Engineered wood appeared in the 1970’s as a lighter, more precise and easier to install alternative to traditional lumber. However, over the course of 20 years, firefighters associations began to raise concerns over the use of this type of construction material in one and two family dwellings. Multifamily construction using engineered wood wasn’t as much of an issue because of the stricter fire prevention guidelines, which included the installation of sprinklers and other safety features. For single and two-family homes, engineered wood performance isn’t the problem. It’s what happens to the material during a fire.
The amount of time an engineered wood floor can withstand fire below the floor structure is the real problem. Firefighter fatalities led to UL testing and it was confirmed that wood I-beam constructions could collapse in as little as six minutes. Unfortunately, not enough time for firefighters to get into the house and rescue people inside, which creates an extremely dangerous situation for the firefighters doing an assessment of the building. The photos of these tests clearly show how the OSB material charred and quickly burned out of the I-Beam, leaving only the flanges to support the weight and stress above the fire, which quickly let to floor collapse.
Safety standards were quickly established. They required engineered wood floor constructions to resist more than 15 minutes during a fire. The latest ICC-ES fire certification standard is continually being revised and updated.
The ICC-ES standard identifies different methods to add fire retardant material (such as treated gypsum). Namely, below the floor structure or attached to the OSB structure of the wood I-beams. Floor-truss constructions, with their metal plates, also require sheathing. Some manufacturers have also begun to offer I-beam constructions with sprayed-on chemical retardant.
Open-Joist TRIFORCE® exceeds the standards
Safety for the homeowner and fire and rescue personnel is one of our primary concerns. Open Joist TRIFORCE wood construction exceeds ICC-ES standards. Furthermore, it only requires sheathing the 24’’ OSB End Panel with gypsum board or wood structural panel. The open joist triangular web area requires no additional fire protection.
Find out more about Open-Joist TRIFORCE fire resistance rating.