Fire-Retardant Treated Wood
by Katrina Reed, on Apr 20, 2020 12:00:00 AM
Q: Is fire-retardant-treated wood permitted in a healthcare occupancy for roof construction, including girders and trusses, in Type II (000) construction? Background: NFPA 101-2012 Section 126.96.36.199 and 188.8.131.52 allows FRTW for certain Type I and II construction but does not mention Type II (000). NFPA 220-2012 Section 184.108.40.206.2 indicates FRTW is allowed in Type II buildings.
A: This issue of fire-retardant treated wood used in Type I and Type II construction can be confusing and is often misunderstood.
Starting with section 220.127.116.11 of the 2012 Life Safety Code, it says Type I (442), Type I (322), Type II (222), or Type II (111) shall be allowed to have a roof/ceiling assembly constructed with fire-retardant-treated wood meeting the requirements of NFPA 220. But it specifically does not include Type II (000) construction. Why? Some may say because Type II (000) construction does not require any fire-ratings, which is true. But being Type II, it does require non-combustible or limited-combustible materials for structural support, and fire-retardant-treated wood is considered to be a combustible material. So that alone seems to be conflicting.
But section 18.104.22.168 of the 2012 LSC does say NFPA 220 shall be used to determine the requirements for construction classification. That means whatever NFPA 220-2012 says, it is endorsed by the 2012 Life Safety Code. And section 22.214.171.124.2 of NFPA 220-2012 says fire-retardant-treated wood shall be permitted for roof construction, including girders and trusses, in Type II buildings. That includes Type II (000) construction.
So, the answer is yes. Fire-retardant-treated wood may be used in roof supports for Type II (000) construction.