Treated Timber from Timber Merchants

The treated wood I buy from my local timber merchants (Stoke on Trent) is pressure treated. I still have sound wood that has been out in the garden for over 12 years, it looks just as you describe.

It's pressure treated so the outer ~5mm are pretty rot-proof (and the remainder is protected because the outer 5mm prevents any oxygen getting in).

However if you cut the outside away, the remainder can be vulnerable, so you should soak it well in preservative.

There are two methods of treatment dipping and pressure treatment. Fence panels etc are usually dipped as the timber is thin. The pressure treated goes in an autoclave, vaccuum is drawn and the trreatment sprayed on. Peneration depends on howmuch of a vacuum is pulled. I watched one that seemed pretty dodgy to me.

The green is just dye to show it has been treated. Peneration seems very variable to me. You are supposed to treat cut ends.

At one time the treatment was with copper and arsenic salts. Chromium now I think. Not as good as the previous stuff.

I rejected a batch destined for my roof a couple of years ago as it was obvious they had been dunked in a tank while still banded together. The inner faces of the inner timbers in the bundle weren't even green on the outside never mind any penetration !

Andrew

Now that wouldn't surprise me.

The treatments allowed to be applied were seriously dumbed down some years back. Outdoor garden timber - the treatment now is pretty much completely useless. OTOH, I do question if it was ever needed - my

The only timber which was still allowed to be pre-treated with anything nasty enough to really work was roofing battens. Don't know if that's still allowed today.

Roofing battens have such a high moisture content it's difficult to see how there would be room for any preservative. At least twice the weight of joinery quality IME

Isn't that because when you buy them they have not dried out from the pressure treatment which might only be a few weeks old?

True. Any product that was really effective at anything has been banned, it seems. I'm guessing creosote (the stuff we used back in the day) went the same way as I haven't seen that around for a long, long time now.

Yep. Its easy to make - we need a ukdiy creosote still design.

NT

(Real) Creosote is still available to the 'professionals' which around here seems to mean the ability to buy it in 25l quantities