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G:\Forms & Handouts - 2026\Residential Projects - 2026\18. Re-Roof Rated Sheathing (2025).docx Page 1 of 1 Re-roof Using Rated Plywood or OSB Sheathing Over Existing Skipped Sheathing • The sheathing must be 7/16 inch nominal or larger, exterior type, with a stamp indicating “CDX” or “Exposure Also, the stamp must indicate the sheathing is “rated”. CRC R803.2.1.1 • Sheathing shall be installed perpendicular to the rafters and supported over a minimum of three rafters. The horizontal edge of the sheathing shall bear on a parallel skipped sheathing board or provide support clips at 24-in on center. The ends of the sheathing shall be centered over the rafters and nailed with 8D nails or 13 gauge staples (minimum 2 inches long with 7/16 crown) at 6-in on center maximum at ends and 12-in on center maximum in the field. Special attention shall be given to drive the nails and staples through both the sheathing and the rafter. • If the rafters are not spaced at the standard 16-in or 24-in on center spacing, an alternate method can be used to secure the sheathing. Secure the sheathing to the rafter nearest the end of the sheathing, with spacing at 6-in on center maximum. Secure the end of the sheathing to the skipped sheathing with one fastener per skipped sheathing board, maximum 12-in on center. Use the same fasteners as specified above. • Request an inspection from the Building Division for the roof sheathing after the installation of the sheathing has been completed. Once the building inspector has signed the “inspection record”, the roof covering may be installed. • Verify with building inspector for exceptions according to weather conditions.