This prevents the moisture present in the concrete from penetrating and damaging your floor. On underfloor heating and on concrete subfloors, a 0.2 mm thick age-resistant plastic foil (PE foil) should be installed with a 20 cm overlap, alternatively a combi foam can be used with combined step sound attenuation and moisture protection. It is important that the subfloor is properly cleaned so that no mold can form under the plastic.