BSOL2022-0477 - Structual CalcsProject :
Project Number:
By :
Date :
UNIRAC
1411 Broadway Blvd, NE
Albuquerque, NM 87102
RE: Solar Array Installation at 48615 Calle Esperanza, La Quinta, CA 92253, USA
To Whom it May Concern,
CODE REFERENCES:
BUILDING CODE: 2019 CALIFORNIA BUILDING CODE
2018 INTERNATIONAL BUILDING CODE
ASCE 7-16
SCOPE OF WORK:
DESIGN PARAMETERS
RISK CATEGORY :
DESIGN WIND SPEED : mph
WIND EXPOSURE :
GROUND SNOW LOAD : psf
SEISMIC DESIGN CATEGORY :
EXISTING ROOF STRUCTURE
ROOF : 2x4 Trusses @ 24" O.C.
ROOF MATERIAL : W Tile
CONNECTION TO ROOF STRUCTURE
MOUNTING CONNECTION :(2) 5/16" LAG BOLTS w/ MIN. 2.5" EMBEDMENT INTO (E) 2x FRAMING MEMBER
@ MAX. 72" o.c. ALONG RAILS
(2) RAILS PER ROW OF PANELS, EVENLY SPACED. PANEL LENGTH
PERPENDICULAR TO RAIL NOT TO EXCEED 70.63"
II
110
C
0
*null
Mona Davidson
PE
26-09-2022
Roof structural framing plan has been reviewed for additional loading due to installation of the roof mounted
solar PV addition. The structural review that follows, including plans and calculations, only apply to the section of
the roof that is directly supporting the solar PV system and its supporting elements.
26 September 2022
Per your request, we have reviewed the existing structure at the above referenced site. The purpose of our review
was to determine the adequacy of the existing structure to support the proposed installation of solar panels on the
roof per layout plan
BSOL2022-0477
7.4kW PV SYSTEM
09/27/2022
OBSERVED CONDITIONS:
CONCLUSIONS:
LIMITATIONS:
Praneet R Erusu, P.E.
Principal Engineer
Erusu Consultants US Inc.
The observed roof framing is described below. If field conditions differ, the contractor shall notify the engineer
prior to starting construction. The roof framing is supported by 2x4 Trusses @ 24" O.C are spanning between
load bearing walls. The maximum allowed span of 2x top chord member between panel points is 8ft.
Based upon our review, we conclude that the existing structure is adequate to support the proposed solar panel
installation. In the area of the solar array, other live loads will not be present or will be greatly reduced (2019 CBC,
Section 1607.13.5). The glass surface of the solar panels allows for a lower slope factor per ASCE 7, resulting in
reduced design snow load on the panels. The gravity loads and the stresses of the structural elements, in the area
of the solar array are either decreased or increased by no more than 5%. Therefore, the requirements of Section
503.3 of the 2019 CEBC are met and the structure is permitted to remain unaltered.
We conclude that any additional wind loading on the structure related to the addition of the proposed solar array
is negligible. The attached calculations verify the capacity of the connections of the solar array to the existing roof
against wind (uplift), the governing load case. Regarding seismic loads, we conclude that any additional forces will
be small. Conservatively neglecting the weight of existing wall materials, the installation of the solar panels
represents an increase in the total weight (and resulting seismic load) of 2.1%. Because the increase in lateral
forces is less than 10%, this addition meets the requirements of the exception in Section 503.4 of the 2019 CEBC.
Thus the existing lateral force resisting system is permitted to remain unaltered.
Installation of the solar panels must be performed in accordance with manufacturer recommendations. All work
performed must be in accordance with accepted industry-wide methods and applicable safety standards. Existing
Roof and structural members are assumed to be in good and serviceable condition. The contractor must notify
Erusu Consultants US Inc. should any damage, deterioration or discrepancies between the as-built condition of
the structure and the condition described in this letter be found. Connections to existing roof framing must be
staggered, except at array ends, so as not to overload any existing structural member. The use of solar panel
support span tables provided by others are allowed only where the building type, site conditions, site-specific
design parameters, and solar panel configuration match the description of the span tables. The design of the solar
panel racking (mounts, rails, etc.) and electrical engineering is the responsibility of others. Waterproofing around
the roof penetrations is the responsibility of others. Erusu Consultants US Inc. assumes no responsibility for
improper installation of the solar array.
