Engineered wood I-joists, fabricated from laminated veneer lumber (LVL) flanges and oriented strand board (OSB) webs, offer many advantages over solid sawn lumber joists in residential and light commercial construction. With the expanded use of these products has come an increasing need to be able to treat them with biocides to prevent attack from decay fungi and termites during service. Historically, the only ways to treat engineered wood I-joists were either by treatments of the individual components during their manufacturing processes or by a post-manufacture treatment of the fabricated joists using a solvent-based pressure/vacuum process. These historic methods had disadvantages and were not commercially favorable. A novel chemically-based technology was developed in 2004 for the rapid treatment of solid wood substrates in a waterborne carrier. This treatment process, based on patented buffered amine oxide technology, has enjoyed widespread commercial success for solid wood substrates and is now being used to treat engineered wood components as well. Results presented in this paper indicate that this new technology can successfully penetrate the LVL and OSB components of manufactured I-joists with appropriate amounts of fungicides and insecticides at full penetration, enabling the treated I-joists to successfully resist decay and termite attack in-service. Although the treatment process uses water as its carrier, it does not significantly impair key mechanical and physical properties of the engineered wood I-joists. A major U.S. manufacturer of engineered wood I-joists has found that, with proper control of the treatment process, there was no need for a reduction in the design values of their I-joist products. The Buffered Amine Oxide Treatment System (known commercially as the TRU-CORE Technology) was introduced commercially in Australia in 2011 for the biocide treatment of engineered wood I-joists. Commercial introduction in the U.S. is scheduled for early 2012.

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