Every time we think we've solved one problem, we find that others have been standing in line to replace the one we've taken care of.

The problem we've taken care of in this case is banning lumber treated with chromated copper arsenate (CCA) -- used in deck construction for many years -- for residential use. Simply put, there were health concerns behind the ban.

The U.S. Environmental Protection Agency will continue to allow it in some industrial, commercial, agricultural and marine applications, as well as for most engineered-wood products such as plywood.

The reason: Arsenic is a known human carcinogen, and the agency believes any reduction in the levels of potential exposure is desirable.

The EPA, which initially was wishy-washy about the dangers of CCA, is now suggesting that 90 percent of all children face a greater than one in one million cancer risk from their exposure to arsenic-treated wood, the historic level of concern for the EPA.

In Southern states, 10 percent of all children face a cancer risk that is 100 times higher.

For several years, residential builders have sought alternatives to CCA-treated wood for decks and other structures, not only because of potential future liability concerns, but also because homeowners want products that are more maintenance-free than pressure-treated wood, which needs to be cleaned regularly.

Health -- at least not yet -- is not the issue with the new lumber treatments. These new treatments, while considered less harmful to humans than the arsenic in CCA, can cause a different problem: They can corrode metal connectors and fasteners more quickly. That's because they contain a higher level of copper than wood treated with CCA had.

These alternative lumber products treated with alkaline copper quaternary (ACQ) or copper azole (CA) are now on the market, sold under a variety of names (ACQ Preserve and NatureWood, among them).

There has been some concern about that copper leaching into water supplies during rainstorms, but there has been no data from government agencies addressing that potential. (The EPA is in the final year of a two-year study on the most effective method of sealing CCA decks to prevent the arsenic from escaping.)

Hot-dipped galvanized or stainless-steel fasteners and fittings are acceptable for use with ACQ-treated wood, manufacturers say. Aluminum fasteners and fittings are not.

Hot-dipped galvanized and stainless-steel fasteners always have been recommended for use in deck construction. But they cost more than the aluminum and electroplated galvanized fittings commonly used, though hot-dipped fasteners tend to be less expensive than stainless steel.

Corrosion is a process in which metal deteriorates through a chemical reaction with the environment. Some preservatives can promote the corrosion process by providing more favorable conditions for the conversion of metal into the products of corrosion.

A study by Simpson Strong-Tie, a manufacturer of fasteners, found that the new preservatives were twice as corrosive as CCA.

The rate of corrosion depends on other things, including salt water or air containing it, pollutants, wood preservatives, the presence of other metals, temperature, and relative humidity.

The National Association of Home Builders Research Center in Upper Marlboro, Md., further refines the rules on fasteners and fittings:

Stainless-steel connectors or fasteners cannot be used in combination with hot-dipped galvanized connectors or fasteners.

The more zinc on the surface of a hot-dipped galvanized fastener, the better it can limit corrosion. A lot of fastener manufacturers have been increasing the amount of zinc -- some up to 50 percent more -- to improve product performance.

Be aware, however, that galvanized fasteners are rust-resistant, not rustproof. Nothing says the fasteners will stay rust-free.

Some builders and a lot of do-it-yourselfers have not yet gotten the word about the fastener and fitting problems. And building officials -- when permits are sought -- are concerned.

These officials will most likely demand that the fasteners be replaced before they grant permit approval for the decks, which means that the cost of building one can be as much as doubled.

A lot of the 30 million outdoor decks that exist around the country have been done outside the permit process. It remains the responsibility of builders and do-it-yourselfers, then, to make sure that they are using the right fasteners and fittings for the job.

Among the products acceptable for use with the new lumber are Simpson's ZMAX (G185) hot-dip galvanized or stainless-steel fasteners; USP structural connectors/triple zinc G-185 connectors; PrimeSource fastening systems (PrimeGuard Plus coated fasteners); Osmose Pro-Drive screws; and Bostich Thickcoat.

Again, fasteners that are hot-dipped galvanized or stainless steel are the only ones to be used with the new types of treated lumber.

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