It is important to understand thermal barriers when it comes to proper installation of spray foam insulation, specifically what the ICC building code says about spray foam insulation. The building code specifically talks about foam plastic installation including spray foam, extruded polystyrene, ISO boards, and other forms of foam plastic insulation material.
The ICC building code says that all foam plastic insulations must be separated from the interior of the building by a 15-minute thermal barrier. Because foam is combustible, this code helps provide time for occupants to vacate the building in the event of fire.
One-half inch of gypsum board is the prescriptive thermal barrier of the building code. Gypsum board is comprised of crushed rock and is fire resistant. Gypsum board can be omitted as the thermal barrier by applying a cementitious-based product that passes a standalone thermal barrier test. This is spray applied over the surface.
Another option that is often considered is an intumescent coating. While technically an intumescent coating is not a thermal barrier, an intumescent coating tested over a specific spray foam can provide an interior finish system that omits the thermal barrier requirement. This can be desirable in open concept spaces, providing an interior finish that can be left exposed.
When using something other than half-inch gypsum board, the thermal barrier must meet the prescriptive requirements of the code. Thank you to Spray Foam Advisor for this valuable information. For more information we invite you to view the video to the right. Contact our office to discuss spray foam insulation and thermal barrier.