Standard polyurethane spray foam, including products marketed as ‘Great Stuff’ or generic gun foam, is an insulating material. It carries no fire rating and is not approved for firestopping fire-rated assemblies.

Firestop foam is a different chemistry. It is intumescent, which means it expands and chars when heated, forming a fire-resistant barrier. Firestop foams are tested to UL 1479 or ASTM E814 and listed under specific UL Listed Systems that detail the exact substrate, penetrant and configuration tested.

Using a non-rated spray foam in a fire-rated penetration is a code violation and creates a life-safety liability. Always specify a UL classified firestop foam such as TENMAT FF360 for through-penetrations in fire-rated walls, floors and ceilings.