May 26, 2004 | By: Laura Skillman

With changes in preservatives used to treat lumber, new products are now in area lumber yards and home supply stores.

The treated lumber industry voluntarily decided to move away from using chromated copper arsenate, CCA, in virtually all residential uses such as decks, playground equipment, picnic tables and landscaping timbers by Dec. 31, 2003.  Lumber already in the pipeline can be sold, but many of the new products are already in the market and there is not a great deal of the CCA-treated wood remaining, said Doug Overhults, agricultural engineer with the University of Kentucky College of Agriculture.

CCA-treated wood is still registered for use by the United States Environmental Protection Agency in industrial applications, marine applications and most agricultural application, he said. EPA does not recommend removing or replacing existing residential structures constructed with CCA.

The newer materials are heavier in copper which is more corrosive and between 15 to 20 percent more expensive, Overhults said. Consumers should be aware that different fasteners are suggested because of the corrosiveness of these new preservatives.

“It’s kind of early and we don’t have a lot of experience with these preservatives, but the recommendation right now is to use a heavy galvanized nail or fastener or hardware,” he said. “There’s an industry standard G-185 that essentially means 1.85 ounces of zinc per square foot of material. The other choice is stainless steel, which is more costly, and in some flashing materials, copper. Avoid using aluminum with any of these materials because it will deteriorate very rapidly.”

Corrosion is worse under wet conditions, which is one of the main reasons for using treated lumber on items such as decks and playground equipment.

“Corrosion is the biggest difference between the old and new material,” Overhults said. “The average consumer won’t see much difference but the corrosion could surprise them, and if it happens to be a structural supporting connection, then it could be disastrous.”

Overhults said there is some uncertainty about the current availability of the heavily galvanized fasteners. That will improve over time and other alternatives are likely to be developed, he said.



Editor: Laura Skillman 270-365-7541 ext. 278
Source: Doug Overhults, 270-365-7541 ext. 211