What type of firestop is specifically designed to expand when exposed to heat?

The type of firestop specifically designed to expand when exposed to heat is the intumescent firestop. Intumescent materials are engineered to react to high temperatures by expanding significantly, which helps to fill gaps and prevent the passage of fire, smoke, and gases through openings in fire-rated walls, floors, and ceilings. This expansion creates a solid, insulating barrier that effectively seals the voids caused by penetrations, thereby enhancing the fire-resistance rating of the assembly.

Intumescent firestops are commonly used in various applications, such as around electrical conduits, plumbing pipes, and cable trays. The unique property of expansion upon heating distinguishes these firestops from other types that may not react in the same way or do not have the capability to significantly alter their physical properties in response to fire conditions. This characteristic is particularly critical in maintaining the integrity of fire-resistance-rated assemblies during a fire event.

In contrast, fire sealants are often used but do not provide the same expansion capabilities. Ablative firestops focus on dissipating heat rather than expanding, and passive firestops refer to various methods that prevent fire spread without active response to heat. Understanding these distinctions highlights the importance of using intumescent firestops in fire protection