BY FRANCIS L. BRANNIGAN, SFPE (FELLOW)
Editor’s note: For further reference, consult Building Construction for the Fire Service, Third Edition (BCFS3). Page numbers are included after each caption (when applicable) for your convenience.
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Firefighters might use this cantilevered supermarket canopy for access to a fire on the roof.
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College and other multibuilding facilities often have utility or pedestrian tunnels that connect buildings. The old Wanamaker’s department store in New York City was being demolished. A fire started in the three-story-high pile of scrap flooring in the basement. It took massed 21/2-inch lines “shoulder-to-shoulder” in the tunnel that connected the old building to the new building to prevent fire extension.
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The cantilevered beams extend through the wall; the load is transferred upward to the roof trusses by compression members. A fire-caused failure of the trusses would let one end of the “see-saw” go up and the other end go down. As the beams rotate through the masonry wall, they would probably pull the wall down on the firefighters. Being under or on top of this canopy could be fatal if fire is attacking the roof trusses.
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In this apartment house, the floors are made of a paper composition board. I was told it had passed the inadequate “blowtorch test.” The hole cut through it provides a perfect ignition point. Hidden pipes have provided a secret path for fire spread since indoor plumbing was invented.
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At this incident, all the attention was directed to the visible fire, which was in the section that has collapsed. The fire sneaked undetected around the firewall through the mansard, and now there is a whole new fire. Some codes read, “The fire wall shall extend from exterior wall to exterior wall.” The architect takes advantage of the wording to leave the mansard wide open. Sometimes, an effort is made to firestop the mansard, but don’t rely on it. The mansard should be opened up and a heavy-caliber hose stream used to prevent fire extension.
FRANCIS L. BRANNIGAN, SFPE (Fellow), the recipient of Fire Engineering’s first Lifetime Achievement Award, has devoted more than half of his 59-year career to the safety of firefighters in building fires. He is well known as the author of Building Construction for the Fire Service, Third Edition (National Fire Protection Association, 1992) and for his lectures and videotapes. Brannigan is an editorial advisory board member of Fire Engineering.
