Spray foam itself is combustible if directly exposed to flame. Building code requires a 'thermal barrier' (typically 1/2-inch drywall or DC315 paint) over foam in living spaces. Our Cincinnati installers handle both code-compliant assemblies.
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Spray polyurethane foam combusts at 400-500°F if exposed to direct flame, releasing carbon monoxide and other toxic gases. Building code (IRC R316) requires a thermal barrier between foam and the occupied space to give fire response time and limit toxic-smoke generation. The standard thermal barrier is 1/2-inch gypsum drywall installed over the foam in living spaces. For attics and crawl spaces where drywall is impractical, code allows specific intumescent paint coatings (DC315 by International Fireproof Technology is the dominant Cincinnati-area product) sprayed over the foam at the manufacturer-specified thickness. Both options are code-compliant; our Cincinnati installers spec the appropriate thermal barrier as part of the project scope. Some product/assembly combinations have ignition-barrier provisions that may allow exemption from the full thermal barrier; our technician confirms code compliance for the specific home and product. Cincinnati code-enforcement context: Cincinnati Building Department and Hamilton County Building Department both inspect foam installations for thermal-barrier compliance during permit-required projects. DC315 intumescent paint and 1/2-inch drywall are the two universally-accepted thermal barriers; alternative coatings exist but face more inspection variance. Our Cincinnati installers spec the appropriate barrier in the project quote and apply it as part of the original scope.