26 Sep 2022
EXP : 30 Sep 2023
Project :
Project Number:
By :
Date :
Address :
Site Plan:
Mona Davidson
PE
26-09-2022
48615 Calle Esperanza, La Quinta, CA 92253, USA
Project :
Project Number:
By :
Date :
Roof Dead Load
Roof Slope = :
Angle =
Roof Live Load
Roof Live Load = psf (Refer ASCE 7-16, Table 4.3-1)
Roof Live Load with PV Array = psf 2019 CBC, Section 1607.13.5
(Ceiling load and MEP is assumed to be not supported by rafter)
20
0
PV Array 3 1.05
2.2 1.05
MEP & Misc. 1.5
W Tile 12 1.05
4 12
18
Material
Material Weight
(psf)
2.32
1.50
21.32
1/2" Plywood 1.1 1.05
Framing 3 1.05
3.16
1/2" Gypsum Ceiling
Mona Davidson
PE
26-09-2022
DL =
Increase due to
Roof Slope
Plan Projected Materal
Weight (psf)
12.65
1.16
3.16
0.53Insulation 0.5 1.05
Project :
Project Number:
By :
Date :
Mona Davidson
PE
26-09-2022
Summary of Gravity Loads
Dead Load, D = psf
Roof Live Load, Lr = psf
Gravity Load Comparision
(D + Lr)/Cd = psf
(Cd = 0.9 for D, 1.15 for S, 1.25 for Lr)
Max Loading = psf
Proposed to Current Loading Ratio =O.K.
Gravity Loading with PV Array is not stressing the current framing system by more that 5% of the original
configuration. Per Section 503.3 of 2019 California Existing Building Code the sturcure is allowed to remain
unaltered for gravity loading
39.69 27.20
69%< 105%
39.69 27.20
20.00 0.00
Existing With PV Array
Existing With PV Array
21.32 24.48
Wood Beam
LIC# : KW-06014559, Build:20.22.3.31 ERUSU CONSULTANTS US (c) ENERCALC INC 1983-2022
DESCRIPTION:2x4 Truss Top Chord @ 24" o.c. (Wind Condition)(Strength Check)
Project File: 2x4 Truss_Copy.ec6
Project Title:
Engineer:
Project ID:
Printed: 26 SEP 2022, 2:51PM
Project Descr:
CODE REFERENCES
Calculations per NDS 2018, IBC 2018, CBC 2019, ASCE 7-16
Load Combination Set : ASCE 7-16
Material Properties
Beam Bracing :Beam is Fully Braced against lateral-torsional buckling Repetitive Member Stress Increase
Allowable Stress Design
Douglas Fir-Larch
No.2
900.0
900.0
1,350.0
625.0
1,600.0
580.0
180.0
575.0 31.210
Analysis Method :
Eminbend - xx ksi
Wood Species :
Wood Grade :
Fb +
psi
psi
Fv psi
Fb -
Ft psi
Fc - Prll psi
psiFc - Perp
E : Modulus of Elasticity
Ebend- xx ksi
Density pcf
Load Combination :ASCE 7-16
.Applied Loads Service loads entered. Load Factors will be applied for calculations.
Beam self weight NOT internally calculated and added
Load for Span Number 1
Uniform Load : D = 0.00810 ksf, Tributary Width = 2.0 ft, (Existing Roof Dead Load)
Point Load : D = 0.0530, W = 0.2840 k @ 4.0 ft, (Solar Panel Load)
Point Load : D = 0.0530, W = 0.2840 k @ 7.580 ft, (Solar Panel Load)
Uniform Load : Lr = 0.020, W = 0.01610 ksf, Extent = 0.0 -->> 4.0 ft, Tributary Width = 2.0 ft, (Existing Wind, & Roof Live Load)
Load for Span Number 2
Uniform Load : D = 0.00810 ksf, Tributary Width = 2.0 ft, (Existing Roof Dead Load)
Point Load : D = 0.0530, W = 0.2840 k @ 4.0 ft, (Solar Panel Load)
Point Load : D = 0.0530, W = 0.2840 k @ 7.580 ft, (Solar Panel Load)
Uniform Load : Lr = 0.020, W = 0.01610 ksf, Extent = 0.0 -->> 4.0 ft, Tributary Width = 2.0 ft, (Existing Wind & Roof Live Load)
.DESIGN SUMMARY Design OK
Maximum Bending Stress Ratio 0.998: 1
Load Combination +D+0.750Lr+0.750L+0.450W+H
Span # where maximum occurs Span # 1
