Jo Landers Letter SS
Wyssling Consulting
76 North Meadowbrook Drive
Alpine, UT 84004
Scott E. Wyssling, PE, PP, CME office (201) 874-3483
swyssling@wysslingconsulting.com
July 11, 2021
Ken Trappen Advanced Solar Solutions 39650 Mallard
Bass Lake, CA 93604
Re: Engineering Services Jo Landers 6 Service Center Road #2, Northampton MA 15.050 kW System
Dear Mr. Trappen: Pursuant to your request, we have reviewed the following information regarding solar panel installation on the roof of the above referenced structure:
1. Site Visit/Verification Form prepared by Advanced Solar Solutions representative identifying specific site information including size and spacing of rafters for the existing roof structure. 2. Design drawings of the proposed system including a site plan, roof plan and connection details for the solar panels. This information was prepared by Advanced Solar Solutions
and will be utilized for approval and construction of the proposed system. 3. Photographs of the interior and exterior of the roof system identifying existing structural members and their conditions.
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:
Description of Structure: The existing structure is a wood- and steel-framed building utilizing 2 x 10 dimensional lumber rafters at 16” spacing supported by W14x48 steel beams spaced at approximately 14 feet on center. The W14 beams
span the width of the building and are supported by CMU columns. The attic space is finished, and photos indicate that access to visually inspect the size and condition of the roof rafters was created by removing a small area of sheetrock from the ceiling. All wood material utilized for the roof system is assumed to be Doug-Fir #2 or better, and all steel utilized is assumed to be ASTM A572 Gr 50 or better, all utilizing
standard construction connections and details. The existing roofing material consists of membrane roofing. Photos of the dwelling also indicate that there is a permanent foundation. A. Loading Criteria Used
• 117 MPH wind loading based on ASCE 7-10 Exposure Category “C” at a slope of 2 degrees
• 7 PSF = Dead Load roofing/framing Live Load = 20 PSF Snow Load = 40 PSF
• 3 PSF = Dead Load solar panels/mounting hardware
Total Dead Load =10 PSF
The above values are within acceptable limits of recognized industry standards for similar structures in accordance with the Massachusetts Uniform Construction Code (2015 IBC). Analysis performed of the existing roof structure utilizing the above loading criteria indicates that the existing rafters will support the additional panel loading without damage, if installed correctly.
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B. Solar Panel Anchorage
1. The solar panels shall be mounted to the ballast system in accordance with the most recent “Ecolibrium Installation Manual”, which can be found on the Ecolibrium website (http://ecolibriumsolar.com/). 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. 2. Ballast system shall be placed on the roof in accordance with Ecolibrium recommended layout and per there installation instructions.
Based on the above evaluation, it is the opinion of this office that the standard installation will adequately support the additional loading imposed by the solar panels. This evaluation is in conformance with the Massachusetts Uniform Construction Code, current industry and standards, and based on information supplied
to us at the time of this report. Should you have any questions regarding the above or if you require further information do not hesitate to contact me.
Very truly yours,
Scott E. Wyssling, PE MA License No. 50507