BY FRANCIS L. BRANNIGAN,SFPE (FELLOW)
Editor’s note: For further reference, consult Building Construction for the Fire Service, Third Edition (BCFS3). Page numbers, where applicable, are included after the caption.
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Heavy wood firestopping was removed to install a standpipe main requested by the fire department. The Fire Department of New York, which developed standpipe operations, finds it is faster to stretch directly to the third floor instead of using the standpipe Here, the firestopping was not replaced because the gypsum board ceiling was installed right after I took this picture. A void fire would spread throughout the voids, following the fire main.
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Fire would spread from floor to floor through the piping holes. The collapse hazard may drive firefighters from the building, especially if the floors are of truss construction. You did not lose the building—the construction techniques used, which made it deadly for firefighters to remain in the building, destroyed it. It is a combustible building, a type that can be destroyed easily by fire.
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Flat-roof buildings require a pitch to drain off water. The light-colored wood color strips are battens that provide the pitch. They also make it possible for fire to spread rapidly over the plywood surface.
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I found this “firestopping” situation using wooden I-beam scrap on both the East and the West Coasts. According to a building inspector (who had also been a carpenter), “We always used to cut off ends of joists for firestopping. You can’t ask a builder to cut up good wood for firestopping, can you?”
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This building has two occupancies. The term “demising walls” indicates a wall between two occupancies, which often means a degree of resistance to fire passage. Let’s look at the wall.
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Note the unprotected steel girder supporting the lightweight wood trusses. Sheets of unsupported gypsum wallboard are “buttered” into place above the beam between the trusses. With any serious volume of fire, fire operations at this building should be defensive. Use your thermal imaging camera (i.e., the firefighter’s radar) to check for overhead fire. If there is any fire, go defensive immediately. The time to failure is unpredictable.
Additional information on the hazards of wood construction can be found in Chapter 3, pages 89-142, and Chapter 12, pages 518-563, of BCFS3 and are updated in Ol’ Professor (Fire Engineering) and available on FireEngineering.com.
FRANCIS L. BRANNIGAN, SFPE (Fellow), the recipient of Fire Engineering’s first Lifetime Achievement Award, has devoted more than half of his 62-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.
