Spears Yelm Engineering Letter flat (1)M u S Domus Structural Engineering, LLC
T H 11 C I- U R A 11 P.O. Box 560
Broomfield, CO 80038
C, T E N R T N G T, T, C 530-864-7055
projects@domusstruc.com
December 11, 2024
To: Blue Raven Solar
1403 North Research Way, Building J
Orem, UT. 84097
Subject: Certification Letter
Spears Residence
16452 Canal St
Yelm, WA. 98597
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) 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 27 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) 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 attachments 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 = 2021 IBC/IRC, ASCE 7-16
• Roof Dead Load = 7 psf (MP1&2)
• Roof Live Load = 20 psf
• Wind Speed = 110 mph (Vult), Exposure C
• Roof Snow Load = 25 psf
• Attachment: 2 - #14 Wood Screws with 1.75 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
IVAt
Digi igned
by John A. Calvert
Date: 2024.12.11
13:09:04-07'00'
Spears Yelm WA 1
o M u S Domus Structural Engineering, LLC
If, H TT C 'I l K A I. P.O. Box 560
Broomfield, CO 80038
. : N C"r T N E H TZ T iti G T, L C 530-864-7055
projects@domusstruc.com
Gravity Loading
Roof Snow Load Calculations
p9 = Ground Snow Load =
25.0 psf
pf = 0.7 Ce Ct I p9
(ASCE7 -
Eq 7-1)
Ce = Exposure Factor =
1
(ASCE7 -
Table 7-2)
Ct = Thermal Factor =
1
(ASCE7 -
Table 7-3)
1 = Importance Factor =
1
pf = Flat Roof Snow Load =
25.0 psf
ps = CSpf
(ASCE7 -
Eq 7-2)
Cs = Slope Factor =
1.00
ps = Sloped Roof Snow Load =
25.0 psf
PV Dead Load = 3 psf (Per Blue Raven Solar)
DL Adjusted to 27 Degree Slope
3.37 psf
PV System Weight
Weight of PV System (Per Blue Raven Solar)
3.0 psf
X Standoff Spacing =
4.00 ft
Y Standoff Spacing =
6.08 ft
Standoff Tributary Area =
24.33 sft
Point Loads of Standoffs
73 lb
Note: PV standoffs are staggered to ensure proper distribution of loadinc
Roof Live Load = 20 psf
Note: Roof live load is removed in area's covered by PV array.
Roof Dead Load (MP1&2)
Composition Shingle
4.00 psf
Roof Plywood
2.00 psf
2x4 Top Chords @ 24"o.c.
0.73 psf
Vaulted Ceiling
0.00 psf (Ceiling Not Vaulted)
Miscellaneous
0.27 psf
Total Roof DL (MP1&2)
7.0 psf
DL Adjusted to 27 Degree Slope
7.9 psf
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S TRUCTURAL
- : N c7 N EERi 6 t 1.0
Wind Calculations
Per ASCE 7-16 Components and Cladding
Input Variables
Wind Speed
110 mph
Exposure Category
C
Roof Shape
Gable Roof
Roof Slope
27 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 psf
Standoff Uplift Calculations -Portrait
Zone 1
Zone 2
Zone 3
Positive
Ya =
0.67
0.77
0.80
0.67
GCp =
-1.45
-2.41
-3.10
0.44
Uplift Pressure =
-23.1 psf
44.1 psf
-58.8 psf
7.1 psf
ASD Uplift Pressure =
-13.8 psf
-26.4 psf
-35.3 psf
9.6 psf
X Standoff Spacing =
4.00 ft
4.00 ft
2.67 ft
Y Standoff Spacing =
6.08 ft
3.04 ft
3.04 ft
Tributary Area =
24.33 sqft
12.17 sqft
8.11 sqft
Dead Load on attachment =
73 lb
37 lb
24 lb
Footing Uplift (0.6D+0.6W) _
-293lb
-300 lb
-272 lb
Standoff Uplift Calculations -Landscape
Zone 1
Zone 2
Zone 3
Positive
ya =
0.69
0.79
0.80
0.69
GCp =
-1.49
-2.48
-3.20
0.46
Uplift Pressure =
-24.4 psf
-46.6 psf
-60.8 psf
7.6 psf
ASD Uplift Pressure (0.6W)=
-14.7 psf
-28.0 psf
-36.5 psf
9.6 psf
X Standoff Spacing =
6.00 ft
6.00 ft
4.00 ft
Y Standoff Spacing =
3.50 ft
1.75 ft
1.75 ft
Tributary Area =
21.00 sqft
10.50 sqft
7.00 sqft
Dead Load on attachment =
63 lb
32 lb
21 lb
Footing Uplift (0.6D+0.6W) _
-270lb
-275 lb
-243 lb
Standoff Uplift Check
Maximum Design Uplift = -300 lb
Standoff Uplift Capacity = 400 lb
400 lb capacity > 300 lb demand Therefore, OK
Fastener Capacity Check
Fastener = 2 - #14 Wood Screws
Number of Fasteners = 2
Embedment Depth = 1.75 in.
