Why Fire Rated?
Rationale for Fire Rated, Coated I-joists
When joists were first introduced to the Housing Industry some 50 years ago, the benefits were very quickly recognized. They were far more consistent dimensionally than solid sawn 2x10’s and 2x12’s and their superior physical properties allowed for longer spans. Many of the teleposts in the basements of residential housing could be eliminated. Joists were not subject to shrinking because the OSB web contains very little moisture, and this eliminated the squeaking, so common with solid sawn lumber floors.
However, it did not take long to discover one significant weakness. In the event of a fire, the OSB web would burn through in approximately 5 minutes versus approximately 15 minutes for a 2x10. At that point, the floor was subject to failure, as it was no longer capable of carrying a load. This meant that homeowners had less time to evacuate a burning dwelling, and first responders would crash through floors if they arrive at burning residence more than 5 or 6 minutes after the start of a basement fire, and entered the burning house to perform a rescue. For this reason, first responders lobbied to mandate improvement in the performance of joists in the event of a fire.
However, there are other benefits of coating joists with intumescent paint. This coating makes it very difficult to ignite the joists, thereby reducing the likelihood of a fire starting in the basement floor. Also, intumescent paints (like most paints) contain fungicides, which help suppress the potential for mold and mildew. This means that joists are not as susceptible to degradation on job sites, or in outdoor storage at the lumber yards.
Finally, it is far less expensive to coat joists with intumescent paint, than the alternative of sprinklers, or completely dry walling the basement.
2013 Fire Losses, United States
According to the National Fire Protection Association:
- 369,500 house fires occurred in the U.S. during 2013
- 3,240 civilian fire fatalities
- 15,925 civilian fire injuries
- $11.5 billion in property damage
Source: "Fire Loss in the United States during 2013", National Fire Protection Association.
Note: The photos are from Edmonton Sun, 2007
2007 Fire Losses, Canada
According to the Council of Canadian Fire Marshals and Fire Commissioners:
- 42,753 fires occurred in Canada during 2007
- 224 civilian deaths
- 2 firefighter deaths
- $1.6 billion in direct property damage
Source: "Fire Losses in Canada. Year 2007 and Selected Years", The Council of Canadian Fire Marshals and Fire Commissioners.