Good solid timber has been used for centuries to build our homes, yards and other parts of our infrastructure. It has not only been used extensively in Melbourne, but all across Australia as well. Timber, being derived from the wood of a tree, naturally decomposes once it is dead and exposed to the elements. To combat this, several forms of treatment have been invented to help preserve timber items for many years to come.
Two of the main timber treatment types used in Australia are Lifewood CCA Preservative (Chromated Copper Arsenate) and Naturewood ACQ Preservative (Alkaline Copper Quaternery). Because most timber products are available with the option of either CCA or ACQ, it pays to know both their strengths and differences.
CCA was created as a fungicide and termiticide and has become the most widely used treatment for timber products. As one of the strongest and most effective chemicals available for protecting timber against termites and fungal decay, CCA is widely available and more cost effective than ACQ. Applied to wood via pressure treatment, it has been known to last a few decades in outdoor conditions, ensuring durability and longevity of timber. Despite having many strengths, research on CCA has led to some concern over the safety of the chemical makeup of the preservative. It contains an inorganic arsenic that penetrates the wood and is suspected to be hazardous in applications that allow for intimate contact with humans and animals. Because of this, it has been restricted by the APVMA in Australia for use in applications where close human contact is a risk.
You will find CCA being used mostly in timber sleepers used in retaining walls, verandah posts, farm fencing, building timber, marine use, weatherboards and fence lattices. It is banned from use in Australia in garden furniture picnic tables, exterior settings, children’s play equipment, handrails, and patio and domestic decking. Fortunately, ACQ has been deemed to be an approved alternative for use in these applications.
ACQ is a waterborne form of treatment. As a matter of fact, it was developed as a safer alternative to CCA and is used as an insecticide and fungicide. The chemical makeup of ACQ is formed when the compounds copper and quarternery are combined, creating an effective timber protector. ACQ is similar to CCA in effectiveness and does not contain any arsenic, greatly reducing its toxicity and risk of being a hazardous preservative.
You will find ACQ commonly used in all the applications which CCA is banned from being used. The reason that CCA is still used is because the cost of ACQ is higher and its availability is currently more limited.
Selecting the right treatment solution for your timber requires you to look at where the timber is being used and making a decision accordingly. For all applications that involve close human contact, ACQ is required. For all other applications, CCA can be used (though you can still opt for ACQ if you’d like).
What are you using your timber for, and which timber treatment will you select? Let us know in the comments.