Q: Will plastic sheeting be an okay moisture barrier to use beneath hardwood flooring?
A: Avoid plastic sheeting on wood subfloors because it only serves to trap moisture and can lead to mold growth under the right conditions. For a wood subfloor you need a vapor retarder that allows some degree of permeability which allows it to “breathe.” Installation of a vapor retarder reduces the potential for moisture- or vapor-related problems, but won’t guarantee complete elimination of moisture. Asphalt felt or asphalt kraft paper are acceptable moisture barriers over wood subfloors, but consult your local building codes for specific requirements.