BSOL2020-0003 Structural Calcsvivint.��
Structural Group
J. Matthew Walsh, PE Kirk M. Nelson, SE
Director of Engineering Structural Engineering
james.walsh@vivintsolar.com kirk.nelson@vivintsolar.com
February 03, 2020
Re: Structural Engineering Services
Jacobs Residence
50485 Verano Dr, La Quinta, CA
S-6279294; CA-21
To Whom It May Concern:
1800 W Ashton Blvd.
Lehi, UT 84043
Samuel Brown, PE - Civil
Structural Engineering
sam.brown@vivintsolar.com
We have reviewed the following information regarding solar panel installation on the roof of the above referenced
home:
1. Site Visit by a representative from our office under my supervision identifying specific interior and
exterior site information including the condition of the existing roof system and the size, spacing, and
condition of existing structural framing members. Information gathered during the site visit includes
photographs, sketches, and verification forms.
2. Design drawings of the proposed PV System layout, including details to mount the new solar panels to
the existing roof.
Based on the above information, we have evaluated the structural capacity of the existing roof system to support the
additional loads imposed by the solar panels and have the following comments related to our review and evaluation:
According to the 2019 California Existing Building Code section 502.5 exception 1, if the weight of the panels does
not exceed 10% of the total weight of the building, changes to the building to address seismic/wind lateral forces are
not required. We have assumed the weight of the building to be 82968 Ibs and based on a panel weight of 1320 Ibs
the solar system would increase the total weight by only 1.6%. As such changes to the existing building to address
lateral forces are not required based on the current code.
A. Description of Residence: (!446
The existing residence has typical wood framing construction with the roofing. All wood material utilized for the roof
system is assumed to be Douglas Fir -Larch #2 or better with standard construction components. The designed
areas of the home consist of the following framing methods:
• Roof Sections: Prefabricated trusses at 24" on center. Survey photos indicate that there was free
access to verify the framing size and spacing. CTy O C i n �� �TA
B. Loading Criteria BUILDING DIVISION A �
16.02 PSF = Dead Load (roofing/framing) REVIEWED FOR
3.00 PSF = Dead Load (solar panels/mounting hardware) CODE
19.02 PSF = Total Dead Load CO PLIANCE
20 PSF = Roof Live Load (based on local requirements) DATE 20 BY
Wind speed of 130 mph (based on Exposure Category C - the total area subject to wind uplift is calculated for the
Interior, Edge, and Corner Zones of the dwelling.)
C. Solar Panel Anchorage
1. Installation shall proceed in accordance with the applicable guidelines and recommendations indicated below.
If, during solar panel installation, the roof framing members appear unstable or deflect non -uniformly, our office
should be notified before proceeding with the installation.
Page l of2 vivinte solar �-k
Page 2 of 2
• EcoFasten Solar Installation Manual, which can be found on the EcoFasten Solar website
(www.ecofastensolar.com).
2. The solar panels are 1'/z' thick. At no time will the panels be mounted higher than 10" above the existing
surface of the roof.
3. The following mounting types shall be used. Please refer to the mounting details for the associated required
penetration depth. Based on our evaluation, the pullout demand is less than the maximum allowable per
connection and therefore is adequate.
• EcoFasten Tile Mount: (2) 5/16" lag screw. Pullout capacity based on National Design Specifications
(NDS) of timber construction specifications for Douglas Fir -Larch is 235 Ibs/inch penetration.
4. Fasteners are installed to meet industry standards and this document satisfies requirements in 2019 CBC
2303.4.5 verifying that the fasteners will not adversely affect the roof framing.
5. The maximum allowed spacing was calculated for the Wind Speed shown in paragraph B above, using the wind
load uplift procedures of ASCE 7-16 and is specified below. These spacing requirements apply to all mount
types indicated above. The following values have been verified by in-house testing and the mounting hardware
manufacturers' data, which are available upon request. Panel support connections should be staggered, where
possible, to distribute load to adjacent members.
Modules in Lands cape
Modules in Portrait
Roof Zone
Interior
Ede
Corner
Interior
Ede
Corner
Max Vertical Spacing
40
40
40
66
66
66
Max Horizontal Spacing in
48
48
48
48
48
48
Max Uplift Load Ibs
411
466
264
411
466
264
D. Summary
Based on the above evaluation, with appropriate panel anchors being utilized the roof system designed on will
adequately support the additional loading imposed by the solar panels, if installed correctly. This evaluation has
been performed for the structural elements only and verifies that they are in conformance with the 2019 California
Building Code, current industry standards and practice, and the information supplied to us at the time of this report.
If there are any questions regarding the above, or if more information is required, please contact me.
