What essential condition should be fulfilled for firestop systems to function effectively?

For firestop systems to function effectively, proper sealing of joints is critical. This ensures that any openings or penetrations in fire-rated walls, floors, or ceilings are effectively sealed to prevent the passage of smoke, fire, and hot gases between different areas. When joints are not properly sealed, there is an increased risk of fire spreading beyond its origin, compromising the integrity of the fire resistance rated assemblies. Proper sealing helps to maintain the intended fire resistance rating of the construction and is an essential aspect of a firestop system's design and installation.

While other factors like temperature maintenance or moisture control may play supportive roles in the overall performance of materials used in firestopping systems, they do not directly address the fundamental requirement of adequately sealing gaps and joints which is paramount for preventing the spread of fire and smoke.