The dark side of treated timber
Most of us know that for a softwood like radiata pine to be used outdoors, it needs to be treated with preservative to protect against fungal decay, insects and the elements. There are different levels of treatment for different applications, such as:
H3.2 for above ground such as weatherboards
H4 for ground-contact such as fence posts
H5 for structural uses such as piles and high retaining walls
The vast majority of treated timber available in New Zealand is treated using Copper-Chromium-Arsenate (CCA). CCA treatment, primarily the arsenate, is toxic and there is risk from exposure to the dust from cutting it, the toxins released if it is burned, and even simple skin contact.
CCA treatment has been banned or restricted in many developed countries for over 20 years. You cannot use it in the UK, US, Australia or the EU for high-contact residential applications - yet in New Zealand we allow our kids to play on CCA-treated play equipment, and our builders to handle CCA-treated timber and breath in its toxic dust.
There is an alternative
It doesn’t have to be this way. An alternative method of treatment, which still results in H3.2 (or H4 or H5) timber, is Micronized Copper Azole (MCA), which has been approved under New Zealand building standards - see page 27 - since 2003. Compared to CCA, MCA treated timber:
Is much less toxic than CCA-treated timber to people, animals and the environment
Is just as well-protected as CCA treated timber
Has better end-of-life options for re-use or recycling
Has a warm brownish colour instead of the green tinge associated with CCA
To be abundantly clear, MCA treatment is not an alternative to H3.2, it is alternative to toxic CCA. Timber treated to H3.2 using MCA is H3.2 timber!
The million dollar question - cost
OK, yes MCA currently costs a little more. But really, not much! I just quoted someone on decking and MCA was 6.2% more expensive. 34c per meter. To significantly reduce the risk of health and environmental issues, this seems like a small price to pay.
It seems likely that the cost is at least partly due to its rarity. If everyone bought MCA timber, it would probably bring the cost down as the treatment companies would leverage economies of scale. But MCA timber is hard to find at the moment.
So what?
We want to make a difference on this issue. We already stock the best quality timber in town, in terms of it being dry, straight, clear of defects and beautifully machined. We would love to offer the safest treated timber as well, but we want to know what you think. We know, you’re always being asked to do surveys, so we’ve kept this one to three simple questions!