Is Spray Foam a Fire Hazard or a Fire Barrier?
Both. Spray Foam only chars, does not self-sustain combustion, and will extinguish once an external flame source is removed. Spray Foam is also thermoset, not thermoplastic; meaning that it does not return to liquid form once it is cured. These properties make Spray Foam a great fire barrier. For example, if the common wall between a warehouse and a showroom is sealed with Spray Foam a fire can burn in the warehouse all night and the showroom would remain untouched. However, it is the super insulating properties of Spray Foam that make it a fire hazard. The heat from a fire inside a building completely sealed with Spray Foam will be reflected back to the fire and cause the fire to burn hotter and quicker. For this reason a code approved fire barrier must be installed over Spray Foam in living spaces. ½” drywall is an approved fire barrier for this.