Naturally rot-resistant wood is wonderful stuff, but as human pressure on forests increases, woods have become more and more expensive, forcing people to search for more cost effective alternatives. A popular substitute, especially in areas far from cedar and redwood forests, is decking made from less rot-resistant, cheaper softwoods that are pressure-treated with various chemicals that inhibit decay.
The degree of a wood’s rot-resistance depends upon the depth of treatment—wood that is in contact with damp soil needs the deepest treatment. Treated decking can be finished with stains and paints much like natural wood (with some adaptation), and it retains all the strength of natural wood.
Pentachlorophenol, creosote, and chromated copper arsenate (CCA) were once the standard wood preservatives. All of these are extremely toxic. Somewhat less poisonous treatments, such as amine copper quat (ACQ) and copper azone (CA), are starting to replace them for residential use. However, the safer alternatives are still far from benign.
ACQ- and CA-treated wood cannot be recycled or burnt—it’s toxic to produce, work with, and dispose of.
Even if your deck is made of natural wood, most finishes designed to keep its appearance fresh and to retard decay are bad for the environment and for you.
Also, look for low-VOC, low-toxicity finishes made by such companies as AFM Safecoat, Bioshield, or Eco Safety, among others.
