Choosing Safe Lumber
(Page 2 of 3)
February/March 2003
By Lynn Keiley
When building decks or similar projects, you can protect your investment by using a design that incorporates stone or concrete footings to support wooden members, which would otherwise rest in the ground where moisture and decay-causing microorganisms lurk.
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Recycled-Plastic Lumber. Many of the plastic milk bottles, detergent containers and grocery bags we recycle are being mixed with wood fiber to make a new generation of decking material called composite lumber. This recycled plastic lumber is now available in many home-improvement stores, including The Home Depot and Lowe's.
These products last as long as CCA-treated wood. Unfortunately they cost up to 80 percent more. Manufacturers, however, say the increased cost is offset because the composite lumber doesn't need the periodic staining and sealing that traditional wood requires. Composite lum ber can be twice as heavy as many softwoods, so be sure your design allows for the extra weight. Recycled-plastic lumber is not strong enough to use for structural members, such as load-bearing walls, deck frames or floor joists, so you'll need to use traditional wood for those areas.
Composites are a great choice for any surface where you or your children are likely to make skin contact, particularly decking, rails and outdoor tables. These products also are much easier to clean than wood, and you don't have to worry about getting splinters in your hands or feet. You also can use recycled-plastic lumber in the garden, since it contains no arsenic or chromium to contaminate the soil.
New Chemical Treatments. The wood industry has come up with a few arsenic-free wood treatments to replace CCA. Two common alternatives are known as Preserve ( www.treatedwood.com ) and Wolmanized Natural select ( www.naturalselect.com ) lumbers. Preserve's preservative is alkaline copper quaternary, or ACQ. Natural Select uses copper azole as its preservative. Both brands rely on copper as their primary fungicide; the quaternary protects against termites and other fungi that tolerate copper. Both Preserve and Natural Select protect wood as well as CCA-treated wood, yet are far less toxic to humans, making them a good choice in areas where other alternatives aren't practical — structural support members or deck pilings, for example. These are chemical preservatives though, and the copper they contain could be toxic to earthworms and other beneficial soil microbes, so they shouldn't be used in the garden. Expect to pay 15 percent to 30 percent more for these alternatives than you would for CCA-treated wood.
Borates. In cases where the wood will not be exposed to the soil or water, borates, a form of naturally occurring salt, will help prevent decay from fungi and wood-boring insects such as carpenter ants and termites. Considered very low in toxicity, borates are easily applied in liquid form using a standard sprayer. Borates are water soluble, so they will leach from wood that's exposed to water. Restrict their use to protected projects.
