Which stage of fire development is likely to be the last before a total collapse?

The last stage of fire development before a total collapse is the fully developed stage. During this phase, the fire has reached its peak intensity and has consumed the available fuel and oxygen in the environment. The fire exhibits maximum heat release, and all combustible materials are typically involved in burning.

In structures, the fully developed stage can lead to significant weakening of structural components due to intense heat, causing them to lose integrity. As materials such as steel and wood are exposed to high temperatures, they may begin to warp, weaken, or break down, ultimately leading to structural failure and collapse.

Understanding fire behavior in the fully developed stage is crucial for emergency responders, as it helps them assess risks and make tactical decisions based on the stability of the structures involved.