Corrosion of zinc-coated nails used with preservative-treated western red cedar shakes in service
R S Smith, E L Johnson, A J Cserjesi
The corrosion of metal fasteners used with certain wood species and with preservative-treated woods can be a serious problem. The chemical reactivity of western red cedar (Thuja plicata Donn) extractives to iron and copper is well documented and wood preservative treatments containing copper, chromium, and/or ammonium hydroxide can be expected to similarly attack some metals. This problem is compounded when red cedar is treated, and, such treatments with CCA and ACA have become customary in current efforts to extend the service life of shingles and shakes. Present recommendations for shake and shingle roof applications specify the use of hot-dipped zinc (iron) or aluminium nails. However, the use of nails made of stainless steel or other alloys of greater cost is advised with preservative-treated wood products.