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SOLGr- N <br /> P O W E R <br /> July 12, 2021 <br /> Subject: Proposed Solar Panel Installation <br /> Dale Hamilton Residence, 1915 122nd PL SE, Everett,WA 98208 <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 <br /> with governing building codes, it is our professional opinion that the existing structure is permitted to remain <br /> unaltered 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: 97 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 <br /> Roof Slope: 17 degrees <br /> Roof Connection Details <br /> Lag Screws: 5/16" diameter min., with min. 2.5" 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 2.57 psf. In the <br /> areas where panels are installed, roof live loads will not be present. Also, where applicable, roof snow loads will be <br /> reduced because the slippery surface of the panels will cause the roof to shed additional snow loads relative to the <br /> existing roof surface. The reduction of roof live and snow load is adequate to fully or partially compensate for the <br /> addition of the panel installation. Because the member forces in the area of the solar panels are not increased by <br /> more than 5%, the stresses in the members are not increased by more than 5%, and so per section 806.2 of the <br /> International Existing Building Code (IEBC),the structure need not be altered for 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 />