BOSS 814 UL Classified Intumescent Latex Firestop Sealant is a one part, elastomeric, intumescent firestop sealant that expands when exposed to fire or extreme heat, forming an insulated char. BOSS 814 will prevent the spread of toxic gases, smoke and fire. It is suitable for adhesion to almost any surface and remains flexible, making it ideal for both horizontal and vertical joints, subject to vibration or dynamic movement. BOSS 814 can be used for interior or exterior applications, and can be painted (after inspection). Tested to ASTM E-814 (UL 1479) and meets the criteria for fire/smoke/draft stop for BOCA-CABO-UBC-SBCCI-IRC.