Which firestopping material is defined as expanding when heated?

Which firestopping material is defined as expanding when heated?

• A. Ablative
• B. Intumescent
• C. Cementitious
• D. Epoxy

Answer: (B)

Understanding how firestopping materials respond to heat: some are designed to expand to fill gaps, forming an insulating barrier that blocks flames and hot gases from passing through openings. The material that expands when heated is the intumescent type. When exposed to high temperatures, it activates blowing agents and swells many times its original size, creating a protective char and a tight seal around openings for pipes, cables, and ducts. This expansion is what makes it effective at maintaining fire resistance during a fire. In contrast, ablative materials work by burning away to carry heat with them rather than expanding; cementitious fillings are rigid and do not swell; epoxies do not expand and may degrade under heat.