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CCA (Copper Chrome Arsenate)

CCA is a water-borne timber preservative for H3-H5 hazard classes. Contains arsenic; APVMA restricted from 2006 for high-contact uses. Builder primer on safe use.

By Chalkline. Last updated 14 May 2026. Verified 14 May 2026.

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CCA stands for Copper Chrome Arsenate, a water-borne timber preservative that has been used for decades in Australia for in-ground and weather-exposed timber. It contains three active metal compounds (copper, chromium, arsenic), each playing a role: copper as fungicide, chromium as fixative, arsenic as insecticide. CCA gives timber a distinctive green tint that fades grey over years of weather exposure.

Hazard class range. CCA achieves H3, H4, H5, and H6 ratings under AS 1604.1, making it the historical default for:

  • Outdoor decking, posts, retaining walls (H3 to H4).
  • In-ground fence posts, garden edging (H4).
  • Boardwalks, sleepers, marine piles (H4 to H6 depending on exposure).
  • Landscape sleepers and retaining-wall logs (H4 to H5).

The 2006 APVMA review and restrictions. The Australian Pesticides and Veterinary Medicines Authority reviewed CCA in 2005 and issued restrictions from 2006 on uses where humans (especially children) have prolonged direct contact:

  • No use in playground equipment, picnic tables, garden furniture, handrails.
  • No domestic-use restrictions for fencing, retaining walls, garden edging, structural decking sub-frames where direct skin contact is not prolonged.
  • Disposal restrictions: CCA-treated timber must not be burned (the smoke releases arsenic). Landfill disposal only.
  • Cutting restrictions: dust from CCA-treated timber is hazardous; wet cut or extract with on-tool dust capture, wear P2 respirator, wash hands after handling.

The post-CCA landscape. Newer preservatives (ACQ, copper azole) have replaced CCA in many residential applications because:

  • They achieve similar H-ratings without arsenic.
  • The treated timber looks similar (still copper-greenish).
  • Disposal is less restricted.

CCA is still available and legal for non-restricted uses. For visible deck surfaces, handrails, and landscape elements with hand contact, ACQ or copper azole is the modern default. For sub-deck framing, fence posts, and concealed elements, CCA is acceptable.

Identifying CCA. The grade stamp on treated timber identifies the chemical: look for CCA, Tanalised C, Permapine CCA, or similar mill-specific markings. The visible green tint is a strong indicator on freshly-treated timber; aged CCA fades grey and can look similar to untreated weathered pine.

For builders.

  1. Don’t use CCA where the APVMA restricted it. Children’s playground, garden furniture, handrails. ACQ or copper azole instead.
  2. Cut CCA wet or with extraction. The dust is the highest-exposure pathway. P2 respirator at minimum.
  3. Dispose to landfill, never burn. Even small offcuts. Burning CCA releases arsenic into smoke that is acutely toxic.
  4. Spec the modern alternative at quote stage on contact-sensitive elements. Save the CCA debate by speccing ACQ from the outset.

Also known as: Copper Chrome Arsenate, CCA-treated pine, Tanalised C.

Category: Materials / timber / treatment.

See also

Last updated: 2026-05-14. Verified: 2026-05-14.

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