With 1/2", all you should need for nailing is 3/4" CDX plywood. You can float it or glue and nail. I prefer the glue and nail method. It would be advisable to moisture test the slab first. And even if it reads ok now, using Bostick's MVP and gluing the CDX down with Bostick's Best is what I would recommend. 6 to 8 mil poly is fine if you are going to float the underlayment. One thing, you may want to glue that pine down as well. Reason is that the T&G was milled for siding, not flooring and I'd bet the fit is a lttle sloppy; not snug as you'd get with flooring. Also, 1/2" is a little thin to rely on nailing only for 6" wide planks. Just my opinion. That's how I'd do it.
Wow, thanks a ton! I hate to sound like an idiot, but could you describe the "glue and nail" method?
1. Glue vapor barrier to concrete?
2. Glue plywood to barrier?
3. Glue and nail pine to plywood?
And the fit isn't the best, but looks good for the look we're going for. Mom's ended up fitting pretty close, but the lumber yard she got the wood from sent her some crap boards, so we had to nail down a board and use a wedge to get the boards in line - it was a pain but worked well for crooked boards. If they were too crooked, the lumber company was happy to exchange them. I'm doing around 440 square feet at first. The living room is sunk, but should be above grade, but given that, is there somewhere I can rent a moisture meter/tester? I bet they're pretty expensive to purchase.