What type of building construction is most susceptible to collapse during fire?

Lightweight construction is most susceptible to collapse during a fire primarily due to the materials and methods used in its design. This type of construction often employs materials such as trusses, engineered wood, and other light framing techniques that, while efficient and cost-effective, can lose structural integrity rapidly when exposed to high heat.

In a fire situation, lightweight materials can fail unpredictably and quickly compared to heavier, more robust construction types. The structural components often have less mass, which means they do not retain heat as well and tend to reach failure temperatures much faster. This can lead to sudden and catastrophic collapses, posing significant risks to firefighters and occupants.

For example, wooden trusses, which are common in lightweight construction, can fail in as little as 5 to 15 minutes of sustained exposure to fire conditions. This is in stark contrast to steel frame construction, which while it can weaken under heat, generally maintains its structural integrity longer. On the other hand, reinforced concrete and brick and mortar constructions provide much greater resistance to fire due to their mass and thermal properties, thus making them less susceptible to collapse during fire scenarios.

Understanding these dynamics is crucial for firefighters when assessing risks at fire scenes and determining the safest approach for both firefighting operations and rescue efforts