When copper chromated arsenate (CCA) was eased off the market at the end of 2003 due to fears about its toxicity, builders needed to find new sources for rot-resistant structural lumber. As contributing editor Scott Gibson has discovered, the industry has responded by developing three new types of rot-resistant framing materials. The new materials include lumber treated with alkaline copper quaternary (ACQ) or copper azole (CA); wood treated with borate, a naturally occurring mineral salt; or fiberglass-reinforced plastic lumber (FRPL), made from recycled plastics. The article includes a sidebar about new compounds and organic treatments in development.
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