Developing contingency plans for buildings being razed
NFPA Journal®, September/October 2011
All kinds of buildings, from high-rises to single-family homes, are demolished every day for a variety of reasons. Fire departments must be aware of scheduled demolitions so they can develop contingency plans for fires, entrapments, and other emergencies that could occur while buildings are being razed. The fire department should also visit the site of a demolition before and during the operation.
In addition to problems associated with a particular wrecking operation, firefighters should be aware of problems that may be encountered when a building is intentionally destroyed. Explosives are often used to implode large structures, and the contractor and building owner must work closely with the fire department to ensure safety, not only on the day of the scheduled implosion, but during preparation, especially when explosives are on site. Other hazardous materials may also be encountered at a demolition site, especially if the building was previously inhabited by an industrial occupancy that used chemicals in its manufacturing process. Many abandoned buildings sit vacant for years with chemicals stored inside deteriorating containers.
Even a single-family home can present problems during demolition. Contractors sometimes fail to shut off all the utilities or remove asbestos or other problem materials before razing the building using heavy construction equipment. While such equipment makes short work of the job, it can also create a problem if the property wasn’t thoroughly prepped.
Regardless of a structure’s size, a careful evaluation is needed when responding to a fire in a partially demolished building. Contractors remove salvageable materials before major demolition begins, but it’s not unusual for scavengers to illegally enter vacant structures scheduled for demolition to strip copper wiring, flooring, plumbing fixtures, or anything else of value. This can be especially dangerous, because untrained people removing building materials from weakened structures can cause an immediate collapse.
As demolition continues, interior and exterior walls that could contain a fire and stabilize the structure are removed. This greatly increases the potential for collapse and rapid fire spread, presenting extraordinary hazards for firefighters. Compounding the problem is debris that presents tripping and falling hazards, especially in stairways. Stairways and elevators may be unusable, making it difficult to access a building’s upper floors. In most cases, fire protection equipment is removed or damaged very early in the demolition process.
Conducting a risk-versus-benefit analysis in a building being demolished is not always as easy as it may appear. Although it might seem that there is no chance that anyone is in the building and that the building has no value, people and savable property may, in fact, be in the structure or on nearby property. Workers are typically spread around the demolition site during work hours, but the building could also be illegally occupied by a range of trespassers after crews leave for the day.
According to NFPA statistics, 49 percent of all reported structure fires in buildings being demolished are intentionally set. Intentional or not, fires that occur after work crews leave can easily gain considerable headway before being reported, allowing the fire time to spread throughout the structure and involve external exposures. Free-burning fires involving wooden framing, combustible building materials, or debris can rapidly develop into large fires that produce high levels of radiant heat. Flying brands can also be a problem; brands from a fire at a building under construction in California ignited buildings a half-mile away.
All of these factors, and the potential to save endangered lives and property, underscore the need to devise a plan to fight fires in these kinds of buildings.
This column is adapted from the author's book StructuralFireFighting, available online or (800) 344-3555.