Regards,
J. Matthew Walsh, PE
CA License No. C 73567
F��p�H�ly
C 73567
W Exp. '1 a 020
CI0-
vivi nt. solar
Structural Group
1800 IN Ashton Blvd.
Lehi, UT 84043
I Matthew Walsh, PE Kirk M. Nelson, SE Samuel Brown, PE - Civil
DkeetoroFEVneerft Strwtural Engineering Stradural Eroheertng
jame&walsh@vivintsolar.com kirk.nelson@vivintsolar.com sam.brown@vivintsolar.com
Structural Design Criteria
Project Address
Jacobs Residence
50485 Verano Dr
La Quinta, CA
S-6279294
Residence
Risk Category II
Roof Area 4280 sf
Upper Floor Area 0 sf
Number of Stories 1
Mean Roof height 15 ft
Upper Floor height 0 ft
Location Parameters
Latitude 33.68271
Longitude-116.26027
Site Class D
Risk Category II
Existing Gravity Parameters
Roof Dead Load
10 psf Tile
2 psf 3/4" Plywood Sheathing
1 psf Roof Framing @ 24 in. o.c.
2 psf Ceiling, Mechanical, Electrical
1 psf Miscellaneous
16 psf TOTAL
New Gravity Parameters
Date: February 3, 2020
Roof Live Load 20 psf Wall Dead Load
Ground Snow Load 0 psf 8 ft Wall Height
Flat Roof Snow Load 0 psf 300 ft Wall Length
12 psf Wall Weight
Roof Dead Load 3.00 psf Solar Panel Weight
Roof Live Load with Solar Panels 0 psf
Roof Slope Factor 0.8 Roof Slope Factor (ASCE 7-16 Fig. 7-2b)
Roof Snow Load 0 psf Asce 7-16 Eq. 7.4-1
Seismic Parameters
SS =
1.563 g
0.2 sec Spectral Response Acceleration
S1 =
0.642 g
1.0 sec Spectral Response Acceleration
Fa =
1.000 g
Site Coefficient from ASCE 7-16, Table 11.4-1
Fv =
1.700
Site Coefficient from ASCE 7-16, Table 11.4-2
SDS =
1.042 g
Short Period Design Spectral Acceleration
SD1 =
0.728 g
1 Second Period Design Spectral Acceleration
2/3/2020
Page 1 of 6 vivint. solar
Wind Parameters
Product Information
Wind Speed
130 mph
Exposure Category
C
Roof Angle, 0
23.0 deg
No. of Panels
25
Weight
3.00 psf including mounting system
Installed Area
439.6 1}2
No. of Connectors
45
Total Existing Roof Load = DLRooF+ (LLRooF or Snow) x Spacing
72.04 plf
Total New Roof Load = DLRooF+ DLADD + (LLRooF or Snow) x Spacing
38.04 plf
Change in Demand = (Total New Load - Existing Load) / Existing Load
-47.20%
Per 2019 CBC 1607.13.5.1, live load is not applied where solar panels are present. As such, loading of the
trusses is reduced with addition of PV.
Code References
2019 CRC Section AJ501.4 states:
"The minimum design loads for the structure shall be the loads applicable at the time the building was constructed, provided that a dangerous
condition is not created. Structural elements that are uncovered during the course of the alteration and that are found to be unsound or
dangerous shall be made to comply with the applicable requirements of this code."
Page 2 of 6 v'v' nt. s o l a r
Base Shear Calculations
2019 CBC
Site Class = D
Risk Category = II
SDs = 1.04
SDi = 0.73
Lateral force resisting system: Wood -Framed with Rated shear panels
RX = 6 1/2 from ASCE 7-16, Table 12.2-1
I = 1.0
No. Stories 1
h = 15.0 ft Mean Roof Height
Ct = 0.02 from ASCE 7-16, Table 12.8-2
x = 0.75 from ASCE 7-16, Table 12.8-2
TX = Cth„" = 0.152 sec Approximate Fundamental Period, ASCE 7-16, Equation 12.8-7
WFxfsTINc = 82.97 kip Approximate mass of building
WNFw = 84.29 kip Approximate mass of building and solar panels
Base Shear =
SDRx I W =
0.160 x W
ASCE 7-16, Equation 12.8-2
Max Base Shear =
SDl x I W =
0.734 x W
ASCE 7-16, Equation 12.8-3
TxR
Min Base Shear =
0.044 SDs x I (>_ 0.01) x W =
0.046 x W
ASCE 7-16, Equation 12.8-5
Min Base Shear =
0.5 xRSI x I W =
