.
• Domus Structural Engineering, LLC is not responsible for enforcing safety measures or regulations. The contractor shall
design, construct, and maintain all safety devices including shoring and bracing, and shall be solely responsible for
conforming to all local, state and federal safety and health standards, laws and regulations. The contractor shall take
necessary precautions to maintain and insure the integrity of the structure during construction. If a lawsuit is filed by one of
the contractor's or subcontractor's employees, or any one else, the contractor will indemnify, defend and hold the owner and
Domus Structural Engineering, LLC harmless of any and all such claims.
• Any and all waterproofing shall be provided by the contractor. Domus Structural Engineering, LLC is not responsible for
waterproofing.
• All hardware shall be installed per manufacturer specifications and within specified design limitations. Domus Structural
Engineering, LLC assumes no responsibility for incorrectly installed hardware or hardware installed outside of the
manfacturer specifications.
USER RELIANCE
Domus Structural Engineering, LLC was engaged by Blue Raven Solar (Client) to perform this assessment. This report and
the information therein, are for the exclusive use of the Client. This report has no other purpose and shall not be relied upon,
or used, by any other person or entity without the written consent of Dous Structural Engineering, LLC. Third parties that
obtain this report, or the information within shall have no rights of recourse or recovery against Domus Structural
Engineering, LLC, it's officers or employees.
ROOF MOUNTED ARRAYS
• If an analysis of a supporting stucture is included in our scope of work, the structural assessment only applies to the section
of the roof that is directly supporting the proposed solar PV system.
• No structural members can be cut for conduit, etc., unless specifically shown. Obtain prior written approval for installation of
any additional conduit, etc.
• It is assumed that a standard quality of construction care was used to construct the original building. It shall be the
contractors responsibility to field verify any and all framing member supporting the proposed PV array are in adequate
condition. The contractor shall field inspect for sub -standard construction means, signs of dry rot, mold, fire damage, etc. and
notify engineer if any compromised material is found on site prior to starting construction.
• It is assumed that there have been no additional loads (HVAC or MEP equipment, additional layers of roofing, etc) added to
the building over the course of the structures histroy. The contractor and/or client shall verify this with the property owner and
notify Domus Structural Engineering, LLC if additional load has been added to the structure already.
Flexible utility connections must be used at any building seismic joint.
• Care should be taken to ensure that PV arrays do not preclude drainage of rain water.
• Unless otherwise noted, construction material shall be evenly distributed if placed on framed floors or roofs. Loads shall not
exceed the allowable loading for the supporting members and their connections.
• All lags or wood screws at the roof shall be stainless steel and installed withing the middle 1/3 of the dimensional width of the
framing members.
• All fasteners shall be a minimum of 6" away from any truss panel or hinge joints, truss plates and/or member ends. Field
verify location of fasteners prior to starting construction. All fasteners shall be pre -drilled to avoid splitting existing lumber.
Domus Structural Engineering, LLC is not responsible for downslope effects of snow shedding or sliding off of the PV array
nor any damage to downslope decks, roofs, walkways, landscaping, automobiles, pets, people, etc.. If snow guards are
requested by the customer, notify Domus Structural Engineering, LLC.
Goldengoose Edmonds WA 6