ACQ Pressure Treated Lumber - An Environmental Improvement

The new pressure treated lumber is different. Get ready to see the letters ACQ, short for Alkaline Copper Quaternary, the latest improvement to treated lumber.

For years we have heard of the growing evidence about the dangers associated with the arsenic based chemicals in pressure treated lumber that leach into the soil, on to our hands and other means of transfer from our decks.

ACQ treated lumber is, in this respect, a welcome change. The forest products industry tells us that this new pressure treated wood with ACQ is as effective as the earlier CCA, (Copper Chromate Arsenate) pressure treated lumber. And we are a year into the voluntary withdrawal of the previously arsenic based lumber.

But the change in chemical pressure treatment brings some new issues that deck builders should be aware of.

ACQ Pressure Treated Lumber and Metal Corrosion

Unfortunately, the environmental benefits come at a cost, but worth it nonetheless. The new chemicals are much tougher on metal and can actually corrode some of the traditional fasteners we have become used to using.

The old galvanized nails for example will not last as long - at least that is what some preliminary tests seem to predict. We are learning more about this phenomenon and will keep you updated. But as we learn more we will update this page.

So our advice is just be sure you are using the new galvanized nails that are designed to be used with ACQ treated wood. Don't take the chance of building your entire deck with the old galvanized nails, screws and joist hangers only to find out 4 years from now that you have a corrosion problem to deal with.

Use The Right Fasteners

When you go to your local home improvement store be sure to talk to the staff and buy only nails, screws and joist hangers that are safe to use with ACQ pressure treated lumber.

Exterior Screws & Deck Fastening

EB-TY® Hidden Deck Fastening System

Exterior Woodmaster Square-X Screws & Kits

Woodmaster Exterior Deck Screws

Stainless steel brackets are known to withstand ACQ well. So you will see more and more fasteners like stainless steel entering the market. Fortunately most of the manufacturers of nails and fasteners have already come out with ACQ lumber compliant products.

But get ready to hear more about ACQ treated lumber as it becomes more and more commonplace throughout the country and replaces the older types of pressure treated wood.

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