Soudafoam Fire Retardant PU Gun Foam. A one component, self-expanding, ready to use polyurethane foam. Perfect for the fire retardant sealing and filling of joints and openings between walls, floors and ceilings. The foam has a fire classification of up to 240 minutes according to EN13501-2 (EN1366-4:2009). Fire retardancy in minutes depends on the joint configuration.