Firefighter Safety Report: Truss System Failures
NIOSH | John Howard M.D.
• Use extreme caution when operating on or under truss systems.
• Notify the incident commander whenever truss construction is discovered.
• Communicate interior conditions to the incident commander as soon as possible and provide regular updates.
• Use a defensive fire-fighting strategy once burning of truss members is identified (unless someone is trapped).
• Expect imminent collapse once lightweight truss roofs or floors are involved in a fire [Klaene and Sanders 2000].
• If possible, avoid cutting the truss chords when cutting holes for roof ventilation. Cuts can weaken the roof.
• Avoid roof areas loaded by air conditioning units, air handlers, and other heavy objects.
• Be aware of alternative exit routes at all times when working above or below a truss.
• Consider using roof ladders or working from aerial ladders or platforms instead of walking or standing directly on the roof [Brannigan 1999; Dunn 1998].
• Immediately open ceilings and other concealed spaces whenever a fire is suspected in a truss system.
• Be aware that fires can be in the truss void or other concealed areas (see Figure 2). Once the fire enters a concealed space, it can travel to remote locations rapidly, since the wooden web members surrounded by open air space provide an excellent fuel source [Brannigan 1999].
• When a truss is suspected to be above a ceiling, use a pike pole or other tools to open up the ceiling and check for truss construction [Brannigan 1999]. If there is a fire barrier in the void, use the same procedure on the opposite side.
• Be aware of the possibility of flashover or back draft when opening concealed spaces and take the appropriate safety precautions.
• When opening ceilings or other concealed spaces, have charged hose line(s) ready.
• Be aware of the nearest exit and of other fire fighters in the area. The incident commander must consider and provide for alternative exit routes from all locations where fire fighters are operating [Klaene and Sanders 2000].
• Understand that fire ratings may not be truly representative of real-time fire conditions.