Compatibility with Non-Metallic Substances

Timber is generally acidic, although some timbers—such as cedar—are more acidic than others. The interaction between preservative-treated timber and metal depends on the moisture content of the timber, the time of wetness and the type of treatment. The corrosion rates of metal in contact with wet CCA-treated timber and with untreated radiata are similar.

A printable bulletin is available at: BV01 Cavity Batten Protection V2.0.pdf

Extract:

"...The Code of Practice says that metal cladding should be separated from wet timber, treated or
otherwise. That is because both treated and untreated wet timber is corrosive, as wet radiata is
acidic...." 

Butyl Rubber in Wet Contact with Cladding

Butyl rubber in wet contact with coated aluminium and steel has been found to accelerate corrosion.