Part of the problem is that fasteners and connectors are being used with treated lumber other than products made of stainless steel or hot-dipped (not electroplated) galvanized steel, contrary to the recommendations of manufacturers.
Although it is expensive, stainless steel is effective in combating corrosion from ACQ, CBA and CA. If galvanized steel is used, thicker coatings will probably be needed.
How much more these alternative chemicals will increase the corrosion of galvanized steel connectors and fasteners is not fully known because many factors are involved, including the thickness of the galvanizing, the species and moisture content of the wood, the chemical treatment used and the exposure of the materials.
The American Wood-Preservers' Association (AWPA); the International Staple, Nail and Tool Association (ISANTA); and members of those two groups are researching this issue and working to develop improved fastener and connector products. Standards for these products are also being reviewed and updated for their use with the chemical treatments that are replacing CCA.
NAHB staff is currently evaluating guidance on this issue for builders, and the information will be made available to all NAHB members when the evaluation is completed.
Until then, builders who are using lumber treated with alternative chemicals should check with the connector or fastener manufacturer for guidance.
For further information, e-mail Jeff Inks or call him at 800-368-5242 x8547.
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