CCA Timber Treatment
Chromated Copper Arsenate (CCA) is one of the world’s most popular wood preservatives and has been in use for more than 75 years and has broad-spectrum usage and efficacy.
CCA treated timber is odourless, safe and easy to handle after treatment, and requires no special equipment during installation. It has a service life of up to 25 years, although CCA treated wood can last for 40 years and longer.
A water-borne preservative, it offers timber long-term protection against wood-destroying fungi, insect larvae and termites and is used for structural timber, agriculture poles (pine and eucalyptus) and transmission poles.
- CCA is impregnated into the timber by vacuum and pressure at our timber treatment plant during a 2-hour process in the pressure cylinder that is monitored by the SABS to ensure compliance with their specifications.
- Once the process is complete, the timber is left slightly damp, allowing the solvent (water) to evaporate over a few days.
- The active ingredients in this treatment are chromium (47.5%), arsenic (34.0%) and copper (18.5%), with the extraordinary effectiveness of CCA lying in the combined action of these three elements.
- Copper inhibits the reproduction of bacteria and also acts as a fungicide, preventing the growth of fungi such as Lenzites trabea, Poria monticola and Lentinus lepideus from using preserved timber as a potential food source. During the preservation process, the divalent copper ions bond to the cellulose and hemicellulose in wood via a redox reaction.
- Chromium allows the CCA to penetrate deeply into the wood, and for the arsenic and copper to form permanent bonds with the wood. The greenish hue of trivalent chromium can be seen in the pale green colour of CCA treated wood.
- Arsenic is used as a secondary fungicide, making the wood resistant to even copper-resistant fungi. It also functions as an insecticide, leaving wood resistant to attack from xylophagous and detritivorous wood borers.
- A relatively inexpensive treatment ideal for exterior and interior use.
- Water-based therefore not recommended for products with a high tolerance fit i.e.: tongue and groove products.
- It leaves a greenish tinge to timber and therefore is not advisable for timber where an uncoloured finish is required. (Use Vacsol Azure clear treatment for this).
- Although not normally necessary, CCA Treated timber can be painted, as long as the correct type of paint is used.
Depending on use, CCA treated timber is treated to H2, H3 or H4 classifications:
- H2 Internal – Low Hazard: Timber framing and roof trusses
- H3 Exterior above ground – Moderate Hazard: Decking, fencing, garden furniture, gates, external cladding
- H4 Ground contact – High Hazard: Fencing poles, Deck support poles