Pressure treated wood -- ACQ?

[zxcvbob]

I was looking at lumber for building raised beds in my garden. I was planning to use untreated 2x6's for the sides and ends, and pressure treated 2x4 stakes in the corners and joints. (I would use creosoted 2x4's if I could find them.) I live far enough north that I don't have to worry about termites.

Home Depot has some new pressure treated lumber that's supposed to be non-toxic; it's treated with ACQ instead of CCA. "Alkaline copper quaternary." Has anyone heard of it? I haven't bought anything yet until I do some research.

-Bob

[hollenback]

Bob Things you should be aware of with the new ACQ lumber.

1. There are different grades of it. You should be looking for wood labeled for ground contact.
2. The copper will corrode galvanized or zinc plated screws and nails. If you expect it to last you will need stainless steel hardware or at least double dipped galvanized.

Does anyone here know at what level copper is toxic to plants?

Boron treated lumber is another alternative but in high levels boron is also toxic to plants.

Personally with all I have heard about the new PT lumber I will wait until more is known about them.

Bill

[zxcvbob]

I was planning to use bright 16d nails. I don't care if the stain, and it should take a *long* time to rust through a 16d nail.

The copper level shouldn't as high as the bordeaux mixture or copper oleate fungicide sprays.

Best regards, Bob

[Stephen M. Henning]

Greenhouses have been using 20% copper-naphthenate preservative on greenhouse benches for decades with no problems. Cuprinol is one brandname for this product. The copper is no problem. I don't know anything about ACQ.

[Salty Thumb]

Father Haskell wrote in news: [e-mail]:

aside from the fastener issue, madgardener said something about the fungicide on some new lumber needed to be washed off or something about rotating stock after 4 months (not an exact quote). I thought that was kind of strange.

[Roy]

Cuprinol in some awfully good stuff. The green color preservative IIRC is guaranteed against rot for 20 years if you just soak the luimber with it first, but I have used it since the early 70's, in the green color as well as their other colors and its super. I went to Avon Conneticut one time to pick up a load of Cuprinol at the factory there, and they had all these various samples of just brushed on wood with cuprinol and others that were just soaked for various time periods all out in their test yard, and it all looked great. Back when I made that trip it was not available in our area, and it was cheaper and faster to run to Avon, Conneticut and pick up a pickup truck load than it wa to have it shipped. I was introduced to it when I did some work in a marina in New London, Conn, as it was very popular way back then for use in marinas and docks etc.

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[Father Haskell]

None of it is suitable for ground contact. Use plastic or concrete footings.

Exactly. I've been told to expect old style hardware to corrode to nothing in under 6 months.

[Stephen M. Henning]

The green is 20% copper naphthenate and is recommended for greenhouse uses. The other colors are other chemicals.