One-Part Expanding Firestop Spray Foam
This information reflects our best understanding of product composition in 2022.
Firestop spray polyurethane foam sealants, also called expanding firestop foam, are available as either a two-part system that is mixed on site or as a one-part material. The general composition for both types includes one or more isocyanate,...
Firestop spray polyurethane foam sealants, also called expanding firestop foam, are available as either a two-part system that is mixed on site or as a one-part material. The general composition for both types includes one or more isocyanate, polyol, catalyst, blowing agent, flame retardant, and surfactant. This Common Product describes one-part products, which were found to be more common. Some formulations contain intumescent materials or high global warming potential hydrofluorocarbon (HFC) blowing agents, but neither are common. For one-part spray foam systems, the isocyanate portion is mixed with the polyol portion, including additives, which react to some extent in the can; this creates a prepolymer that further reacts with moisture in the air when applied on site. In the case of one-part firestop spray foam sealants, the reaction product(s) could not be identified, so the unreacted polyols and isocyanates reported in product literature are listed in the common contents.
These sealants can be used in commercial or residential construction for penetration firestopping (such as HVAC, electrical, and plumbing) to impede the spread of fire, smoke, and toxic gases in the event of a fire. They can be used in fire-rated wall and ceiling assemblies and adhere to most common building materials. Because they cure by moisture absorption, manufacturers recommend moistening the surface with water prior to application of the foam. They are typically red or pink in color so they can be identified after installation.