Bulletin
Effective: Immediately
Date: September 27, 2006
Purpose: To advise individuals that there is a concern with materials used in construction.
Almost all available pressure preservative treated wood products in the market are ACQ treated wood. There are numerous cases of corrosion of connectors and fasteners with ACQ treated wood products. The increased copper content of the ACQ treatment compared to the previous CCA treated, and the ammonia in the new process appear to be increasing the corrosion rate.
Only stainless steel of type 304 or 316 fasteners and connectors are approved for use with ACQ treated wood products in all normal conditions.
Simpson’s Strong-Tie Z-Max connectors may be used with ACQ treated wood products if separated from the wood with Vycor protective wrap, and fastened with hot-dipped galvanized nails or bolts and protected from exposure to wetting.
Hot-dipped galvanized nails or bolts may be used with ACQ treated wood products if the wood is protected from exposure to wetting.
Exposed locations such as spaced open decks require stainless steel hangers, screws and nails.
Do not mix fasteners and connectors of dissimilar metals. Do not use any aluminum products near ACQ treated wood products.