Code Definitions Are Important, SBCA Helps on FRTW
During Structural Committee review at the 2019 ICC Group B Committee Action Hearings, back in April 2019, the committee considered code change G10-19. This change proposed altering the definition of “Treated wood” in Section 202 of the International Building Code (IBC).
According to SBCA technical staff member Larry Wainright, there was a lot of testimony on the merits of changing the definition of treated wood. “While listening to the discussion, I was confused because I could not recall any code language that referred to ‘treated wood’ generically,” says Larry. “I did a quick search on the term and found that it does not exist. So I got up and testified to that effect. That pretty much ended the discussion and the item was disapproved.”
Officially, the Structural Committee disapproved the code change because they didn’t feel it improved upon the current definition and could cause confusion.
SBCA's Topical Library: Fire Protection - Fire Resistance Rated Truss Assemblies.
At the ICC Final Action Hearings on October 24, arguments for a new definition of “treated wood” were presented to those in attendance and the committee action for disapproval was overturned. According to Larry, this was a positive outcome for everyone. “They deleted the definition altogether and modified what was two sub-definitions for FRTW and preservative treated lumber. The new revised definitions make it clear the FRTW is defined as pressure impregnated lumber as was already defined in Section 2304,” says Larry. “This was always the intent of the code and this just cleans up the outdated reference and clarifies the intent.” The new code language, if approved, would read as follows:
Section 202 of the 2018 International Building Code
Delete without substitution:
[BS]TREATED WOOD. Wood products that are conditioned to enhance fire-retardant or preservative properties. [BS]TREATED WOOD. Wood products that are conditioned to enhance fire-retardant or preservative properties. [BS]TREATED WOOD. Wood products that are conditioned to enhance fire-retardant or preservative properties.
Add new definition as follows:
FIRE-RETARDANT-TREATED WOOD. Wood products that, when impregnated with chemicals by a pressure process or other means during manufacture, exhibit reduced surface-burning characteristics and resist propagation of fire.
PRESERVATIVE-TREATED WOOD. Wood products that, when impregnated with chemicals by a pressure process or other means during manufacture, exhibit reduced susceptibility to damage by fungi, insects or marine borers.
It is interesting to note that the American Wood Council (AWC) is directing voters to disapprove this definition change:
|Code Change||Recommended Government Online Consensus Vote (cdpACCESS)||Summary|
|G10-19||Disapprove||Use of the word "impregnated" in the proposed new definition for treated wood in Public Comment 2 could be interpreted to prohibit some preservative treatments that are not applied through impregnation, such as field-applied preservatives used to treat cut surfaces and drilled holes in preservative-treated wood. These field-applied preservations are approved under the AWPA U1 standard and meet the requirements of Chapter 23 for preservative treated wood. This conflicting definition and the Chapter 23 requirements could cause difficulty for builders and code officials in regard to these approved applications.|
However, it's very important to note the new code change does not prohibit the use of topical coatings. It only requires that topical coatings go through the alternative materials process to show equivalency by obtaining an evaluation report for their product. This code change addresses the larger problem, which is confusion over the term ‘treated wood,’ by providing clearer definitions for fire-retardant-treated and preservative-treated wood. SBCA strives for greater clarity in the code and does not see a substantive reason for this code change to be disapproved.
For more information on SBCA’s involvement with fire treated lumber, please review the following links:
- CMs' Best Interests Protected at ICC Hearing
- Wood Walls Framed for Fire
- Non-FRTW Trusses Comply with IBC in Type III Construction
- A Designer’s Guide to FRTW
- A Designer’s Guide to PTW