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PPurefight Power <br /> February 17, 2024 <br /> Subject: Proposed Solar Panel Installation <br /> Josh Good Residence, 1310 Maple St, 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: 2x4 Rafters @ 24" O.C. <br /> Roofing Material:Asphalt Shingles(1 layer) <br /> Roof Slope: 26°, 30° <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 complies with the requirements of WAC Section 51-51-03240 R324.4 (Exception) and is <br /> therefore deemed adequate to support the load of the rooftop solar system. <br /> Specifically: 1) the system is designed for the local wind speed; 2) the ground snow load does not exceed 70 psf; 3) <br /> the total dead load of all items is less than 4 psf(actual value is approximately2.75 psf);4) Modules are not mounted <br /> more than 18" off the roof; and 5) Supports are installed such that the dead load is spread across roof-framing <br /> members and does not exceed 50 lbs at any point. <br /> Wind uplift on the panels has been calculated in accordance with the relevant provisions of ASCE 7-16. This loading <br /> has been used to verify the adequacy of the connection specified above. Connection locations should be in <br /> accordance with design drawings. <br />