Any existing subfloor must be even, dry and sufficiently
stable. Larger depressions should be evened out using standard commercial
fillers. The surface of the subfloor should be free of cracks without any breaks
or tears. Loose subfloors or insufficiently stable subfloors (PVC-/ textile
flooring) need to be removed. Mineral subfloors/screed need to be sufficiently
dry. It is always required to have the subfloor that will accommodate the
sub-structure and the measurement of residual by an expert/flooring specialist
(this should include professional measurement of residual moisture levels).