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CONSSLING <br /> %'... <br /> 476 North Meadowbrook Drive <br /> Scott E. Wyssling, PE Alpine, UT 84004 <br /> Coleman D. Larsen, SE, PE office (201) 874-3483 <br /> Gregory T. Elvestad, PE swyssling@wysslingconsulting.com <br /> September 30, 2022 <br /> Revised October 27, 2022 <br /> Revised December 6, 2022 <br /> Revolution Solar <br /> 9981 West 190th Street <br /> Unit K, Mokena, IL <br /> Re: Engineering Services <br /> Boop Residence <br /> 1510 108th Street Southwest, Everett, WA <br /> 8.160 kW System <br /> To Whom It May Concern: <br /> We have received information regarding solar panel installation on the roof of the above referenced <br /> structure. Our evaluation of the structure is to verify the existing capacity of the roof system and its ability <br /> to support the additional loads imposed by the proposed solar system. <br /> A. Site Assessment Information <br /> 1. Site visit documentation identifying attic information including size and spacing of framing <br /> for the existing roof structure. <br /> 2. Design drawings of the proposed system including a site plan, roof plan and connection <br /> details for the solar panels. This information will be utilized for approval and construction <br /> of the proposed system. <br /> B. Description of Structure: <br /> Roof Framing: Prefabricated wood trusses at 24" on center. All truss members are <br /> constructed of 2x4 dimensional lumber. <br /> Roof Material: Composite Asphalt Shingles <br /> Roof Slope: 20 degrees <br /> Attic Access: Accessible <br /> Foundation: Permanent <br /> C. Loading Criteria Used <br /> • Dead Load <br /> o Existing Roofing and framing = 7 psf <br /> o New Solar Panels and Racking = 3 psf <br /> o TOTAL = 10 PSF <br /> • Live Load = 20 psf(reducible)—0 psf at locations of solar panels <br /> • Ground Snow Load = 20 psf <br /> • Wind Load based on ASCE 7-16 <br /> o Ultimate Wind Speed = 110 mph (based on Risk Category ll) <br /> o Exposure Category C <br /> Analysis performed of the existing roof structure utilizing the above loading criteria is in accordance <br /> with the 2018 Washington State Residential Code(2018 IRC), including provisions allowing existing <br /> structures to not require strengthening if the new loads do not exceed existing design loads by <br /> 105%for gravity elements and 110%for seismic elements. This analysis indicates that the existing <br /> framing will support the additional panel loading without damage, if installed correctly. <br />