What type of firestop will expand when exposed to heat or fire?

Intumescent firestop systems are specifically designed to expand when exposed to heat or fire. This characteristic is critical because the material swells significantly, sealing openings in walls, floors, and ceilings to prevent the spread of smoke and flames during a fire. The expansion of intumescent materials helps to fill gaps and maintain the integrity of fire-rated assemblies, effectively providing enhanced fire resistance and safety.

In contrast, non-combustible materials do not expand or react to heat; rather, they are designed to withstand high temperatures without igniting. Ablative materials might protect surfaces by absorbing heat and forming a charred layer, but they do not expand like intumescent materials. Flexible firestops are designed to accommodate movement and are not characterized by expansion under heat or fire but are instead formulated for various applications where some flexibility is required. Understanding these differences is crucial for selecting the appropriate firestop system for specific firestopping needs.