Not knowing what unseen hazards they may encounter, veteran firefighters will tell you there’s always inherent risks in a our jobs. Within the fire fighting community, we know that one of the greatest hazards in firefighting is the threat of structural collapse.

Structural collapse of a building during fire fighting is a leading cause of death among fire fighters. The potential for structural collapse is one of the most difficult factors to predict during initial size-up and risk assessment, and, ongoing fire fighting. Structural collapse of any part of a building (floors, walls, ceilings, roofs, or structural members) during fire fighting often occurs without warning.

According to Deputy Chief Vincent Dunn’s book “Collapse of Burning Buildings: A Guide to Fireground Safety”: upon arrival at a fire scene, in order to determine the structural integrity of a burning building, the incident commander (IC) should consider the following factors: “extent of fire and location, the amount of time the fire has been burning, conditions on arrival, size of the building (single or multistory, floor area, and height), age of the building (deterioration of structural members, and any evidence of weathering), use of lightweight materials in new construction, presence of combustible materials, occupancy, renovations or modifications to the building, previous fires, and supported loads (such as roof-top heating and cooling systems) that might affect the structural integrity of the building.”

Consider that in the future this threat to the firefighters safety will only get worse, as we see the impact of fire on the lightweight engineered wood components being used today in new construction. Residential buildings are increasingly replacing conventional solid joist construction with modern lightweight construction, such as lightweight wood trusses and engineered I-beams, which are used as both roof and floor supports. Under normal conditions these contemporary construction components are said to have the same or better load-carrying capacities as old-fashioned conventional construction, but don’t perform as well under fire conditions mainly because there is less wood to burn, leaving fire crews no margin for safety for the fire crews entering the burning structure.

Firefighters should accept the fact that these new construction materials are here to stay. They are cheaper, and easier to handle than conventional building materials. So understanding the many hazards of lightweight construction will help incident commanders, company officers, and firefighters to evaluate the hazards present prior to and during a given incident and allow a more informed risk/benefit analysis when choosing tactics (offensive/defensive) to be used.

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