The record wildfires of 2020 have sparked significant interest in fire-retardant-treated wood products.
Visits to the FireResistantWood.org website nearly doubled last year, as people turned to the web to find out more about fire retardants. The website is maintained by Western Wood Preservers Institute (WWPI), which represents treaters in the West who produced fire-retardant-treated wood.
The increased interest in the products also underscored some common misperceptions about fire-retardant-treated wood. One common question: “Can preservative-treated wood also be fire-retardant treated?” While there are fire retardants rated for exterior use, it is not possible to treat wood with both preservatives and fire retardants.
Traditionally, most fire-retardant-treated lumber and plywood is treated for interior use, where building codes define where this wood can be used as an alternative to non-combustible materials. Building codes also are very specific on what qualifies as fire-retardant-treated wood.
The International Building Code, Section 2303.2, defines fire-retardant-treated wood as “wood products impregnated with chemicals by a pressure process.” If not applied through pressure, the treatment “shall be an integral part of the manufacturing process of the wood product.” The 2018 edition of the IBC further clarifies what is allowed: “The use of paints, coatings, stains or other surface treatments are not an approved method of protection as required in this section.”
Still, the wildfires have spawned promotion of a variety of spray-on coatings claiming to work just as well as fire-retardant-treated wood. The effectiveness of these products remain unproven, yet are promoted for application on existing wood for protection. By comparison, fire-retardant-treated wood has been used for decades, creating an extensive history of performance in a variety of structures.
Another common misperception is that fire-retardant treating makes the wood fireproof. The reality is that fire retardants are intended to slow the spread of fire so that occupants of the structure can safely exit and first responders have more time to try to save the structure.
The intensity of today’s wildfires takes a toll on every material. Fueled by high winds, the fast-moving wildfires can melt automobiles and crack pavement and concrete. Wood, even when treated with fire retardants, has little chance to withstand such infernos.
The complexities of the wildfire issue defy simple solutions. Protecting structures from the ravages of wildfire will take a multi-faceted approach, which will likely include fire-retardant-treated wood.