Is spray-on fireproofing, joint compound or mortar an adequate firestop in construction joints?
NO! All material used in firestopping joints such as top or head of wall, perimeter/curtain-wall gap, control joints, etc. will have to pass a cyclical test (500-cycles – UL 2079) and then pass the fire and hose stream test in a fully extended situation. This means that cementitious fireproofing, tape/joint compound or firestopping mortar (typically pink, red, or brown) that is commonly used by drywall contractors at the head of sheetrock walls is definitely out. The problem with these type of materials is that with any movement of the assembly, cracks occur which can allow fire, smoke and toxic fumes through. A material that has expansion and compression characteristics is required.
