By Vincent Dunn
Each building type has a fire-resistive construction weakness that creates a reoccurring fire spread problem. Knowing how a fire can spread throughout a structure helps a fire officer quickly extinguish a fire and, more importantly, protects firefighters from becoming caught and trapped by fire.
Most fires start in the contents of a building–a smoldering cigarette ignites a fire in a stuffed chair or mattress, or something similar. If flames are not quickly extinguished, they extend to the structure. The fire spreads throughout concealed spaces, poke-through holes, and then behind walls, floors, and ceiling spaces, eventually engulfing the common roof or attic spaces and ultimately destroying the entire building. In addition to interior fire spread, flames can spread over the outside of the burning building, from window to window and across combustible exterior wood siding. Extinguishing a structure fire is much more complex than extinguishing a contents fire. First, the concealed flames must be located, then the walls and ceilings must be opened up with pike poles, and finally hose streams must cut off fire before it reaches the common roof space or attic.
Fire officers must know the basic construction types and understand the various ways flames can spread throughout each type of burning building.
Deputy Chief Dunn (Ret., Fire Department of New York) is the author of a number of textbooks, including the new Strategy of Firefighting (Fire Engineering, 2007), Collapse of Burning Buildings (Fire Engineering, 1988), Safety and Survival on the Fireground (Fire Engineering, 1992), and Command and Control of Fires and Emergencies (Fire Engineering, 1999).