Pullout Capacity Per Inch = 150 lb
Fastener Capacity = 525 lb
w/ F.S. of 1.5 & DOL of 1.6= 560 lb
560 lb capacity > 300 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)
Spears Yelm WA 3
o M u S Domus Structural Engineering, LLC
T R TT C 'I l R A I. P.O. Box 560
Broomfield, CO 80038
G T N E F R T iti G T, LC 530-864-7055
projects@domusstruc.com
Framing Check
(MP1 &2) PASS
w = 72 plf
Dead Load
7.9 psf
PV Load
3.4 psf
Snow Load
25.0 psf
2x4 Top Chords @ 24"o.c.
0
O
Governing Load Combo = DL + SL
Member Span = T- 0" \
Total Load
36.2 psf
Member Properties
Member Size
S (in^3)
I (in^4)
Lumber Sp/Gr Member Spacing
2x4
3.06
5.36
DF#2 @ 24"o.c.
Check Bending Stress
Fb (psi) = fb x Cd x Cf 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 = (wL12) / 8
= 443.735 ft#
= 5324.82 in#
Actual Bending Stress = (Maximum Moment) / S
= 1738.8 psi
Allowed > Actual -- 97.4% Stressed -- Therefore, OK
heck 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*L^4) / (185*E*I)
= 0.190 in
= L/443 > L/180 Therefore OK
Allowed Deflection (Live Load) = L/240
0.35 in
Actual Deflection (Live Load) = (w*L^4) / (185*E*I)
0.131 in
L/642 > L/240 Therefore OK
Check Shear
Member Area = 5.3 inA2 Fv (psi) = 180 psi (NDS Table 4A)
Allowed Shear = Fv * A = 945 lb Max Shear (V) = w * L / 2 = 254 lb
Allowed > Actual -- 26.9% Stressed -- Therefore, OK
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S:- T R TT C T l' K A I.
: : N G T l� 1 { R i iti G i. i. C
Lateral Check
Existina Weiaht of Effected Building
Domus Structural Engineering, LLC
P.O. Box 560
Broomfield, CO 80038
530-864-7055
projects@domusstruc.com
Level
Area
Weight (psf)
Weight (lb)
Roof
2517 sf
7.9 psf
19774 lb
Ceiling
2517 sf
6.0 psf
15102 lb
Wood Siding
100 ft
5.0 psf
2000 lb
Int. Walls
I 100 ft
1 6.4 psf
1 2560 lb
Existina Weiaht
of Effected Buildina 39436 lb
Proposed Weight of PV System
Weight of PV System (Per Blue Raven Solar) 3.0 psf
Approx. Area of Proposed PV System 362 sf
Approximate Total Weight of PV System 1086 lb
10% Comparison
10% of Existing Building Weight (Allowed) 3944 lb
Approximate Weight of PV System (Actual) 1086 lb
Percent Increase 2.8%
3944 lb > 1086 lb, Therefore OK
(8'-0" Wall Height)
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:E:-.N 'rINFFRTNG I.T. :
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 Domus 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, its 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 members 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 structure's 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.
Spears Yelm WA 6