Dr Woeste at Virginia Tech has sent a couple of emails around about changes in treated lumber rules that are coming down the pike. Here is an article in JLC about those changes. Still in flux, keep your ears open;
http://www.jlconline.com/how-to/exteriors/treated-wood-deck-framing-rules-get-tougher_o
Thanks for that. I saw the JLC article and then promptly forgot d*
The rule I'd like to see is they can't make it out of southern yellow pine anymore....that stuff's the worst....
I have seen some so bad that if it wasn't nailed up wet it was a pretzel after it dried... d*
Southern pine accepts treatment better than any other commercial wood. It has larger, longer tracheids (softwood cells) than the other woods. Most western woods require incising which isn't as good and also carries a 15% strength penalty due to the damage from incising.
One of our small local yards sort of specializes in his treated lumber. He buys #1 SYP and it seems to be much better material most of the time. I was in Lowes and was about to buy some 6x6's for a porch while there. They were rated for above ground. That would be ok from the porch floor to the roof but isn't one I'd put under the floor. They know most people can't tell the difference, pretty sneaky IMO. But yes, I've had SYP break screws while drying, twist, cross check... all the cussing aggravations.
I am planning to build an outhouse using 1x6 fence boards for the siding. I wanted to cut the long edges on a 45 degree angle to help with privacy if and when the boards shrink. If I buy wet wood, cut them, then stack them with shims and heavy blocks to hold them down, will they still twist out of shape?
Side note: The new stuff they sell at our big orange is Sienna brown, not the old green stuff anymore. Not sure if there is any difference with respect to the treatment or twisting.
One way is to order KDAT, kiln dried after treatment, I'll be doing that for the T&G porch floor. Most drying problems will have shown themselves and can be sorted out then...$ you're paying them for infrastructure, time and energy.
Air drying, I would dry first and cut after, end splits. Make sure you have a row of stickers near the ends and then about every 2'. The stickers need to be in good vertical lines as well to keep from bowing the boards as the weight stacks up. The Wood Doc says you need about 4,000 lbs on top of a stack to keep what you can flat (not all can be saved). So yes, some will warp, split, whatever, this is called drying degrade. In my view I'd rather lose those boards on the pile than on the building, I like to work with wood as dry as possible. Since I just about never have that kind of weight, I've used the 20', 10,000lb ratchet straps to cinch down the pile with stuff that really wants to move. Tighten them every few days. With most wood I just have the timbers or blocks that hold the tin down for weight and the wood does fine. Dry out of the sun, up off the ground, under a roof of some type, with plenty of airflow through the stack.
The brown treated I've dealt with in the west is Sunwood, a brown stain applied during a light treatment process, an above ground product. Get a pic of a label and I'll decode it if you like. Read into the comments on this article for a little;
http://www.buellinspections.com/not-all-pressure-treated-lumber-is-created-equal/