Location of maximum on span 8.000ft
136.92 psi=
=
2,484.00 psi
2x4Section used for this span
Span # where maximum occurs
Location of maximum on span
Span # 1=
Load Combination +D+0.60W+H
=
=
=
288.00 psi==
Section used for this span 2x4
Maximum Shear Stress Ratio 0.475 : 1
7.732 ft=
=
2,479.24 psi
Maximum Deflection
0 <180
258
Ratio =384944 >=120
Max Downward Transient Deflection 0.379 in 253Ratio =>=180
Max Upward Transient Deflection 0 in Ratio =
Max Downward Total Deflection 0.372 in Ratio =>=120
Max Upward Total Deflection -0.000 in
fb: Actual
Fb: Allowable
fv: Actual
Fv: Allowable
Span: 2 : W Only
n/a
Span: 2 : +D+0.750Lr+0.750L+0.450W+H
Span: 2 : +D+0.60W+H
.Maximum Forces & Stresses for Load Combinations
Span #
Moment ValuesLoad Combination
C i C LCCCCF/V mr td
Shear ValuesMax Stress Ratios
M CV fbM fvF'b V F'vSegment Length
+D+H 0.00 0.00 0.000.00
1.00Length = 8.0 ft 1 0.631 0.292 0.90 1.500 1.15 1.00 1.00 0.22 881.31 1397.25 0.17 162.001.00 47.23
1.00Length = 8.0 ft 2 0.631 0.292 0.90 1.500 1.15 1.00 1.00 0.22 881.31 1397.25 0.12 162.001.00 47.23
Wood Beam
LIC# : KW-06014559, Build:20.22.3.31 ERUSU CONSULTANTS US (c) ENERCALC INC 1983-2022
DESCRIPTION:2x4 Truss Top Chord @ 24" o.c. (Wind Condition)(Strength Check)
Project File: 2x4 Truss_Copy.ec6
Project Title:
Engineer:
Project ID:
Printed: 26 SEP 2022, 2:51PM
Project Descr:
Maximum Forces & Stresses for Load Combinations
Span #
Moment ValuesLoad Combination
C i C LCCCCF/V mr td
Shear ValuesMax Stress Ratios
M CV fbM fvF'b V F'vSegment Length
1.00+D+L+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.568 0.262 1.00 1.500 1.15 1.00 1.00 0.22 881.31 1552.50 0.17 180.001.00 47.23
1.00Length = 8.0 ft 2 0.568 0.262 1.00 1.500 1.15 1.00 1.00 0.22 881.31 1552.50 0.12 180.001.00 47.23
1.00+D+Lr+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.777 0.314 1.25 1.500 1.15 1.00 1.00 0.38 1,508.25 1940.63 0.25 225.001.00 70.61
1.00Length = 8.0 ft 2 0.777 0.314 1.25 1.500 1.15 1.00 1.00 0.38 1,508.25 1940.63 0.25 225.001.00 70.61
1.00+D+S+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.494 0.228 1.15 1.500 1.15 1.00 1.00 0.22 881.31 1785.38 0.17 207.001.00 47.23
1.00Length = 8.0 ft 2 0.494 0.228 1.15 1.500 1.15 1.00 1.00 0.22 881.31 1785.38 0.12 207.001.00 47.23
1.00+D+0.750Lr+0.750L+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.696 0.273 1.25 1.500 1.15 1.00 1.00 0.34 1,351.52 1940.63 0.21 225.001.00 61.37
1.00Length = 8.0 ft 2 0.696 0.273 1.25 1.500 1.15 1.00 1.00 0.34 1,351.52 1940.63 0.21 225.001.00 61.37
1.00+D+0.750L+0.750S+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.494 0.228 1.15 1.500 1.15 1.00 1.00 0.22 881.31 1785.38 0.17 207.001.00 47.23
1.00Length = 8.0 ft 2 0.494 0.228 1.15 1.500 1.15 1.00 1.00 0.22 881.31 1785.38 0.12 207.001.00 47.23
1.00+D+0.60W+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.960 0.475 1.60 1.500 1.15 1.00 1.00 0.61 2,384.94 2484.00 0.48 288.001.00 136.92
1.00Length = 8.0 ft 2 0.960 0.475 1.60 1.500 1.15 1.00 1.00 0.61 2,384.94 2484.00 0.33 288.001.00 136.92
1.00+D+0.750Lr+0.750L+0.450W+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.998 0.442 1.60 1.500 1.15 1.00 1.00 0.63 2,479.24 2484.00 0.45 288.001.00 127.36
