IRC R908 reroof — two-layer maximum and when tear-off is required

International Residential Code Section R908 governs reroofing and draws a clear distinction between a roof recover and a roof replacement. A recover (R908.3.1) adds a new layer of roof covering over the existing covering and is not permitted on a roof that already carries two or more layers of any covering type. A replacement (R908.3) includes removal of existing layers of roof covering down to the roof deck and is the path required when the two-layer threshold has already been reached, when the existing covering is water-soaked or deteriorated, or when the existing covering type prohibits recover. Specific code-listed exceptions allow recover without removal in defined circumstances — new protective coating over an existing protective coating, metal panel or shingle, mineral-surfaced roll roofing, built-up roof, modified bitumen, thermoset and thermoplastic single-ply, and spray polyurethane foam systems — but these exceptions are narrow and tied to the existing roofing material type. Texas does not adopt the IRC statewide; local jurisdictions adopt their own editions, and the windstorm program (cross-reference D5-001) adopts a specific edition for the catastrophe area. Where R908 is adopted, the two-layer maximum is part of the applicable building code; confirming the edition that applies to a specific address is the contractor's responsibility. The same homeowner can also face manufacturer warranty implications layered on top of the code: many major shingle manufacturer warranties contain language voiding coverage if the new shingle is installed over a non-conforming existing covering, which can be a separate reason to tear off even when code allows a recover. [Source: 2021 International Residential Code Chapter 9 Section R908; 2024 International Residential Code Chapter 9 Section R908; International Code Council]