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AOstructures Inc. <br />PO Box 413 <br />Carnelian Bay, CA 96140 <br />916.541.8586 <br />www.AOstructures.com <br />TO:Xero Solar <br />SUBJECT:Roof-top Solar PV Addition - 1671 E St. Andrews Pl. <br />1671 E St. Andrews Pl., Santa Ana, CA. 92705 <br />SCOPE OF WORK: <br />● <br />● <br />PROVIDED INFORMATION: <br />OBSERVED CONDITIONS: <br />CONCLUSIONS: <br />DESIGN CRITERIA: <br />● Applicable Codes = 2025 CBC, ASCE 7-22 <br />● Flush mounted rail based racking system w/ maximum allowed module dimensions of 88.8 in x 44.6 in <br />● Roof Dead Load = 16 psf (Roof A) <br />● Roof Live Load = 20 psf (reduced where allowed by ASCE7 - 1607.22.3) <br />● Wind Speed = 95 mph, Exposure B, Risk Category II <br />● Ground Snow Load = 3 psf - Roof Snow Load = 3 psf (LRFD), 2.1 psf (ASD) <br />Sincerely, <br />Andrew Oesterreicher, P.E. <br />Project Engineer <br />March 2, 2026 <br />AOstructures, Inc. was asked to provide a structural review for the project at the above subject location. The scope of this report is strictly limited to <br />the items listed below and based on the design criteria listed below. See additional limitations in Appendix B. <br />The observed roof framing is described below. If field conditions differ, the contractor shall notify the engineer prior to starting construction. <br />The existing roof framing members of (Roof A) are judged to be adequate to withstand the loading imposed by the installation of the solar panels. No <br />structural retrofits are required. <br />As-built plans were not provided for our review. The findings of this report are based upon a jobsite evaluation of the existing condition of the existing <br />framing system collected by Xero Solar as requested by AOstructures, Inc.. All attached structural calculations are based on the provided <br />information and are only deemed valid if the provided information is true and accurate. <br />The roof framing system of (Roof A) consists of built-up roof atop of plywood roof sheathing. The sheathing is supported by 2x sub-purlins spaced at <br />24" o.c. which span approxiatmely 8'-0" between pre-manufactured open web steel joists. The joists span between exterior walls or interior joist <br />girders. Exterior walls consist of concrete tilt-up elements conservatively assumed to be 6" thick. Wall panels are approximately 24'-0" tall. <br />The spacing of the solar standoffs shall not exceed 60" o.c. and be staggered. All racking hardware shall be installed per manufacturer specifications <br />and utilized within the manufacturers design limitations based on the design criteria of this report. AOstructures, Inc. assumes no responsibility for <br />hardware installed outside the design & install specifications of the manfacturer. All waterproofing shall be provided by the contractor. <br />Please contact me with any further questions or concerns regarding this project. <br />Analyze the existing structure(s) to see if it is/they are suitable to support the additional weight of the proposed roof mounted solar PV system. <br />Evaluate the connection capacity of the proposed racking system to the existing roof structure. <br />1671 - Westridge Labs, Santa Ana, CA.xlsx 1