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76 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 />December 14, 2022 <br />Revised May 16, 2023 <br />EXO Energy <br />1247 Simpson Way <br />Escondido, CA 92029 <br />Re: Engineering Services <br />Vandervoort Residence <br />2307 North Towner Street, Santa Ana CA <br />7.200 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: Assumed prefabricated wood trusses at 24” on center. All truss members <br />are constructed of 2x4 dimensional lumber. <br />Roof Material: Concrete Tile & Composite Asphalt Shingles <br />Roof Slope: 20 degrees <br />Attic Access: Inaccessible <br />Foundation: Permanent <br />C.Loading Criteria Used <br />•Dead Load <br />o Existing Roofing and framing = 13 psf <br />o New Solar Panels and Racking = 3 psf <br />o TOTAL = 16 PSF <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 = 0 psf <br />•Wind Load based on ASCE 7-16 <br />o Ultimate Wind Speed = 95 mph (based on Risk Category II) <br />o Exposure Category C <br />Analysis performed of the existing roof structure utilizing the above loading criteria is in accordance <br />with the 2022 California Building Code, including provisions allowing existing structures to not <br />require strengthening if the new loads do not exceed existing design loads by 105% for gravity <br />elements and 110% for seismic elements. This analysis indicates that the existing framing will <br />support the additional panel loading without damage, if installed correctly. <br />2307 N Towner St - <br />2017896310/18/2023