by Judeyramone » Sun Sep 05, 2010 5:22 pm
Southern yellow pine is what has been commonly used for treated lumber because it's a very dense durable wood, even untreated... and it's ugly; Unsuitable for decorative uses, primarily because it has too many knots. Wooden ladders are made of it as well, for the same reason. Select pine, or white pine - the 1x4 or 1x6, etc. boards you get at HD and lumber yards (if you're lucky enough to still have one near you), is an entirely different species, much less dense, less strong, fewer & tighter knots, and MUCH softer. I wouldn't use it for much of anything structural that you expose to the elements. I trimmed my garage with it, but not before priming both sides, and many coats of paint on the exterior surface.
IIRC, from my lumber yard days, the coding for plywood indicates ACX would be sanded on both sides (AC), exterior (X)... much like exterior wall sheathing (commonly referred to as CDX - CD=not finished on either side, X=exterior). As far as I can remember, the X rating comes from the fact that the plywood is assembled using an exterior glue, but it really doesn't hold up to the elements at all. It's basically glue that can withstand the elements long enough for your contractor to cover your exterior wall sheathing with siding. There is no plywood that will not delaminate w/o careful prep & maintenance. If you've ever seen an old wood garage door that was falling apart, the first part to go is the plywood panels.
All options you mention are going to rot, especially red oak - don't use that w/o many coats of waterproofing.
I'm gonna throw my hat into the treated lumber circle, but with this caveat:
Treated lumber is milled, bundled, and then dipped into the treating solution in very large bundles, and remains in those bundles until lumber retail workers bust them open & stock the boards on shelves at Home Depot. That's why those boards (especially the ones in the middle of the bundle) are usually wet when you buy them. Unless you let it dry out thoroughly before use, you will experience considerable shrinkage when it does dry out (this is why you are not required to space treated decking boards) - and...
Boards that are dried too quickly, or improperly, bend twist & warp - especially treated southern yellow pine, especially if it's 3/4" thickness. I suggest you find the straightest, truest, driest treated lumber you can, and let it dry in your garage before use, stacked horizontally with 1/4" spacers between each board and cinder blocks on top, every 2 or 3 ft apart.
