31B-086 JB-0101926-00 Reva_Calcs_ENP_MA_TBD s Version #54.7 - TBD
RE: CERTIFICATION LETTER
Project/Job # 0101926
Project Address: Griggs Residence
9 Barrett Place **COGEN**
Northampton, MA 01060
AHJ NorthamptonSC Office Springfield
Design Criteria:
- Applicable Codes = MA Res. Code, 8th Edition, ASCE 7-05, and 2005 NDS
- Risk Category = II
- Wind Speed = 90 mph, Exposure Category C
- Ground Snow Load = 40 psf
- MP6: Roof DL = 9.5 psf, Roof LL/SL = 28 psf (Non-PV Areas), Roof LL/SL = 16.4 psf (PV Areas)
- MP7: Roof DL = 9.5 psf, Roof LL/SL = 28 psf (Non-PV Areas), Roof LL/SL = 16.4 psf (PV Areas)
Note: Per IBC 1613.1; Seismic check is not required because Ss = 0.22462 < 0.4g and Seismic Design Category (SDC) = B < D
To Whom It May Concern,
March 11, 2016
A jobsite survey of the existing framing system of the address indicated above was performed by a site survey team from SolarCity.
Structural evaluation was based on site observations and the design criteria listed above.
Additionally, I certify that the PV module assembly including all standoffs supporting it have been reviewed to be in accordance with the
manufacturer’s specifications and to meet and/or exceed all requirements set forth by the referenced codes for loading.
Based on this evaluation, I certify that the existing structure directly supporting the PV system is adequate to withstand all loading
indicated in the design criteria above based on the requirements of the applicable existing building and/or new building provisions
adopted/referenced above.
The PV assembly hardware specifications are contained in the plans/docs submitted for approval.
Version #54.7 - TBD
X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP6 64''24''39''NA Staggered 44.3%
MP7 64''24''39''NA Staggered 44.3%
X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP6 48''20''65''NA Staggered 55.2%
MP7 48''20''65''NA Staggered 55.2%
Type Spacing Pitch
MP6 Pre-Fab Truss @ 16 in. O.C.35°
MP7 Pre-Fab Truss @ 16 in. O.C.35°
Member Evaluation Results
Member Impact Check OK
Member Impact Check OK
HARDWARE DESIGN AND STRUCTURAL ANALYSIS RESULTS SUMMARY TABLES
Mounting Plane Framing
Hardware - Portrait Modules' Standoff Specifications
Hardware - Landscape Modules' Standoff Specifications
Qualification ResultsStructure
Landscape
Hardware
Portrait
Hardware
Refer to the submitted drawings for details of information collected during a site survey. All member analysis and/or evaluation is based on framing information
gathered on site. The existing gravity and lateral load carrying members were evaluated in accordance with the IBC and the IEBC.
Overhang 1.66 ft Actual W 1.50''
Span 1 5.51 ft Actual D 3.50''
Number of Spans (w/o Overhang)2 Span 2 5.49 ft Nominal Yes
Roofing Material Comp Roof Span 3 A 5.25 in.^2
Re-Roof No Span 4 Sx 3.06 in.^3
Plywood Sheathing Yes Span 5 Ix 5.36 in.^4
Board Sheathing None Total Rake Span 15.46 ft TL Defl'n Limit 120
Vaulted Ceiling No PV 1 Start 1.33 ft Wood Species SPF
