3M™ Fire Block Foam FB-Foam is a fireblock and Draftstop® used to help seal, fill, insulate and bond for non-rated residential and commercial construction. This foam-in-place fireblock is heat-resistant (up to 240 deg F/115 deg C) and meets ASTM E-84 (mod) Class 1 for smoke spread and flame development. This fireblock foam is ready-to-use and tack-free in approximately 5 min.