Galvanized steel can be used in contact with most woods, but some corrosion will occur with Western red cedar and some other green woods, which contain acidic substances. In generally galvanized fasteners are not attacked by wood or by insulation foams (e.g. polyurethane and polystyrene foams). Heavy corrosion may arise if the wood rots and forms a wet poultice against the zinc coating.
Timbers freshly treated with acidic preservatives of copper – chromium – arsenic type, such as Celcure, Copas and Tanalith, can be severely corrosive to metallic building materials, including galvanized coatings. Once the timber has dried out and the preservatives become fixed, the performance of galvanized coatings in contact is excellent, even when the timber is again wetted. Galvanized coatings also perform well in contact with boron-treated timbers.