Reliance on sprinklers a mistake
Many building codes, which establish fire safety standards for public and private buildings, are based upon the mistaken assumption that sprinklers virtually never fail and that fire-resistant construction materials can, therefore, be minimized or eliminated.
However, the National Fire Protection Association has data showing that sprinklers do not operate about 16% of the time. The figure is based on a 10-year study of more than 8,000 commercial and industrial fires in the U.S.
Despite the risk of failure, there is a trend for model codes to rely increasingly on sprinklers, while reducing requirements for fireproofing, fire-resistant doors, dampers, and other fire and smoke barriers. At the same time, municipalities are considering adopting codes that allow buildings to be constructed taller and wider, with more open, flexible space.
While many view fire barriers as costly excess, firefighters and other emergency responders see them as lifesavers: The more fire- and smoke-resistant construction products that are designed into a sprinklered structure, the less likely it is that it will collapse during a fire.
Those who doubt the need for fire-resistant construction need only look at the results of the World Trade Center Building Performance Study, which I oversaw in the aftermath of 9/11. While the WTC disaster involved impact trauma that the buildings' designers never envisioned, the sprinklers were overwhelmed. However, the additional fire-resistant construction is believed to have helped reduce the death toll by delaying collapse of the twin towers.
Evidence of the vulnerability of sprinkler systems in more conventional fires can be seen in Buildings 5 and 7 of the WTC complex. Building 7 is not believed to have been seriously impacted by the collapse of the towers; Building 5 did have some severe damage from falling debris, but much of the building was undamaged. Both buildings had sprinkler systems. Yet Building 7 and a portion of Building 5 collapsed from burnout fires. The sprinklers in Building 5 were overwhelmed by the intensity of the fire; in Building 7, there was either no water supply or insufficient water to combat fire and prevent its collapse.
Based upon these findings, it is clear that the fire protection provided by the sprinkler systems alone did not stop the fires in these two buildings. However, the built-in fire protection delayed their collapse, thereby allowing occupants and emergency responders to evacuate both buildings.
Why is this important now? Two years after 9/11, New York City is gearing up to adopt the new International Building Code. Regrettably, the IBC relies even more extensively on sprinklers than previous model building codes at the expense of fire-resistant construction materials.
In fact, the IBC's requirements for fire-resistant construction are drastically lower than what building codes required two to three decades ago. The IBC allows buildings to have more stories, more open space, narrower stairwells, longer distances to an exit, and fewer exits than is permissible under other codes. Unless the code is amended, it will place occupants, firefighters, and other emergency responders at greater risk than ever before.
This has implications well beyond New York. If history holds true, amendments made to the IBC in New York City will be carefully scrutinized by other jurisdictions across the country.
Fire safety cannot be an either/or proposition. Buildings for which sprinklers are appropriate should also have fire-resistant construction for better fire protection. Anything less puts occupants and emergency responders at risk and is unacceptable.
W. Gene Corley, PhD, Senior VP, Construction Technology Laboratories, Skokie, Ill., and team leader for the WTC Building Performance Study.