A firestop is a fire protection system made of various components employed to seal openings and joints in fire-resistance rated wall or floor assemblies. Firestops are designed to restore the fire-resistance ratings of wall and/or floor assemblies preventing the spread of fire by filling the openings with fire-resistant materials. Unprotected openings in fire separations cancel out the fire-resistance ratings of the fire separations, allowing the spread of fire. Firestop components include intumescents, cementitious mortars, silicone, firestop pillows, mineral fibers, and rubber compounds.
A penetration, in firestopping, is an opening, such as one created by the use of a cast-in-place sleeve, in a wall or floor assembly required to have a fire-resistance rating, for the purpose of accommodating the passage of a mechanical, electrical or structural penetrant.