18C-063 165 Prospect0101841-00 RevB_Calcs_ENP_MA_TBD Version #53.6 - TBD
RE: CERTIFICATION LETTER
Project/Job # 0101841
Project Address: Le Residence
165 Prospect Ave
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
- MP1 & MP2: Roof DL = 9 psf, Roof LL/SL = 28 psf (Non-PV Areas), Roof LL/SL = 28 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,
January 25, 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 ASCE 7 standards for loading.
Based on this evaluationI 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 submitted for approval. Additionally a summary of the structural
review is provided in the results summary tables on the following page.
Version #53.6 - TBD
X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP1 & MP2 72''24''39''NA Staggered 44.6%
X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP1 & MP2 48''17''65''NA Staggered 49.5%
Type Spacing Pitch
MP1 & MP2 Pre-Fab Truss @ 24 in. O.C.22°
Member Evaluation Results
Member Analysis 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 2.82 ft Actual W 1.50''
Span 1 7.25 ft Actual D 3.50''
Number of Spans (w/o Overhang)2 Span 2 6.27 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 17.62 ft TL Defl'n Limit 120
Vaulted Ceiling No PV 1 Start 3.50 ft Wood Species SPF
Ceiling Finish 1/2" Gypsum Board PV 1 End 15.83 ft Wood Grade #2
Rafter Slope 22°PV 2 Start Fb 875 psi
Rafter Spacing 24'' 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 5/12 Initial Pitch Adjust Non-PV Areas PV Areas
Roof Dead Load DL 9.0 psf x 1.08 9.7 psf 9.7 psf
PV Dead Load PV-DL 3.0 psf x 1.08 3.2 psf
Roof Live Load RLL 20.0 psf x 0.95 19.0 psf
Live/Snow Load LL/SL1,2 40.0 psf x 0.7 ǀ x 0.7 28.0 psf 28.0 psf
Total Load (Governing LC)TL 37.7 psf 40.9 psf
Governing Load Comb CD CL (+)CL (-)CF Cr
D + S 1.15 1.00 0.91 1.5 1.15
Governing Analysis Max Demand @ Location Capacity DCR Result
Bending (-) Stress -1492 psi 10.1 ft -1580 psi 0.94 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 - MP1 & MP2
Member Properties Summary
MP1 & MP2 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
-247 lbs500 lbs
49.5%
500 lbs
44.6%
X-Direction
48''17''Staggered
Staggered
20 sf3.0 psf-223 lbs
10.0 psf
ALLOWABLE STANDOFF SPACINGS
X-Direction
72''
0.45
p = qh (GCp)
-13.1 psf
24''
qh qh = 0.00256 (Kz) (Kzt) (Kd) (V^2) (I)Equation 6-1515.0 psf
Wind Pressure
-0.88
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
24'' O.C.
Y-Y Rafters
NA
No
Comp Mount Type C
22°
CALCULATION OF DESIGN WIND LOADS - MP1 & MP2
Mounting Plane Information
Comp Roof
SolarCity SleekMount™