1.00Length = 8.0 ft 2 0.998 0.442 1.60 1.500 1.15 1.00 1.00 0.63 2,479.24 2484.00 0.36 288.001.00 127.36
1.00+D+0.750L+0.750S+0.450W+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.809 0.398 1.60 1.500 1.15 1.00 1.00 0.51 2,009.03 2484.00 0.40 288.001.00 114.50
1.00Length = 8.0 ft 2 0.809 0.398 1.60 1.500 1.15 1.00 1.00 0.51 2,009.03 2484.00 0.27 288.001.00 114.50
1.00+0.60D+0.60W+0.60H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.818 0.410 1.60 1.500 1.15 1.00 1.00 0.52 2,032.41 2484.00 0.41 288.001.00 118.03
1.00Length = 8.0 ft 2 0.818 0.410 1.60 1.500 1.15 1.00 1.00 0.52 2,032.41 2484.00 0.28 288.001.00 118.03
1.00+D+0.70E+0.60H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.355 0.164 1.60 1.500 1.15 1.00 1.00 0.22 881.31 2484.00 0.17 288.001.00 47.23
1.00Length = 8.0 ft 2 0.355 0.164 1.60 1.500 1.15 1.00 1.00 0.22 881.31 2484.00 0.12 288.001.00 47.23
1.00+D+0.750L+0.750S+0.5250E+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.355 0.164 1.60 1.500 1.15 1.00 1.00 0.22 881.31 2484.00 0.17 288.001.00 47.23
1.00Length = 8.0 ft 2 0.355 0.164 1.60 1.500 1.15 1.00 1.00 0.22 881.31 2484.00 0.12 288.001.00 47.23
1.00+0.60D+0.70E+H 1.500 1.15 1.00 1.00 0.00 0.00 0.001.00 0.00
1.00Length = 8.0 ft 1 0.213 0.098 1.60 1.500 1.15 1.00 1.00 0.13 528.79 2484.00 0.10 288.001.00 28.34
1.00Length = 8.0 ft 2 0.213 0.098 1.60 1.500 1.15 1.00 1.00 0.13 528.79 2484.00 0.07 288.001.00 28.34
.
Location in SpanLoad CombinationMax. "-" Defl Location in SpanLoad Combination Span Max. "+" Defl
Overall Maximum Deflections
W Only 1 0.3786 3.531 0.0000 0.000
W Only 2 0.3741 4.514 0.0000 0.000
.
Load Combination Support 1 Support 2 Support 3
Vertical Reactions Support notation : Far left is #1 Values in KIPS
Overall MAXimum 0.219 0.857 0.363
Overall MINimum 0.174 0.857 0.363
+D+H 0.066 0.292 0.113
+D+L+H 0.066 0.292 0.113
+D+Lr+H 0.166 0.492 0.133
+D+S+H 0.066 0.292 0.113
+D+0.750Lr+0.750L+H 0.141 0.442 0.128
+D+0.750L+0.750S+H 0.066 0.292 0.113
+D+0.60W+H 0.170 0.806 0.331
+D+0.750Lr+0.750L+0.450W+H 0.219 0.827 0.292
+D+0.750L+0.750S+0.450W+H 0.144 0.677 0.277
+0.60D+0.60W+0.60H 0.144 0.689 0.286
+D+0.70E+0.60H 0.066 0.292 0.113
+D+0.750L+0.750S+0.5250E+H 0.066 0.292 0.113
+0.60D+0.70E+H 0.040 0.175 0.068
Wood Beam
LIC# : KW-06014559, Build:20.22.3.31 ERUSU CONSULTANTS US (c) ENERCALC INC 1983-2022
DESCRIPTION:2x4 Truss Top Chord @ 24" o.c. (Wind Condition)(Strength Check)
Project File: 2x4 Truss_Copy.ec6
Project Title:
Engineer:
Project ID:
Printed: 26 SEP 2022, 2:51PM
Project Descr:
Load Combination Support 1 Support 2 Support 3
Vertical Reactions Support notation : Far left is #1 Values in KIPS
D Only 0.066 0.292 0.113
Lr Only 0.100 0.200 0.020
W Only 0.174 0.857 0.363
H Only
Project :
Project Number:
By :
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Wind Load Calculation
Wind Loads - ASCE 7-16 Chapter 26 & 29
Width of the Building, B = ft (Approximate)
V = mph
Exposure =
Average height of building, z = ft - avg (Approximate)
ft (Refer ASCE 7-16, Table 26.10-1)
α =Zg =ft (Refer ASCE 7-16, Table 26.11-1)
Kh & Kz =2.01(z/Zg)^(2/α) =
Kzt =(Refer ASCE 7-16, Equation 26.8-1)
Kd =(Refer ASCE 7-16, Table 26.6.1)
Ke =(Refer ASCE 7-16, Table 26.9-1)
qh ='.00256 KzKztKdKeV² =psf (Refer ASCE 7-16, Section 26.10-1)
