By Vincent Dunn
The best-kept secret in Americas fire service is that firefighters cannot extinguish a fire in a high-rise office building. A fully involved office floor area of 10 or 20 thousand square feet is too large. It is beyond any fire company's ability to extinguish that much flame with a hose stream. A fire company advancing a 2 ½-inch hoseline with a 1⅛-inch nozzle discharges 250 gallons per minute, and it can extinguish about 2,500 square feet of fire. Two lines, side by side, can handle maybe 5,000 square feet of fire.
A modern open-floor office design, with cubicle work stations and dwarf partitions that do not extend to the ceiling, allows fire to spread throughout an entire office-floor area. A couple of firefighters spraying a hose stream from a stairway cannot extinguish a fully involved, free-burning, 20,000-square-foot floor-area fire. . City managers and department chiefs will not admit this to the public if they want to keep their jobs, but every fire chief working in a high-rise district knows this is a fact.
What really happens at a serious high-rise fire is called "controlled burning." Firefighters operating the hose stream in a doorway maintain a defensive position in the stairway for as long as it takes for all the combustible contents to be consumed by flames. This may be two hours, four hours, or eight hours.
To successfully contain a high-rise fire to one floor and not kill large numbers of occupants attempting to escape, you need 40 to 50 firefighters using a rapid-response, blitz attack. If this fails, it will take another 100 to 200 additional firefighters to control the fire and keep it from spreading to floors above. If a community does not have large numbers of firefighters available, then every square foot of every high-rise building in town had better be fully protected by automatic sprinklers.
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).