A. Merritt Kline, a product support specialist with APA/The Engineered Wood Association and the Southern Forest Products Association, and Bob Clark, an engineered wood specialist with APA, respond: According to the American Wood Preservers' Association ( www.awpa.com), recommended preservatives for plywood and southern pine lumber intended for use in the construction of permanent wood foundations (PWFs) include .60 alkaline copper quat — types C and D (ACQ-C and ACQ-D) — and .31 copper azole — type B (CA-B) — in addition to .60 chromated copper arsenate (CCA).

Unfortunately, the Southern Pine Council's Permanent Wood Foundation Design & Construction Guide (which can be downloaded at newstore.southernpine.com/cgi-bin/newsopine/product?;32) does not address this new generation of waterborne treatments. However, there's no reason to believe that fundamental design and detail recommendations would be...

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