ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, September 8, 1996 TAG: 9609100005
SECTION: HOMES PAGE: 3 EDITION: METRO
SOURCE: GENE AUSTIN KNIGHT-RIDDER NEWSPAPERS
Pressure-treated wood is an extremely useful product for do-it-yourselfers planning outdoor construction, but if it is not selected and used properly, it can also be hazardous and result in failed projects.
The wood, which is usually southern yellow pine treated with preservatives that are forced into the fibers under high pressure, is highly resistant to rot and insect attacks. That makes it valuable for such uses as fence posts, landscaping timbers, deck supports and decking, outdoor furniture, planters and many other outdoor uses where untreated wood could fail in a few years. The wood generally has a light-green or tan color.
In addition to regular lumber and timbers, pressure treating is also used in the manufacture of marine plywood and some shaped products such as decorative deck posts, railings and moldings.
The biggest asset of treated wood is that, if treated to the proper level, it will resist rot even if used in contact with the ground. Any wood that will touch the ground, such as a fence post, deck post or garden border, should have a treatment-retention level of 0.40. The retention level should be included in the ``quality mark'' stamped on the wood, or on a tag stapled to the end. Treated wood with a retention level of 0.25 should be used above ground only.
But the easy availability of pressure-treated wood, and the widespread advertising given it, might lull some do-it-yourselfers into overlooking the hazards. Most pressure-treated wood contains chromated copper arsenate, or CCA, a compound that includes arsenic.
Pressure-treated wood appears to be hazardous mostly when misused. The Environmental Protection Agency has issued some basic rules that are worth reviewing:
Wear a dust mask and goggles when sawing, sanding, drilling or otherwise machining pressure-treated wood. This is especially important when power tools are used, since they raise more sawdust and splinters than hand tools. It's best to do any machining of the wood outdoors.
Wash skin thoroughly after contact with treated wood. Always wash before eating, drinking or using tobacco products.
Wash clothing, separately from other clothes, after machining treated wood.
Never dispose of treated-wood scraps by burning them - the vapors are toxic. Dispose of scraps by putting them in the trash or by burying them.
The EPA also specifies that treated wood not be used where it can affect human or animal food, including food-storage containers, cutting boards, countertops and beehives. It should also not be used where it could come into contact with drinking water.
My own basic rule is not to use treated wood where untreated wood will do. In general, I would not use treated wood indoors unless it would be exposed to moisture or termites might be a problem.
Additional tips on buying and using treated wood:
Some of the treated wood sold at home centers and lumberyards is waterlogged. A tip-off, in addition to the damp feel of the wood, is its extreme weight. For fewest problems after construction, look for wood that is dry, straight and free of cracks.
If a ``natural'' appearance is wanted, treated wood should be coated with a water-repellent sealer to help prevent warping, splitting and mildew. Periodic sealing is especially important when the wood is used for decks, gazebos and other construction where appearance is important.
Treated wood can also be painted or stained, but the wood should be thoroughly dry before paint or stain is applied. Test paint or stain on an inconspicuous area to make sure the wood is dry enough to give good results. Oil-based paints and semi-transparent, oil-based stains work best on treated wood.
The American Wood Preservers Institute, a trade group in Vienna, Va., says treated wood can safety be used for garden borders, including raised beds for vegetables and flowers. Other safe garden uses, according to the institute, are tomato stakes, mushroom trays, compost bins and vineyard supports.
LENGTH: Medium: 82 linesby CNB