Most of the time, upper floors with cement, use a lightweight cement that is not recommended to glue over. Can you take a nail and easily scratch the concretes surface? A floating wood floor, may be your only option. All concrete will have moisture vapor emissions, no matter if it is on the ground floor or on the 100th floor. The only way to know how much, is to test it.

Right now, I'm back to the Wiccanders floating: the actual patterned layer of cork seems thicker. I still haven't seen the 'good stuff' of theirs with the finish containing ceramics, but that one has me spooked because it can only be re-finished by a Wiccanders approved company, you can't just buy it and apply it yourself. That could relate to their pattent, though: maybe it will become available down the road. I like the Durodesign glue down too, though: very cushy, and I'd like the option of having a little more pattern than the floating stuff. Less impressed by Simple floors and the others, though. Not only is the face layer of cork thin, the cushion layer is thin, too. The upside of the simple floors version is that the finish is kind of grainy and matte: much less slippery than the others. The tounge and grove of their engineered seems to be the same as for Globus natural cork, which I don't have a sample of. Yet.

Recipe for disaster. Concrete is porous, and thus absorbs moisture. When wood absorbs moisture, it swells. If it absorbs enough in the lower layer, with the top layer absorbing it slower, then you get cupping. Grooving will not prevent cupping. If you don't fix that constant transmission of moisture to the wood, then you get rotting. Wide plank already moves around a great deal, even when installed above grade on a subfloor. It will expand and contract with the seasons. That's normal. The wider the plank, the more movement you get. You need to maintain constant humidity in order to minimize the normal movement in wood. If you get hot and humid weather in the summer with no AC and don't use a humidifier in the dry winter air, then your wood floors, furniture, and cabinets will swell and shrink considerably over the seasons. That is NOT considered a defect. And this is why engineered flooring was created. It's basically plywood, with thinner layers of cross grained material. That means that each layer has minimal expansion and contraction, and because of the cross layers, it's much more stable. Combine that with a polyurethane glue designed to keep moisture transmission to a minimum, and that's the only consistent tried and true way to successfully have wood floors with slab flooring. It's the only way wood flooring is done here in the South, where humidity and concrete slabs are everywhere. It works, and there is no need to reinvent a square tire and call it a wheel.

A good deal of that info has to do with preventing moisture problems BEFORE the slab is poured. For installing wood flooring for those who aren't pouring a new slab, the author recommends a "fluid moisture barrier" rather than a plastic sheeting barrier, but doesn't say much (anything?) else beyond that. Is he suggesting something like Redguard?