How quickly do trusses typically fail during a fire?

Trusses are designed to provide strength and structural integrity, but during a fire, they can fail more rapidly than one might expect. While the general belief may be that they can withstand longer durations, fire exposure significantly weakens the materials used in truss construction—especially wood.

Typically, trusses will begin losing their structural integrity within the first few minutes of exposure to intense heat. The timeframe of approximately 5-10 minutes is based on various studies that observe how temperature affects the performance of building materials. After being exposed to combustion gases and high temperatures, the wood and metal connectors in trusses can weaken rapidly, leading to a potential collapse.

Understanding this timeframe is crucial for firefighters, as it highlights the importance of making quick and informed decisions regarding firefighting tactics and evacuation procedures. Knowing that trusses can fail within this 5-10 minute window emphasizes the need for fire crews to be aware of their environment and the risks associated with the structural components of a building under fire.