I've been following the show "Holmes on Homes" lately, and he has some interesting points about building in a basement.
Or, for that matter, building atop concrete at all!
First off, not all basements are the dark, dank, deep pits you might imagine. Indeed, it seems that, in most cases, the slope of the land results in one wall usually being pretty close to 'grade' level.
The basement remodel begins with installing a 'French drain' around the perimeter of the house, slightly below the level of the basement floor. This drain is intended to keep water from accumulating around the basement at all.
The basement wall is sealed on the outside with something that resembles tar or pitch, then a 'waffle' pattern plastic sheet is set against the wall. This, I believe, is to prevent the dirt itself from damaging the tar coating.
Inside the basement, Mike Holmes parts with 'conventional wisdom' and speaks against placing any manner of plastic sheet on the floor or walls as a 'vapor barrier.' His opinion is that these simply trap moisture, and lead to a mildew issue.
Rather, he sets rigid foam insulation directly on the concrete, and tapes the seams. This provides a 'vapor barrier' on the 'warm' side of the foam. He does encourage the use of radiant heat in the floor, in part as this will dry out any moisture that may get there.
