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Insulated floating floor concerns about water vapor and termites

Debra | Posted in Energy Efficiency and Durability on

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.

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  1. Expert Member
    PETER G ENGLE PE | | #1

    No, there should be no problems with putting the flooring on top of Advantek subfloor on top of the Term barrier membrane. But your friend could also use the Term subslab barrier membrane (or really any other subslab membrane) which is probably cheaper. I'm not familiar with the Term products specifically, but their product line does include a family of physical termite barriers that also serve as air/water seals, flashings and such, so they do double duty. If your friend is trying to reduce use of chemicals, the Term family of products might be a good way to go.

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