13-020 JB-0102782-00_Calcs_ENP_MA_TBD Version #71.0 - TBD
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RE: CERTIFICATION LETTER
Project/Job # 0102782
Project Address: Sims Residence
20 Rockland Heights
Northampton, MA 01060
AHJ Northampton
SC Office Marlborough
Design Criteria:
- MP2: 4x6 @ 24'' OC, Roof DL = 9 psf, Roof LL/SL = 28 psf (Non-PV), Roof LL/SL = 28 psf (PV)
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,
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.
December 13, 2017
The PV assembly hardware specifications are contained in the plans/docs submitted for approval.
- Applicable Codes = MA Res. Code, 8th Edition / IEBC, ASCE 7-05, and 2005 NDS
- Risk Category = II
- Wind Speed = 90 mph, Exposure Category C, Partially/Fully Enclosed Method
- Ground Snow Load = 40 psf
A jobsite survey of the existing framing system of the address indicated above was performed by a site survey team from Tesla. Structural
evaluation was based on site observations and the design criteria listed above.
Based on this evaluation, I certify that the alteration to the existing structure by installation of the PV system, with upgrades specified in the
plans, meets the requirements of the applicable existing building and/or new building provisions adopted/referenced above.
Tesla, Inc.
3055 Clearview Way, San Mateo, CA 94402
p 650 638 1028 f 650 638 1029
Version #71.0 - TBD
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X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP2 72''24''39''NA Staggered 35.1%
X-X Spacing X-X Cantilever Y-Y Spacing Y-Y Cantilever Configuration Uplift DCR
MP2 48''18''65''NA Staggered 39.0%
Type Spacing Pitch
MP2 Stick Frame 24'' O.C.26°
Member Evaluation Results
Member Analysis OK w/ Upgrades as Specified in Plans
Hardware - Landscape Modules' Standoff Specifications
Qualification Results
HARDWARE DESIGN AND STRUCTURAL ANALYSIS RESULTS SUMMARY TABLES
Landscape
Hardware
Portrait
Hardware
Mounting Plane Framing
Hardware - Portrait Modules' Standoff Specifications
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 IEBC and the IBC.
Structure
Tesla, Inc.
3055 Clearview Way, San Mateo, CA 94402
p 650 638 1028 f 650 638 1029
Overhang 2.16 ft Net W 3.25''
Span 1 11.98 ft Equiv D 5.64''
Number of Spans (w/o Overhang)1 Span 2 Nominal No
Roofing Material Comp Roof Span 3 A (in^2)18.32
Re-Roof No Span 4 Sx (in.^3)17.21
Plywood Sheathing No Span 5 Ix (in^4)48.49
Board Sheathing Solid-Sheathing Total Rake Span 15.73 ft TL Defl'n Limit 120
Vaulted Ceiling No PV 1 Start 1.08 ft Wood Species SPF
Ceiling Finish 1/2" Gypsum Board PV 1 End 10.17 ft Wood Grade #2
Rafter Slope 26°PV 2 Start Fb (psi)875
Rafter Spacing 24'' O.C.PV 2 End Fv (psi)135
Top Lat Bracing Full PV 3 Start E (psi)1,400,000
Bot Lat Bracing At Supports PV 3 End E-min (psi)510,000
Roof Pitch 6/12 Initial Pitch Adjust Non-PV Areas PV Areas
Roof Dead Load DL 9.0 psf x 1.11 10.0 psf 10.0 psf
PV Dead Load PV-DL 3.0 psf x 1.11 3.3 psf
Roof Live Load RLL 20.0 psf x 0.90 18.0 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 38.0 psf 41.4 psf
Governing Analysis Max Moment @ Location Capacity DCR Result
(+) Bending Stress (psi)953.9 8.3 ft 1,504.3 63%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
Roof System Properties
STRUCTURE ANALYSIS - LOADING SUMMARY AND MEMBER CHECK - MP2
Member Loading Summary
STRUCTURE ANALYSIS - LOADING SUMMARY AND MEMBER CHECK - MP2
Member Properties Summary
MP2 Horizontal Member Spans Upgraded Rafter Properties
Roofing Material
Roof Slope
Framing Type / Direction
PV System Type
Zep System Type
Standoff (Attachment Hardware)
Spanning Vents
Design Code IBC 2009
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
-249 lbs
637 lbs
39.0%
Staggered
22 sf
3.0 psf
X-Direction
48''
18''
637 lbs
35.1%
20 sf
3.0 psf
-224 lbs
72''
24''
Staggered
ALLOWABLE STANDOFF SPACINGS
X-Direction
-13.1 psf
10.0 psf
-0.88
0.45
p = qh (GCp)
15.0 psf
Wind Pressure
1.00
0.85
1.0
Velocity Pressure qh qh = 0.00256 (Kz) (Kzt) (Kd) (V^2) (I)Equation 6-15
Gable Roof
15 ft
Wind Pressure Calculation Coefficients
0.85
Partially/Fully Enclosed Method
90 mph
C
No
Wind Design Criteria
ASCE 7-05
SolarCity SleekMount™
ZS Comp
Comp Mount Type C
ZEP HARDWARE DESIGN CALCULATIONS - MP2
Mounting Plane Information
Comp Roof
26°
Y-Y Rafters