Pressure treating wood with waterborne preservatives is done to counteract the harmful effects insects, microorganisms and fungal decay can have on wood. But as of Jan. 1, chromated copper arsenate- (CCA-) treated wood voluntarily has been removed by wood producers from the consumer market in the United States and Canada. The bastion of the treated wood industry since its development in 1933, CCA has joined the ranks of products deemed environmentally incorrect by agencies such as the U.S. Environmental Protection Agency (EPA).
The replacements to CCA soon will become familiar by their acronyms. The most commonly used alternative waterborne preservatives are alkaline copper quatenaries (ACQ-C and ACQ-D with carbonate), sodium borates (SBX) and copper azoles (CBA-A and CA-B). There are some lesser used waterborne chemicals, such as ammonial copper zinc arsenate (ACZA), and variations of the previously mentioned compounds. Naturally weathering wood alternatives such as redwood, yellow cypress and certain cedars are environmentally acceptable but more expensive than CCA-treated wood.
The consumer market generally uses treated lumber for decks, outdoor furniture, gazebos, fences, railings, landscaping, and park and playground equipment. The roofing industry's primary contact with pressure-treated lumber is for wood blocking, curbs, sleepers, batten strips and other integrated locations where a fastening substrate is needed.