The Best Treated Timber for Your New Windows

17 January 2017
 Categories: , Blog


How old are your timber windows? Older timber windows can be susceptible to termites and other burrowing insects, so if you're looking to upgrade your windows, you will want to ensure that they're suitably protected. This protection is generally as straightforward as buying timber windows that have been treated with an appropriate repellant. This treatment will stop termites and other burrowing insects from making their way into the wood, as well as preventing premature decay. There are a number of different treatments available, so it's all about finding the best product available within your budget.

Chromated Copper Arsenate

Chromated copper arsenate is becoming less widely used in timber for residential projects, but timber treated with this product is still available. It's an effective wood treatment that gives the wood a distinctive greenish tint (which can of course be painted over). The concern with using chromated copper arsenate is that it's believed that the treatment can pose a minor health risk to humans who come into frequent contact with the treated timber. Small amounts of arsenic can potentially leach out of treated timber, which can theoretically affect humans. It's likely that only children, the elderly, and those with a compromised immune system would feel its effects.


Australia has introduced some restrictions on the uses of timber treated with chromated copper arsenate. It should not be used to construct a number of items, such as children's playground equipment, garden furniture (including picnic tables and external seating), domestic decking boards, and handrails. It can still conceivably used to construct timber windows, and yet it's probably best to err on the side of caution and look for a safer product.

Light Organic Solvent Preservative

The safer bet is wood that has been treated with a light organic solvent preservative (LOSP). This method is also highly effective, but unlike chromated copper arsenate treated timber, there is no risk of toxic materials leaking from the treated wood. The timber is infused with a solvent made using white spirit (mineral turpentine) and is then sealed with a primer. This primer is pink in colour, and yet this merely seals the timber during the infusion process and can be removed during the construction process.

Depending on your budget, you might be considering chromated copper arsenate treated timber, but LOSP treated timber is certainly the better choice. It's widely available, so it's not as though you will need to look too hard to find a timber window manufacturer who uses timber treated in this manner.