ACQ Treated Wood Applications
Beginning January 1, 2004, the wood treatment industry agreed to halt production of lumber pressure-treated with Chromated Copper Arsenate (CCA) for residential applications in response to EPA concerns about arsenic (a known carcinogen). The leading candidate to replace CCA is Alkaline Copper Quaternary or ACQ. While ACQ is deemed safer because of its non-arsenic content, studies have shown it to be three times as corrosive to metal fasteners as CCA.
The highly corrosive nature of ACQ and its structural impact on metal fasteners has created much concern and confusion in the construction industry. Misleading claims by some manufacturers, boldly stating that their coated fasteners are “ACQ Approved” before the development of new test procedures and accepted performance standards, have further added to the confusion.
Perma-grip® Fasteners, along with another nail manufacturer, worked with an independent third party to perform accelerated corrosion resistance tests of the Perma-grip® fastener in ACQ treated lumber. The conclusion from the test is that the Perma-grip® spiral shank fastener appear to provide performance equivalent to hot-dipped galvanized reference fasteners (as recommended by the building codes for use with preservative treated wood) in contact with ACQ and CCA treated lumber.
As with any fastener in an ACQ treated lumber application, estimates of its service life cannot be provided due to the many variables that the fastener is exposed to, including (but not limited to) the chemical retention level in the wood, species of wood, and environment.