Ceiling Finish 1/2" Gypsum Board PV 1 End 14.67 ft Wood Grade #2
Rafter Slope 35°PV 2 Start Fb 875 psi
Rafter Spacing 16'' O.C.PV 2 End Fv 135 psi
Top Lat Bracing Full PV 3 Start E 1400000 psi
Bot Lat Bracing At Supports PV 3 End Emin 510000 psi
Roof Pitch 9/12 Initial Pitch Adjust Non-PV Areas PV Areas
Roof Dead Load DL 9.5 psf x 1.22 11.6 psf 11.6 psf
PV Dead Load PV-DL 3.0 psf x 1.22 3.7 psf
Roof Live Load RLL 20.0 psf x 0.78 15.5 psf
Live/Snow Load LL/SL1,2 40.0 psf x 0.7 ǀ x 0.41 28.0 psf 16.4 psf
Total Load (Governing LC)TL 39.6 psf 31.7 psf
Governing Load Comb CD CL (+)CL (-)CF Cr
D + S 1.15 1.00 0.93 1.5 1.15
Governing Analysis Pre-PV Demand Post-PV Demand Net Impact Result
Gravity Loading Check -725 psi -557 psi 0.77 Pass
Member Analysis Results Summary
Notes: 1. ps = Cs*pf; Cs -roof, Cs -pv per ASCE 7 [Figure 7-2] 2. pf = 0.7 (Ce) (Ct) (Is) pg ; Ce=0.9, Ct=1.1, Is=1.0
Member Design Summary (per NDS)
Roof System Properties
Member Loading Summary
STRUCTURE ANALYSIS - LOADING SUMMARY AND MEMBER CHECK - MP6
Member Properties Summary
MP6 Horizontal Member Spans Rafter Properties
Roofing Material
PV System Type
Spanning Vents
Standoff (Attachment Hardware)
Roof Slope
Rafter Spacing
Framing Type / Direction
Purlin Spacing X-X Purlins Only
Tile Reveal Tile Roofs Only
Tile Attachment System Tile Roofs Only
Standing Seam/Trap Spacing SM Seam Only
Wind Design Code
Wind Design Method
Basic Wind Speed V Fig. 6-1
Exposure Category Section 6.5.6.3
Roof Style Fig. 6-11B/C/D-14A/B
Mean Roof Height h Section 6.2
Wind Pressure Exposure Kz Table 6-3
Topographic Factor Kzt Section 6.5.7
Wind Directionality Factor Kd Table 6-4
Importance Factor I Table 6-1
Ext. Pressure Coefficient (Up)GCp (Up)Fig. 6-11B/C/D-14A/B
Ext. Pressure Coefficient (Down)GCp (Down)Fig. 6-11B/C/D-14A/B
Design Wind Pressure p Equation 6-22
Wind Pressure Up p(up)Wind Pressure Down p(down)
Y-Direction
Max Allowable Standoff Spacing Landscape 39''Max Allowable Cantilever Landscape NA
Standoff Configuration Landscape
Max Standoff Tributary Area Trib
PV Assembly Dead Load W-PV
Net Wind Uplift at Standoff T-actual
Uplift Capacity of Standoff T-allow
Standoff Demand/Capacity DCR
Y-Direction
Max Allowable Standoff Spacing Portrait 65''
Max Allowable Cantilever Portrait NA
Standoff Configuration Portrait
Max Standoff Tributary Area Trib
PV Assembly Dead Load W-PV
Net Wind Uplift at Standoff T-actual
Uplift Capacity of Standoff T-allow
Standoff Demand/Capacity DCR
22 sf3.0 psf
-276 lbs500 lbs
55.2%
500 lbs
44.3%
X-Direction
48''20''Staggered
Staggered
17 sf3.0 psf-221 lbs
13.1 psf
ALLOWABLE STANDOFF SPACINGS
X-Direction
64''
0.88
p = qh (GCp)
-14.2 psf
24''
qh qh = 0.00256 (Kz) (Kzt) (Kd) (V^2) (I)Equation 6-1515.0 psf
Wind Pressure
-0.95
Wind Pressure Calculation Coefficients
0.85
1.00
0.85
1.0
Velocity Pressure
15 ft
Wind Design Criteria ASCE 7-05
Partially/Fully Enclosed Method
90 mph
NA
C
Gable Roof
NA
NA
16'' O.C.
