In most cases, defects can be determined visually.

More serious recovery work may be needed for various reasons — this is the unprotected surface destruction (mechanical or natural), waterlogging of the base and its rot, damage to the fungus or insects. In most cases, defects can be determined visually. But sometimes damage to the eyes is not thrown, to find them, you should carefully examine the surface; Back, looking for voids, by the creak of floorboards or parquet to determine hidden defects of the base.