Treated Wood in Transition
Alternative wood treatments can be less toxic for the environment and humans.
By Tristan Roberts
Wood Treatment Products Inc.
The treated-wood industry is in the midst of major changes
today. The leading treated-wood product, chromated copper arsenate (CCA), was
taken off the market for many uses at the beginning of 2004. The mainstream,
copper-based replacements for CCA corrode fasteners more rapidly than CCA,
increasing the risk of collapse for thousands of decks and other structures.
Some of the new chemical treatment systems are entering the market with very
little scrutiny from regulators, while one of the most promising treatment
alternatives, TimberSIL, is the target of a campaign by the industry to get
regulators to reclassify it as a toxic chemical—even though it isn’t toxic. And
meanwhile, the 60 billion board feet of CCA-treated lumber that’s been put in
service over the past 40 years is getting old; huge quantities are coming out
of service and being disposed of, posing an environmental nightmare.
Wood is a natural resource, and there is much to be said for
increasing its durability. In North America, we produce roughly 39 billion
board feet of softwood lumber per year, of which roughly 8.4 billion board feet
are being treated for outdoor decks and other uses. Treating softwood lumber
with preservatives can make the difference between complete disintegration
within months, in the worst conditions, and the same wood lasting decades,
saving billions of board feet over time. The challenge is to gain this benefit
in a way that doesn’t replace one environmental concern—cutting down trees—with
others, such as heavy-metal pollution and toxic leachate from landfills.
There is much to consider among the various treated-wood
alternatives. This article examines the world of protected and preserved wood:
positive trends, growing concerns about disposal and toxins, and both promising
and troubling materials entering the market. Two conventional wood
preservatives, pentachlorophenol (“penta,” or PCP) and creosote, are outside
the scope of this article, though it is worth noting that despite
well-documented health risks and environmental problems with both, each still
represents 10 percent of all treated-wood volume in North America, including
some nonresidential building applications.
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