Intumescent materials are primarily used in firestop systems for what reason?

Intumescent materials play a crucial role in firestop systems because they expand significantly when exposed to high temperatures, effectively sealing gaps and openings in walls, floors, and ceilings. This expansion occurs during a fire, which helps prevent the passage of smoke and flames through these openings. The ability of intumescent materials to respond to heat makes them indispensable in enhancing the fire-resistance rating of a structure and ensuring that fire containment measures remain effective under extreme conditions.

While ease of installation, sound absorption, and electrical insulation are relevant properties in various contexts, they do not pertain to the primary function of intumescent materials within firestop systems. The significant characteristic of these materials is their thermal-responsive behavior, which aligns perfectly with the critical need for fire protection in construction and safety applications.