PREPLANNING BUILDING HAZARDS
Editor`s note: For further reference, consult Building Construction for the Fire Service, Third Edition.
(Top right) Leaking roofs are a major problem in the maintenance of buildings. One solution is to add a whole new roof. This is also done to make a roof line more aesthetically attractive. Whatever the reason, ventilating the second roof is no help in a fire in the contents. How do we know this is a second roof?
(Middle right) We “undress the building.” Alert New Smyrna Beach, Florida, firefighters noticed the alteration. The old tar and gravel built-up roof is still in place. Note the front of the new truss roof is cantilevered out. The balance point is just above the left-hand side of the side windows.1 (Ref. p. 554)
(Bottom right) In general, all illustrations should be easily understood on sight; however, very hazardous conditions are not always easily apparent. This illustration requires careful attention. Look for patch-up jobs in old buildings. This old three-story building in Alexandria, Virginia, shows a patched-up wooden girder (a beam that supports other beams). What is the purpose of that fancy-looking plate in the center of the beam? Look closely above the plate on the top of the girder (center of photo). A vertical steel rod is barely visible. This rod extends to a girder or truss in the cockloft, extending from side wall to side wall. The effect of this rod is to divide the girder into two parts, making it possible to carry a much heavier load. (Ref. p. 55) It is the equivalent of putting a post under the girder at the same point. A “roof fire” could cause the connection of the rod to the girder up in the cockloft to fail, causing the girder supporting the second floor to be overloaded and fail.
(Below) This brickwork is badly deteriorated. Mortar (probably sand lime, rather than Portland cement) has washed out of the joints. This wall has no integrity and is a candidate for collapse, particularly if it receives a lateral blow such as from a falling floor. (Ref. p. 157)
Reference
1. Harlow, David T. “New Roofs Over Old.” Fire Engineering, November, 1987. For a copy, send a self-addressed business-size envelope with 55 cents postage to me at 2041 Daylily Road, Port Republic, MD 20676.
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FRANCIS L. BRANNIGAN, SFPE, a 52-year veteran of the fire service, began his fire service career as a naval firefighting officer in World War II. He`s best known for his seminars and writing on firefighter safety and for his book Building Construction for the Fire Service, Third Edition, published by the National Fire Protection Association. Brannigan is an editorial advisory board member of Fire Engineering.
