Decorative Finish | Sweep Blasting | Thicker Galvanized Coatings | Galvanized Steel in contact with Timber | Steel Detailing | Safe Buildings | Imported Steel Products | Advantages of After Fabrication Galvanizing | Standards Update | Materials Handling & Conveyors | Lintels and Shelf Angles | Zinc for Human Health | Atmospheric Corrosion Resistance | Paint over Galvanizing | Abrasion Resistance | Use of Galvanized Reinforcement | Repair of Field Welds | Wet Storage Stain | Distortion | Thickness on Flame-Cut Edges | Coastal Construction

Galvanized Steel in
Contact with Timber


Advisory Note
GEN/17/1
September 2001

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.

References:
1. Corrosion Resistance of Zinc and Zinc Alloys
International Lead Zinc Research Organization, 1994

2. After-Fabrication Hot Dip Galvanizing - A Practical Reference
Galvanizers Association Australia, 1999