Pressure treated yoods

[ted655]

Is anyone using PT woods in any part of there construction?
The new formula, ACQ? What adhesieves & fasteners are you finding satisfactory?

[Raggi_Thor]

The pressure has crushed the cell walls in the wood, so it's like a sponge.

[gonzo]

There are several adhesives that work well. It depends on what you are building. Liquid Nails and other solvent based glues adhere very well. The lumber is usually waterlogged because of the process. I don't believe there is any cell crushing. The pressure only accelerates the capillary action. The Wood Institute doesn't list PT lumber as weaker. The new type is treated with borates. They are not as corrosive as the older copper and arsenic salts.

[Raggi_Thor]

OK, maybe it's just Norwegian popular beliefs, the crushing I mean.

[gonzo]

The pressure is only about 15 PSI-103Kpa

[Raggi_Thor]

OK, when you buy this kind of wood here it's so soaked it barely floats in salt water. When you use it to make an outdoor floor the planks shrink 5% or so.

[ted655]

We use it alot here in Louisiana. It drys pretty well after a month (IF it's off the ground) of exposure. It has some shrinkage, but not as much as you report. The problem is the change from the old formula to this new one. I have contacted 6 adhesive manufactures & none of them will garuntee their product to adhere to the new PT woods. the wax content is too high in the new formula. Florida building codes require only hot dipped galvinized or SS fasteners be used. This stuff eats aluminium & electroplate coated fasteners like candy. If used around or in saltwater, the SS will also be eaten away. This new PT is nasty stuff.
I've only heard of 1 supplier of Borate treated wood & it is SUPER expensive.
I was hoping someone had found an adhesive they were confident with.