Which term describes materials that swell to provide a fire seal when exposed to heat?

The term "intumescent" specifically refers to materials that expand in volume when heated, creating a fire-resistant seal. This property is vital in fire protection systems, as intumescent materials can prevent the spread of flames and smoke through gaps and openings in walls, floors, and ceilings. When exposed to high temperatures, typically during a fire, these materials will swell and form a char that acts as a barrier, thereby enhancing fire safety.

In the context of firestop systems, intumescent materials are often used in various applications, including around pipes, electrical cables, and other penetrations, to maintain the integrity of fire-rated assemblies. The ability to expand and form a protective seal makes intumescent materials critical components in passive fire protection strategies.

Other terms, such as "endothermic," "elastomeric," and "thermal," describe different properties or behaviors of materials but do not specifically capture the function of swelling to create a fire seal. Endothermic refers to a process that absorbs heat, elastomeric pertains to materials that can stretch and then return to their original shape, and thermal generally relates to heat in a broader context without implying any specific fire-resistance behavior.