How does intumescence function in firestop products?

Intumescence operates by expanding when exposed to heat, which is a crucial property of certain firestop products. When the temperature rises, intumescent materials undergo a physical and chemical reaction that causes them to swell significantly, forming a thick, char-like barrier. This expansion helps to fill gaps and voids around penetrations, effectively blocking the passage of smoke, flames, and heat. This reactive property is fundamental in maintaining the integrity of fire-rated assemblies and ensuring safety during a fire event.

The correct functioning of intumescence is essential for the performance of firestop systems, as it enhances their effectiveness in creating fire-resistive barriers. This property is what allows firestop products to meet specific fire-resistance ratings and comply with safety codes and standards.