PREPLANNING BUILDING HAZARDS
FRANCIS L. BRANNIGAN
Editor`s note: For further reference, consult Building Construction for the Fire Service, Third Edition. Page numbers are included after each caption for your convenience.
(Top right) Many old houses like this one are being converted into bed and breakfast inns. They may have a large number of occupants, most totally unfamiliar with the sometime peculiarities of the exit facilities–for example, up a couple of stair steps, down a hall, and out to a fire escape. A common problem in these structures is interconnected voids in which fire can grow and be well advanced by the time a detector picks up smoke and sounds an alarm. Section 5-1.3.4 of the National Fire Alarm Code (NFPA 72) requires detection devices in certain combustible concealed void spaces (such as attics) when “total coverage” is required in other codes such as the Life Safety Code® (NFPA 101). When was the last time you saw a building with detection devices in these areas?
(Middle right) This bed and breakfast inn is sprinklered–but with a 13R partial sprinkler system that covers the principal occupied areas but not the voids. The concept is to suppress or control a contents fire so the occupants can escape before flashover occurs. The system has been successful a significant number of times. If, however, the fire starts in the void or extends into it before the sprinklers suppress the fire, there is a very serious problem. Some years ago, four Syracuse, New York, firefighters died in a residence that was converted into a rooming house for students. Sprinklers were provided only in the corridors.1
It is a good bet that a well-established fire in the voids will destroy the building. The incident commander has no good guidance for determining whether the sprinklers should be shut off or kept operating if they are not hitting the fire. At times, the water can be scalding. “Expert witnesses” testifying during a trial can criticize whichever action is taken. Immediately after the fire, it is best to document exactly what was done and the detailed reasons for doing it. (Ref. p. 578)
(Inset, bottom right) This wooden restaurant in Fort Worth, Texas, does not appear to present any special hazard of collapse. However….
(Bottom right) Inside we see a cold drawn steel cable tying two sides of the building together. This is a sign the building was experiencing structural trouble, which was remedied by tying the walls together. Cold drawn steel, such as this or any other cable or the tendons in prestressed concrete, totally loses its tensile strength at 800°F, less than the temperature in a self-cleaning oven.
If fire causes this cable to slack off, whatever defect it was remedying is now back in effect. The defect may be serious enough to cause collapse. Structural repairs to buildings are made for serious reasons; failure of the repair system is a serious problem. ( Ref. pp. 33, 314)
References
1. Demers, D. “Four Firefighters Die in Syracuse Fire,” Fire Command, Oct. 1987, 20.
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.
