When it comes to fire testing, the benchmark for a thermal barrier, as it pertains to spray foam insulation, is half-inch gypsum wallboard. In fact, gypsum board, or drywall, is the prescriptive thermal barrier defined by the International Building Code (IBC) and International Residential Code (IRC).
Materials not defined in the IBC or IRC can meet non-prescriptive thermal barrier standards by performing at least as well as drywall during both a temperature transmission test and a fire integrity test. In certain cases, the temperature transmission test can be waived, and a material can be accepted as an alternative assembly, provided it performs acceptably during a large-scale fire test, such as UL 1040, UL 1715, FM 4880, or NFPA 286. The latter test, often called the room corner burn test, is the most commonly used test for fire-retardant coatings in the spray foam industry. NFPA 286-06 does not publish pass/fail criteria. The test standard describes that flashover has occurred when any TWO of the following conditions have been met…..