What is the purpose of intumescent materials in firestopping?

The purpose of intumescent materials in firestopping is to expand in response to heat. When a fire occurs, these materials undergo a chemical reaction that causes them to swell significantly. This expansion fills gaps and spaces in firestop systems, effectively sealing openings to prevent the passage of flames, smoke, and hot gases. This attribute is crucial during a fire, as it helps maintain the integrity of fire-rated assemblies and slows the spread of fire to other areas, thereby enhancing safety. Intumescent materials are designed specifically for this response, making them an essential component in effective firestop systems.