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SOLG . N <br /> P O W E R <br /> January 27, 2022 <br /> Subject: Proposed Solar Panel Installation <br /> Aaron Gay Residence, 3904 Federal Ave, Everett,WA <br /> To Whom it May Concern, <br /> Our engineering department has reviewed information, gathered by our field crews, related to the proposed solar <br /> panel installation at the above-referenced address. The purpose of our review was to determine the structural <br /> adequacy of the existing roof. Based on our review and analysis of the available information, and in accordance with <br /> governing building codes, it is our professional opinion that the existing structure is permitted to remain unaltered <br /> for the proposed solar installation. <br /> Design Parameter Summary <br /> Governing Building Code: 2018 Washington Building Code (2018 IBC) <br /> Risk Category: II <br /> Design Wind Speed: 110 mph (per ASCE 7-16) <br /> Ground Snow Load: 15 psf <br /> Roof Information <br /> Roof Structure: 2x6 Rafters @ 24" O.C. <br /> Roofing Material:Asphalt Shingles(1 layer) <br /> Roof Slope: 26 degrees <br /> Roof Connection Details <br /> Lag Screws: 5/16" diameter min.,with min. 1.5" embedment into framing members,at 48" O.C. max,staggered <br /> Locations per design drawings <br /> Note:Required embedment length excludes the tapered tip of the screw,and embedment into sheathing. <br /> Analysis <br /> The proposed installation - including weight of panels, racking, and mounts - will be approximately 2.76 psf. In the <br /> areas where panels are installed, roof live loads will not be present. The reduction of roof live load is adequate to <br /> fully or partially compensate for the addition of the panel installation. Because the member forces in the area of the <br /> solar panels are not increased by more than 5%, the stresses in the members are not increased by more than 5%, <br /> and so per section 806.2 of the International Existing Building Code (IEBC), the structure need not be altered for <br /> gravity loading. <br /> The proposed installation will be 6" max. above the roof surface (flush mounted) and parallel to the roof surface. <br /> Therefore, any increase in wind loading on the building structure from the solar panel installation is expected to be <br /> negligible. Wind is the governing lateral load case. Because the increase in lateral loading is not increased by more <br /> than 10%, per section 806.3 of the adopted IEBC,the structure need not be altered for lateral loading. <br />