What does solidity refer to in a firestop system?

In the context of a firestop system, solidity pertains to the strength of the bond created by the sealant. This bond is crucial because it determines how effectively the firestop will function to prevent the passage of fire, smoke, and hot gases through openings and joints in fire-resistance-rated assemblies. A strong bond ensures that the sealant adheres effectively to the surfaces it's applied to, enhancing the overall integrity and performance of the firestop during a fire event.

While the thickness of the firestop seal, the flexibility of the materials used, and the rate of application are important factors in the overall effectiveness of a firestop system, they do not specifically define the concept of solidity. Thickness might influence the thermal barrier, flexibility could relate to movement and expansion, and application rate could affect coverage, but it is the strength of the bond that is foundational to ensuring the firestop's ability to maintain its integrity under fire conditions.