Lightweight Truss

Special Blog post by:

Azarang (Ozzie) Mirkhah, P.E., EFO, CBO

On December 4, 2006, International Association of Fire Chiefs (IAFC) issued a “Member Alert” notifying their membership about the hazards associated with the light-weight construction in residential occupancies. In that Member Alert titled “Caution Urged with Composite Floors” it was stated:

“There have been several cases of firefighters falling through floors made of composite structural components and an even greater number of near-miss situations. This type of construction is being investigated as a contributing factor in a line-of-duty death. There is a proliferation of engineered floor systems in residential occupancies across the United States. Many newer residential occupancies incorporate lightweight, engineered wood or composite structural components, including trusses, wooden I-beams and lightweight flooring systems. In most cases, these systems are structurally sound and designed to support the appropriate loads under normal conditions; however, they are likely to fail very quickly under fire conditions.

These components and systems are most often found in situations where applicable codes do not require any rated fire resistance between floor levels. They have much less inherent fire resistance than conventional wood joist floor systems and conventional wood decking. Remember – many codes do not require any fire resistance in residential floors! In the several cases of firefighters falling through floors, those floors had been exposed to fire from below for relatively short periods.”

Then, on October 1, 2007, [click to continue…]

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