What you should know about treated lumber and steel fastening solutions: While Chromated Copper Arsenate (CCA) had been used for decades to treat exterior lumber, the Environmental Protection Agency (EPA) has asked the lumber industry to cease the manufacture of CCA treated lumber as of January 1, 2004. Two core products have replaced most CCA applications; Alkaline Copper Quaternary (ACQ) and Copper Azole (CA). Although the new chemicals are proven lumber protectants and are much safer for people who work with them, an unfortunate side effect is the increased corrosive properties, as much as 3 times as corrosive of non-arsenate lumber treatment chemicals on steel, like staples and nails.   HERE ARE THE FACTS: 1.  Manufacturers and distributors who knowingly recommend and sell defective or inappropriate products that result in injury, property damage, or loss to a consumer may face significant potential liability. This requires fastener manufacturers to understand the interaction between the new wood preservatives and the fasteners, and then they must carefully communicate recommendations to the marketplace.   2. Non-arsenate based treated lumber is more corrosive to metal fasteners (and certain other types of metal hardware) than current CCA pressure-treated lumber. This has been proven in independent lab tests conducted by SENCO.   3. Wood manufacturers of non-arsenate based treated lumber strongly recommend hot-dipped galvanized or stainless steel fasteners with their treated wood products. Further, for fasteners exposed to high moisture and salt environments, manufacturers recommend stainless steel fasteners, specifically with a stainless grade of 304 or greater.   4. The long-term structural impact of non-arsenate based treated lumber on steel fasteners is not known at this time. SENCO is conducting tests with independent laboratories to determine the structural impacts, if any, from the interaction of these new chemicals with steel fasteners.   5. SENCO was one of the first manufacturers to proactively work with an independent laboratory at the University of Dayton Research Institute (UDRI) earlier in 2003 to develop protocols and to initiate lab testing. (UDRI has extensive experience in corrosion testing and protocol development for private industry and the US Air Force.)   6. Results to date have shown a far greater incidence of surface corrosion – both red and white rust – among fasteners driven into non-arsenate treated lumber versus the previous CCA treated lumber.   SENCO FASTENING RECOMMENDATIONS: While an industry standard has not yet been proposed, SENCO has used the early testing results to proactively develop a series of recommendations for fasteners to be used in exterior applications using non-arsenate treated lumber. 1.  First and foremost, SENCO recommends the use of stainless steel (grade 304 or greater) nails, as high-grade stainless steel provides the greatest level of corrosion resistance on the market today. Similar recommendations apply to screws and staples.   2. In less humid or salty environments, hot-dipped galvanized nails or staples may be used. While not as resistant to corrosion as stainless steel, hot dipped galvanized fasteners meet building codes and the requirements of the manufacturers of non-arsenate based treated lumber.   3. For screws-In less humid or salty environments, our Weatherex® 3 (class 1 galvanization with Magni polymer coating) may be used. While not as resistant to corrosion as stainless steel, Weatherex 3 screws meet building codes and the requirements of the manufacturers of non-arsenate based treated lumber.