The subfloor should be dry, level, solid and clean.. Old wooden floors, concrete, self-leveling floor compound, etc. can be used as a subfloor.
Please note that the textile floor coverings are not suitable as underlay material..
Before installation please ensure that subfloor is sufficiently dry (see the section "Waterproofing"). Carefully remove any dirt from the subfloor because it can become the environment for reproduction of harmful microorganisms. MAKE SURE THE SUBFLOOR IS LEVEL.
Using a straight ruler at least 2 meters long carefully check the level of the subfloor in all area of future installation. Any deviation between the subfloor and the straight ruler should not exceed 2 - 3 mm per 2000 mm length. If required, the subfloor should be leveled and sanded to meet these requirements. Old wooden floors or tile floors joints should be checked and if necessary should be fixed with nails or self-tapping screws or leveled by sanding, installing plywood or applying filler coat.