What is ACQ treated pine?

And how does it differ from other treatment methods such as CCA?

When it comes to the wood you use in construction projects, you want to get it right the first time.

In this post, we will cover all you need to know about ACQ treated pine.

What is ACQ treated pine?

ACQ is a water-based treatment that protects timber from the effects of weather, rot, fungi, termites and other insects.

All ACQ treated pine should have a Hazard level classification which determines its level of protection against certain exposures.

The following Hazard levels are treated using ACQ:

What does ACQ treated mean?

ACQ stands for Alkaline Copper Quaternary and is a water-based solution of copper, chromium and quaternary ammonium compounds.

It is applied by vacuum pressure impregnation, or VPI, which simply means that the treatments are forced into the timber.

It has been used as an alternative to CCA treated pine since around 2004.

CCA vs ACQ treated timber: what’s the difference?

CCA treated timber was the standard timber treatment until around 2003. ACQ is now more commonly used.

Both types of treatment are similarly effective in protecting the timber from insects and decay.

The main difference between them is their toxicity; CCA has been banned in many countries due to environmental concerns as it contains arsenic, a known carcinogen.

Instead of using arsenic, ACQ uses another compound called quat (or quaternary ammonia), which is less toxic.

This is an important factor for people who plan to use treated pine for their home DIY projects.

Is ACQ treated pine safe for vegetable gardens?

Many people prefer not to use CCA treated pine (which contains arsenic) for vegetable gardens. However, CSIRO assigns a tolerable risk, based on their research.

ACQ treated timber is generally considered safe to use as it does not contain arsenic and therefore poses less risk of leaching chemicals into the soil.

If you are concerned, you can line your vegetable garden with plastic or another material to prevent leeching.

Or better yet, use untreated hardwood sleepers as an alternative to treated pine.

Keep in mind that root vegetables are more at risk of absorbing toxins from the soil.


How long does ACQ treated pine last?

ACQ treated timber lasts a lot longer than most untreated timber. The life span of ACQ treated pine will depend on the conditions the timber is exposed to. However, in many cases, you can expect ACQ treated timber to last for 100+ years.