Avoid corrosion caused by contact with timber

Green timber or timber treated with copper chromium arsenic (CCA) should not come into direct contact with galvanized steel, ZINCALUME® steel or COLORBOND® steel because acidic substances from these timbers have a corrosive effect on the metallic coating. The time of wetness of the metal surface is a factor in the overall corrosion mechanism (the longer the product is wet, the greater the corrosion).

Even run off from CCA treated timber can contain corrosive leachate which will cause corrosion if it contacts galvanized steel, ZINCALUME® steel or COLORBOND® steel.

BlueScope Steel recommend against the use of CCA treated timbers for high moisture situations such as roof and ceiling batons, composite fence constructions and built up flooring or external decking which may utilise a metallic coated steel structural support system.

If CCA treated timbers must be used, the timber and/or steelwork must be sealed by fully painting the material prior to installation.

The use of kiln dried or appropriate dried timber species is recommended for any situation where intimate contact between the metallic coated steel and timber is considered.

For more information, please download "Corrosion Technical Bulletin 13 - Contact with timber".