Dear Dr. Moore: I love the look of a wood deck, but I need something that resists moisture and termites. Is treated wood safe?
Yes, absolutely. There are a number of treated wood products that are highly effective at resisting bugs, mold and rot — and are also safe in terms of human health and the environment.
Over the last few years, there has been some concern about lumber treated with CCA (chromated copper arsenate). CCA has been used successfully for decades. But, because it contains arsenic, people began to question whether small amounts could leach out of the wood and cause harm. As a result of this concern (and please note that the science itself is inconclusive), CCA is no longer available for residential use.
In its place are a number of alternatives, but the most popular are ACQ (alkaline copper quat), CBA (copper azole) and SBX (sodium borate) — all approved by the U.S. Environmental Protection Agency (EPA).
For outdoor use, ACQ and CBA are recommended, as borate becomes less effective when repeatedly exposed to water.
However, if you’re building the deck yourself, note that ACQ and CBA are corrosive to metal. Make sure to use galvanized or stainless steel nails, fasteners and connectors, so they won’t rust and pose a safety hazard over time.
For those who have used CCA lumber in the past, there’s no cause for alarm. The EPA sees no reason to replace existing structures — including decks and playground equipment. The phase-out of CCA was a precautionary measure, taken voluntarily by the wood treating industry.
If you’re concerned about exposure, the EPA suggests applying a penetrating coating, such as a semitransparent stain, on a regular basis.
As a sensible environmentalist, I agree that reducing the use of arsenic is a reasonable precaution — and I’m glad the wood treating industry has taken the initiative and provided other options.
I prefer wood over alternatives, such as plastic and steel, because it’s renewable and sustainable over the long term. It also requires less energy to produce and results in fewer greenhouse gas emissions.
(Questions may be sent to Dr. Moore at the following e-mail address: Patrick@SensibleEnvironmentalist.com.)
