Any wood flooring over concrete in contact with the earth usually requires the services of an experienced professional to get it right the first time. Whether or not you're going to install plywood first (an obsolete method in my professional opinion), the concrete needs to be FLAT and you need to make it flat before starting the job. Wood manufacturers will state how flat that needs to be. And, you need to know how much moisture is coming through a slab before you do anything to it or apply any flooring to it.

Good input guys. Thank you very much! I've had a couple tile guys come out to provide quotes, just one moments ago. His thinking was to mud or mortar the whole thing, including the kitchen, so no Hardibacker or Ditra, which I was leaning toward... I guess the benefit there would be the ability to make the elevation the same in both the entry way and kitchen... It would 1/2 inch though, on top of the underlayment, then thinset, then tile. That becomes higher than anticipated, and possibly problematic with respect to a transition to carpet in the living room and the DW fitting under the counter. The other tile guy would jackhammer the mortar bed, remove it and use wood to build it up. He'd use 1/4 Hardibacker, however nail those down with roofing nails. He does put some thinset on the bottom of the Hardibacker though. Not so keen on roofing nails on the Hardibacker, but maybe with the thinset under, it would be fine....

Solid wood expands and contracts as its moisture content changes. The moisture would absorb from the ground, through the slab, causing the individual boards to get wider, pressing against each other with great force. Theoretically this could loosen some of the boards, potentially buckling the flooring. It would also tend to crush some fibers along the edges of the boards, so that cracks would open between them should they dry out for some reason. If moisture problems were bad enough you could be creating a haven for mold between concrete and wood. I'm a woodworker but not a flooring expert, so take the following with that in mind: You could get a sense of how much moisture is coming through your slab by taping a piece of plastic sheeting to it, duct tape all the way around, for a day or so. This is a test I've seen recommended when people are considering painting a concrete floor. If moisture condenses under the plastic then you have a significant vapor transmission issue that should pretty much tell you not to put any flooring down at all unless you improve your foundation drainage. If it passes that test, perhaps you could get away with it. I still think I'd want some sort of moisture barrier seperating wood from concrete, perhaps a plastic membrane as is sometimes used for tile, or even paint if you're on a budget and feeling lucky. That's the direction I'd head in, but remember: not a flooring expert.

Hi Monica! Well, here's what I was able to come up with: most new home construction in the US is built with subfloors. Homes with basements or crawl spaces are built with subfloors. Cement slabs are more common in the southeastern region of the US. The pros of subfloor are that you can access stuff if you want to remodel or need to re-do your plumbing and you don't want to have to crack up the cement slab to get to that stuff. Laying down hardwood can be trickier with cement slabs because they often retain moisture. Also, cement is hard. Hard on joints of us old folks who aren't getting any younger. However, you can do pretty neat radiant heat with a cement slab, so toes stay toasty! Some people like slabs because they don't get the critters and bugs like you get in your crawl space. Also, you can use it as a finished floor, unlike a subfloor, where you have to lay something on top of it. But that brings us back around to the "hardness" issue. It is hard to stand on cement all day because it's hard. Of course, that is also true of tile, if you choose to lay that down over your subfloor. So, I quickly read 4-5 articles on the topic, and this is pretty much what they all had to say. The subfloor people and the cement people each argue theirs is superior; however, as you guessed, there are simply a lot more homes with wood subfloors in the US, and it's pretty much becoming the "assumed" floor of choice. So, if you live in the southeast, it seems like people should ask if your home is on cement or a wood subfloor, but if you live anywhere else, there just aren't that many around. I hope that helps! :-)