If you are constantly dealing with mold, moisture and musty smells in your home, be it in the bedroom, basement, or crawl spaces, you could benefit from a vapor barrier, professional contractors say.
the most important element in the design and construction of a concrete subfloor where a moisture-sensitive finish is to be applied is an effective, low-permeance vapor barrier placed directly ...
to provide evidence that moisture criteria are satisfied, or to establish expected floorcovering performance if the concrete slab has not been placed directly on a vapor retarder/barrier.” ...