What does 'percent compression' indicate in the context of firestop systems?

'Percent compression' in the context of firestop systems refers to the proportion of sealant that can be compressed in service. This metric is crucial because it helps to determine how well the firestop will perform when subjected to various conditions, such as movement in the building's structure or temperature changes that can affect the materials in use.

A firestop system is designed to maintain the integrity of fire-resistance-rated assemblies, and understanding percent compression ensures that the sealant can accommodate any expected joint movement while still providing a reliable barrier against flames, smoke, and hot gases. Properly designed firestop systems will remain effective through full cycles of expansion and contraction, which the percent compression measurement helps to quantify.

In contrast, the other options do not correctly define what 'percent compression' signifies. The first option suggests a fixed amount to compress during installation rather than in-service capability. The third option misleadingly refers to fire containment, which is more about the overall effectiveness of the firestop system rather than a specific measurement like percent compression. The fourth option relates to movement but doesn't directly address the compressibility of the sealant itself during operation.