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News Flash!
Pressure treated lumber has been around along time. It's used for decks, playgrounds, retaining walls, utility poles, railroad ties and many other structural uses. Wood is treated with chemicals to help it resist rot, decay and insects, especially when it is exposed to moisture. For years the bulk of the treated lumber on the market was treated with CCA, chromated copper arsenate.
In February 2002, after years of research of the potential hazard of the arsenate leaching out of the wood and into the ground, and possibly making its way into our ground water and gardens, the EPA announced a voluntary joint decision by the manufactures of CCA to phase out the production of arsenic-containing treated wood products by December 31, 2003. Wood treated prior to this date could still be used. Contractors with inventories of CCA-treated lumber are permitted to use the wood after this date until they use up their inventories. Previously built structures with CCA-treated lumber are not affected by this action.
You will not find anymore CCA-treated wood products at your local home center or lumberyard, but you will find several alternatives.
Ammoniacal Copper Quat (ACQ-Types A, B, and C) - Wood treated using this preservative is marked under the brand name ACQ Preserve by Chemical Specialists, Inc. or CSI.
Amine Copper Quat (ACQ-D) - Similar ingredients to ACQ-A but uses ethanolamine instead of ammonia to act as the treating solution carrier. Lumber treated with this preservative is marketed as NatureWood.
(Collectively, all the ACQ products are sometimes referred to as copper quat preservatives)
Copper Azole-Type A (CBA-A) - Another new generation wood preservative that contains copper and boron. Often referred to as Wolmanized Natural Select.
Borate Oxide (SBX) - A class of wood preservatives that contain boron as the active ingredient. Borate compounds include sodium octaborate, sodium tetaborate, sodium pentaborate and boric acid. Confused yet? Well, ya' see, it's like this...borate oxide preservatives are water-soluble and do leach. Therefore they are not recommended for wood in soil or constant water contact. Some of the brand names of these types of wood products are Advance Guard and Smart Guard.
Naturally Durable Wood such as redwood, cedar, locust, and others derive their durability from naturally occurring chemicals deposited in the tree during their life cycle. These chemicals become more concentrated as the tree ages and are only found in the heartwood, or center of the tree or log. These naturally occurring chemicals are collectively called extractives. They are water-soluble so they and their decay resistance will leach out over time.
Non-Wood Options consist of plastic and recycled plastic lumber as well as recycled wood/plastic composite. They have a low moisture absorption rate and are fairly resistant to decay, insects and sun damage. They contain no toxic chemicals as is in treated wood lumber products. These products can be worked and installed just like regular wood, but because there is no grain, pre-drilling is not required for self-drilling screws. These products also weigh more than standard treated products.
The cost of wood treated with safer alternative pesticides is about 10 to 20 percent more than the old CCA-treated products. Non-wood options are also considerately more expensive than the standard treated products, (about $2.00 a linear foot), but they require a lot less maintenance.
The EPA is NOT promoting the removal of existing CCA-treated lumber. Currently no scientific studies suggest this action is warranted.
If you want to reduce the risk of preservatives leaching, the application of a semi-transparent penetrating stain or a water-repellent finish has shown some promise in preventing the leaching of copper, chromium, and arsenic from treated wood products. These surface treatments will require annual re-application to maintain water repellency.
Source: NAHB & PATH
