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SOLG . N <br /> P O W E R <br /> July 21, 2022 <br /> Subject: Proposed Solar Panel Installation <br /> Stephanie Dunnihoo Residence, 3502 Rockefeller 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 for the proposed installation. Based on our review and analysis of the available <br /> information, it is our professional opinion that the existing structure requires a retrofit to ensure structural <br /> adequacy to support the proposed installation. <br /> The retrofit shall consist of fixing broken blocking inbetween the existing 2x4 rafters, with 16d common nails at 24" <br /> O.C., staggered. <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: 2x4 Rafters @ 24" O.C. <br /> Roofing Material:Asphalt Shingles(1 layer) <br /> Roof Slope: 32 degrees <br /> Roof Connection Details <br /> RT Minis into 2x rafters or truss top chords at 48" O.C., install per design drawings and manufacturer specs <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 2.59 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 />