Building officials are the gatekeepers to building construction. To approve any construction, including where wood is the principal product, they need to know a lot of information. The American Wood Council aims to make the job of building code official a little easier when it comes to knowing about wood products and the latest wood-related code provisions.
One of the vehicles we use to accomplish that goal is a free membership program for qualified code officials called Code Official Connections. A benefit of that program is an e-newsletter called WoodPost, written specifically for U.S. building and fire code officials. WoodPost is published every other week and contains the most up-to-date building code related wood design and construction information, along with technical support for use of traditional and engineered wood products. Following are two recent examples of the type of information we regularly communicate to code officials.
Fire-Retardant-Treated Wood and Alternative Methods
Fire-retardant-treated wood (FRTW), by definition, is impregnated with chemicals either by a pressure process or by other means during manufacture. During the last code cycle, it was clarified in the 2018 International Building Code (IBC) that "other means during manufacture" requires the impregnation of chemicals into the wood during the manufacturing process in order to meet the definition of FRTW in the code. However, as in the past, surface-coated products intended for use where FRTW is permitted can be approved by the code official by alternative materials and methods provisions, IBC Section 104.11, and with the help of evaluation reports. The International Code Council Evaluation Service (ICC-ES) has developed several Acceptance Criteria (AC) documents for their evaluation which address surface burning characteristics of the product, durability of the treatment, corrosivity, the effects of the treatment on the strength or stiffness of the wood substrate, and additional considerations specific to the product's end use. Code officials can comfortably accept these alternative-to-FRTW products for use based on evaluation reports referencing these acceptance criteria, which then also specify the conditions of their use.
Using Correctly-Sized Nails—Common and Box
The International Residential Code (IRC) provides a table for fastener use (Table R602.3(1)) that has been greatly improved in the 2015 edition to include both common and box nail alternatives for each building connection. The updated table shows the minimum nail dimensions for each (length and diameter) and the number of nails required depends on the type of nail used—common, box, or other. For sheathing applications, nail head size is either prescribed directly or associated with the specified nail type. For example, an 8d common nail (2.5” x 0.131”) prescribed for roof sheathing attachment has a standard head diameter of 0.281”. Nails with reduced dimensions compared to those required in the table should be rejected when inspected for compliance with the IRC conventional construction provisions. Evaluation reports can be used to determine the proper substitution of proprietary power-driven nails. These substitute nails may have varying diameter, length, and head style (i.e. clipped, offset, oval, or notched) and varying number required per connection.
The AWC National Design Specification® for Wood Construction (AWC-NDS®) contains Appendix L showing standardized dimensions for common and box nails, including the head diameter, based on requirements in ASTM F1667, Standard Specification for Driven Fasteners: Nails, Spikes, and Staples.
If you have a relationship with your local building or fire official, and you think they might benefit from this type of information, please do share information about the AWC program with them at: www.awc.org/codeconnections.