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Environment Protection Authority

Environmental Issues

Chemicals and pesticides

Copper based alternatives to CCA

There are two main kinds of waterborne copper based alternatives to CCA: alkaline copper quaternary (ACQ) and copper azole (CA).

copper azole sleepers used as bush walkway

Copper azole sleepers used as bush walkway

ACQ (which may also exist as ammoniacal copper quaternary or amine copper quaternary) is a water-based timber treatment that uses copper to protect timber from fungi, and a quaternary compound to protect timber from copper resistant fungi and insects. It is applied by pressure treatment.

Copper azole uses copper in the same way as ACQ, with the addition of tebuconazole.

Hazard level: H3 to H5

Refer to the Hazard levels and chemical treatment types chart for more information.


Moderate to very severe decay, borers and termites

Typical uses


Both ACQ and CA are suitable for exterior flooring, framing, cladding, decking, fascia, pergolas, fence posts, retaining walls, handrails, outdoor equipment, garden furniture and building poles.


Outside, in-ground and above ground, contact with or in fresh water


Find out about safe handling

Page last updated: 12 May 2016