A friend is looking for a way  to create an insulated floating floor on top of a concrete slab on grade, probably using the more affordable monolithic slab.  She’s near Ashville, NC (CZ 4).  I found one possible product that might help: Polyguard Term Floor Underlayment.  This 40 ml sheet is glued down to the surface of the slab, and provides water, vapor, and termite protection (in combination with other Term termite barrier materials).  Is anyone here familiar with this product, or has used it?

But would she run into the issue of creating a “moisture sandwich” in the creation of this floor?  Most of the affordable, easy to install floating floors are vapor barriers themselves.  This would leave the Advantech sheets between two vapor barriers.

The only other alternative I can think of, is if she can afford to have a slab created with separate stem walls instead of being monolithic. In that case, the insulation can be installed below and surrounding the slab (probably, in this case, with termite-resistant Rockwool, which I think is also more expensive than the GPS sheets in the first flooring example).  She’d like to avoid using insulation on the outside of the slab.

With the Term Floor Underlayment on top of this alternative slab, there shouldn’t be any problems with installing a vapor-barrier floating floor right on top of another vapor barrier.  Any thoughts or suggestions about her options?  Thanks.