0.049 x W
ASCE 7-16, Equation 12.8-6
Cs = 0.160
Static Base Shear, Vx = 13.30 kip Existing
13.51 kip New
1.59% increase
INCREASE IS LESS THAN 10% - OK
Page 3 of 6 vivi nt. S o l a r
Vertical Distribution of Seismic Forces
2019 CBC
k = 1.00 Structural Period Exponent from ASCE 7-16 Section 12.8.3
Existing
V = 13.30 kip
Weight
Story Height,
k
wi hI
Diaphragm
Level (kip)
hi (ft)
w' h'
E(w; h•,k)
Force (kip) Story Force (kip)
Roof 82.97
15.0 ft
1245
1.000
13.30 13.30
2nd Floor 0.00
0
0
0.000
0.00 13.30
E
F 82.97
15.0 ft
1245
1.000
13.30
New
V = 13.51 kip
Weight
Story Height,
k
Wi h;k
Diaphragm
Level
w; h;
Story Force (kip)
(kip)
hi (ft)
k
E(wj h; )
Force (kip)
Roof 84.29
15.0 ft
1264
1.000
13.51 13.51
Upper 0.00
0
0
0.000
0.00 13.51
E
84.29
15.0 ft
1264
1.000
13.51
Demand Increases
Diaphragm Story Force
Level Force (kip) (kip)
Roof 1.59% 1.59%
Upper --
2019 CEBC Section 502.5 Exception 1 states:
INCREASE IS LESS THAN 10% - OK
"Any existing lateral load -carrying structural element whose demand -capacity ratio with the addition considered is no more than 10
percent greater than its demand -capacity ratio with the addition ignored shall be permitted to remain unaltered."
�i
Page 4 of 6 vivi nth u I a r
Wind Uplift
Rooftop Solar Panels Parallel to the Roof Surface on Buildings of All Heights and Roof Slopes
V = 130 mph Basic Wind Speed
Exposure C ASCE 7-16, Section 26.7
YE= 1 Middle of Array 1.5 Edge of Array Array Edge Factor ASCE 7-16 Figure 29.4-7
Ya= 0.75 Solar Panel Pressure Equalization Factor ASCE 7-16 Figure 29.4-8
KZ= 0.85 Velocity Pressure Exposure Coefficient ASCE 7-16 26.10.1
KZt= 1 Topographic Factor ASCE 7-16 26.8.2
Kd = 0.85 Wind Directionality Factor ASCE 7-16 Section 26.9
Ke = 1 Ground Elevation Factor Section 26.9
qh= 31.3 0.00256KZKZtKdK,V2 Velocity Pressure ASCE 7-16 26.10.2
Roof 0 = 23.0 deg
Sanchor = 48 in Horizontal spacing of roof anchors
Atrib = 21.60 sf Panel Area tributary to each roof anchor
p= (qh) (GCp)(YE)(Ya) Minimum Design Wind Pressure for Rooftop Solar Panels ASCE 7-16 Section 29.4-7
GCp = External Pressure Coefficents taken from ASCE 7-16 Figs. 30.3-2A-I through 30.3-7
Design Wind Pressure
Gable
Roof Zone*
Interior
34.7 psf
Hip
Roof Zone*
Interior
34.7 psf
Edge Corner
74.9 psf 84.3 psf
Edge Corner
61.3 psf 84.3 psf
Use 35 psf Use 75 psf Use 84 psf
Connection to Existing Roof Framing
F.S. = 1 Additional Factor of Safety applied to withdrawal force, if desired
Atrib = 21.60 ftZ
DLpane, = 3.00 psf
Interior Edge Corner
W pl;a = 34.7 psf 74.9 psf 84.3 psf
Piag = F.S. x A,,;b x (0.613 - 0.6W) Withdrawal force for each roof anchor
Interior Edge Corner
-410.8lbs-466.0lbs-263.5lbs
Page 5 of 6 vivi nt. s o u r
Connection Capacity
db = 5/16 in Lag Screw diameter
Dpen = 2.50 in Lag Screw penetration into existing framing member
Douglas Fir -Larch Species of wood framing
CD = 1.6 Load Duration Factor for Wind Loading, NDS Table 2.3.2
Ct = 0.7 Temperature Factor, NDS Table 10.3.4
W = 235 lb/in Withdrawal Capacity NDS Equation 12.2-1
W' = CD x C, x W = 263 lb/in Adjusted withdrawal value
fallow = Dpen x W' = 6571bs Based on penetration depth
Interior
DEMAND = 411 lbs
CAPACITY = 657 lbs
PLAN
Flat roof, 0 <- 7 degrees
Edge Corner
466lbs 264lbs
657 lbs 657 lbs Max Load=0.709 OK
PLAN
Gable roof
PLAN
Hip roof
*Note: Roof Zones considered are shown above. Worst case uplift from corner, edge or interior is used in design.
Page 6 of 6 V'V' nti sz. o I a