Building Classification =
Solar Panel
Components and Cladding p C&C = qh(GCp)(ϒe)(ϒa)ASCE 7-16 Chaper 29.4.4
Module Length =in
Module Width =in
Area of Module =ft2
Roof Pitch =:
Slope =degrees
Hip Roof =
ϒe=
ϒa= (Refer ASCE 7-16, Figure 29.4-8)
12
18
20.2
70.63
7° < θ ≤ 20°
1.5
22.35
4.0
41.19
110
C
15
0.85
Enclosed
0.8
zmin = 15
9.5
1
47.2
1
0.85
Mona Davidson
PE
26-09-2022
900
Project :
Project Number:
By :
Date :
Mona Davidson
PE
26-09-2022
Zone 1 Uplift
External Wind pressure coefficient GCp =
External Wind pressure, qGCp = psf
Zone 2 Uplift
External Wind pressure coefficient GCp =
External Wind pressure, qGCp = psf
All Zone Downward
External Wind pressure coefficient GCp =
External Wind pressure, qGCp = psf
Maximum Uplift Wind Pressure, p = psf
Minimum Downward Wind Pressure ,p =psf
Lag Screw / Bolt Connection Check (ASD)
Tributary Width =in (Max Spacing of fastners along Rails)
Tributary Length =in (Half Panel Length)
Tributary Area =ft2
Lag Screw/Bolt Size =
Cd = (Refer NDS Table 2.3.2)
Embedment = in
Grade of Wood = #2 ( or better)
G =
Capacity = lb/in (Refer NDS Table 12.2A)
Number of Screws in Tension =
Prying Coefficient =
Capacity of Fasteners = lb
Demand
Zone 1
Zone 2 0.45
Pressure ASD (0.6W)(psf)
-29.0
-38.6 17.7 682.0 1520
DCR
17.7 511.5 1520 0.34
Capacity (lb)Tributary Area (ft2) Uplift (lb)Zone
0.5
266
2
1.4
1520
72
0.6
16.1
(Measured from top of the framing member to tapered tip of lag screw,
embeddment in sheathing and tapered tip of screw is not included )
DF
-64.37
-1.8
-48.28
-64.37
16.1
35.315
17.7
5/16
1.6
2.5
-2.4
Project :
Project Number:
By :
Date :
Seismic Ground Motion Values
Mona Davidson
PE
26-09-2022
Project :
Project Number:
By :
Date :
Seismic Design Force
Seismic Loads - ASCE 7-16 Chapter 13
Seismic Force
Component Amplification Factor, ap= (Refer ASCE 7-16, Table 13.6 -1)
Overstrength Factor, Ωo = (Refer ASCE 7-16, Table 13.6 -1)
Component Importance Factor, Ip=
SDS =
Average roof height of structure,h =ft
z/h =z/h should not exceed 1
Frame Weight Wp = psf
Seismic Design Force on Solar framing structure
Max Fp =1.6 x SDS x Ip X Wp =psf
Min Fp =0.3 x SDS x Ip X Wp =psf
Seismic Design Load Fp =psf
Vertical Seismic Design Load Fp =psf0.76
3.04
6.07
1.14
3.16
FP = ((0.4 x ap x SDS x Wp)/ (Rp / Ip)) x
((1+2(z/h)) =3.04 psf
15
1
Height in structure at point of attachement,
z =
15 ft
1.00
1.50
1.20
1.00
Seismic Coefficients for Mechanical
and Electrical components =
Component Response Modification
Factor, Rp=
1.50
Mona Davidson
PE
26-09-2022
12 Other mechanical or electrical components.
(Refer ASCE 7-16, Table 13.6 -1)
Project :
Project Number:
By :
Date :
Mona Davidson
PE
26-09-2022
Check for Increase in overall seismic loads
Array Area =ft2
Number of Arrays =
Total Array Area =ft2
Array Load = psf
Number of Existing Arrays =
Exisitng Area =ft2
Total Array Wt. = lb
Total Roof Area =ft2
DL of Roof = psf
Total Wt of Roof = lb
Increase in Seismic Wt = <
21.32
56576
2.1% 10%
Conservativelsy the Wt. of the Walls tributary to the roof is not included. Seismic weight increase is less thaan
10% and no seismic retrofit or evaluation of existing lateral system is required per Section 503.4 of 2019
CEBC.
20.2
20
404.06
2654.1
3.00
1212.2
0
0.00