Y-Y Rafters
NA
No
Comp Mount Type C
35°
CALCULATION OF DESIGN WIND LOADS - MP6
Mounting Plane Information
Comp Roof
SolarCity SleekMount™
Overhang 1.66 ft Actual W 1.50''
Span 1 5.51 ft Actual D 3.50''
Number of Spans (w/o Overhang)2 Span 2 5.49 ft Nominal Yes
Roofing Material Comp Roof Span 3 A 5.25 in.^2
Re-Roof No Span 4 Sx 3.06 in.^3
Plywood Sheathing Yes Span 5 Ix 5.36 in.^4
Board Sheathing None Total Rake Span 15.46 ft TL Defl'n Limit 120
Vaulted Ceiling No PV 1 Start 1.33 ft Wood Species SPF
Ceiling Finish 1/2" Gypsum Board PV 1 End 14.67 ft Wood Grade #2
Rafter Slope 35°PV 2 Start Fb 875 psi
Rafter Spacing 16'' O.C.PV 2 End Fv 135 psi
Top Lat Bracing Full PV 3 Start E 1400000 psi
Bot Lat Bracing At Supports PV 3 End Emin 510000 psi
Roof Pitch 9/12 Initial Pitch Adjust Non-PV Areas PV Areas
Roof Dead Load DL 9.5 psf x 1.22 11.6 psf 11.6 psf
PV Dead Load PV-DL 3.0 psf x 1.22 3.7 psf
Roof Live Load RLL 20.0 psf x 0.78 15.5 psf
Live/Snow Load LL/SL1,2 40.0 psf x 0.7 ǀ x 0.41 28.0 psf 16.4 psf
Total Load (Governing LC)TL 39.6 psf 31.7 psf
Governing Load Comb CD CL (+)CL (-)CF Cr
D + S 1.15 1.00 0.93 1.5 1.15
Governing Analysis Pre-PV Demand Post-PV Demand Net Impact Result
Gravity Loading Check -725 psi -557 psi 0.77 Pass
Member Analysis Results Summary
Notes: 1. ps = Cs*pf; Cs -roof, Cs -pv per ASCE 7 [Figure 7-2] 2. pf = 0.7 (Ce) (Ct) (Is) pg ; Ce=0.9, Ct=1.1, Is=1.0
Member Design Summary (per NDS)
Roof System Properties
Member Loading Summary
STRUCTURE ANALYSIS - LOADING SUMMARY AND MEMBER CHECK - MP7
Member Properties Summary
MP7 Horizontal Member Spans Rafter Properties
Roofing Material
PV System Type
Spanning Vents
Standoff (Attachment Hardware)
Roof Slope
Rafter Spacing
Framing Type / Direction
Purlin Spacing X-X Purlins Only
Tile Reveal Tile Roofs Only
Tile Attachment System Tile Roofs Only
Standing Seam/Trap Spacing SM Seam Only
Wind Design Code
Wind Design Method
Basic Wind Speed V Fig. 6-1
Exposure Category Section 6.5.6.3
Roof Style Fig. 6-11B/C/D-14A/B
Mean Roof Height h Section 6.2
Wind Pressure Exposure Kz Table 6-3
Topographic Factor Kzt Section 6.5.7
Wind Directionality Factor Kd Table 6-4
Importance Factor I Table 6-1
Ext. Pressure Coefficient (Up)GCp (Up)Fig. 6-11B/C/D-14A/B
Ext. Pressure Coefficient (Down)GCp (Down)Fig. 6-11B/C/D-14A/B
Design Wind Pressure p Equation 6-22
Wind Pressure Up p(up)Wind Pressure Down p(down)
Y-Direction
Max Allowable Standoff Spacing Landscape 39''Max Allowable Cantilever Landscape NA
Standoff Configuration Landscape
Max Standoff Tributary Area Trib
PV Assembly Dead Load W-PV
Net Wind Uplift at Standoff T-actual
Uplift Capacity of Standoff T-allow
Standoff Demand/Capacity DCR
Y-Direction
Max Allowable Standoff Spacing Portrait 65''
Max Allowable Cantilever Portrait NA
Standoff Configuration Portrait
Max Standoff Tributary Area Trib
PV Assembly Dead Load W-PV
Net Wind Uplift at Standoff T-actual
Uplift Capacity of Standoff T-allow
Standoff Demand/Capacity DCR
22 sf3.0 psf
-276 lbs500 lbs
55.2%
500 lbs
44.3%
X-Direction
48''20''Staggered
Staggered
17 sf3.0 psf-221 lbs
13.1 psf
ALLOWABLE STANDOFF SPACINGS
X-Direction
64''
0.88
p = qh (GCp)
-14.2 psf
24''
qh qh = 0.00256 (Kz) (Kzt) (Kd) (V^2) (I)Equation 6-1515.0 psf
Wind Pressure
-0.95
Wind Pressure Calculation Coefficients
0.85
1.00
0.85
1.0
Velocity Pressure
15 ft
Wind Design Criteria ASCE 7-05
Partially/Fully Enclosed Method
90 mph
NA
C
Gable Roof
NA
NA
16'' O.C.
Y-Y Rafters
NA
No
Comp Mount Type C
35°
CALCULATION OF DESIGN WIND LOADS - MP7
Mounting Plane Information
Comp Roof
SolarCity SleekMount™