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OBSERVED CONDITIONS: CONCLUSIONS: LIMITATIONS: Praneet R Erusu, P.E. Principal Engineer Erusu Consultants US Inc. The observed roof framing is described below. If field conditions differ, the contractor shall notify the engineer prior to starting construction. The roof framing is supported by 2x12 Rafters @ 16" O.C are spanning between load bearing walls. The maximum allowed clear span of rafter is 17ft, to be verified in field by the contractor. Based upon our review, we conclude that the existing structure is adequate to support the proposed solar panel installation. In the area of the solar array, other live loads will not be present or will be greatly reduced (2022 CBC, Section 1607.14.4). The gravity loads and the stresses of the structural elements, in the area of the solar array are either decreased or increased by no more than 5%. Therefore, the requirements of Section 503.3 of the 2022 CEBC are met and the structure is permitted to remain unaltered. The solar array will be flush-mounted (no more than 6" above the roof surface) and parallel to the roof surface. Thus, we conclude that any additional wind loading on the structure related to the addition of the proposed solar array is negligible. The attached calculations verify the capacity of the connections of the solar array to the existing roof against wind (uplift), the governing load case. Regarding seismic loads, we conclude that any additional forces will be small. Conservatively neglecting the weight of existing wall materials, the installation of the solar panels represents an increase in the total weight (and resulting seismic load) of 3.0%. Because the increase in lateral forces is less than 10%, this addition meets the requirements of the exception in Section 503.4 of the 2022 CEBC. Thus the existing lateral force resisting system is permitted to remain unaltered. Installation of the solar panels must be performed in accordance with manufacturer recommendations. All work performed must be in accordance with accepted industry-wide methods and applicable safety standards. Existing Roof and structural members are assumed to be in good and serviceable condition. The contractor must notify Erusu Consultants US Inc. should any damage, deterioration or discrepancies between the as-built condition of the structure and the condition described in this letter be found. Connections to existing roof framing must be staggered, except at array ends, so as not to overload any existing structural member. The use of solar panel support span tables provided by others are allowed only where the building type, site conditions, site-specific design parameters, and solar panel configuration match the description of the span tables. The design of the solar panel racking (mounts, rails, etc.) and electrical engineering is the responsibility of others. Waterproofing around the roof penetrations is the responsibility of others. Erusu Consultants US Inc. assumes no responsibility for improper installation of the solar array. 27 Apr 2023 EXP : 30 Sep 2023 1430 N Baker St 06/12/23