Our 15mm Impact Tiles - Designer Series can be placed over the concrete no matter the age. If the concrete is clean and fairly flat, you should have no issues. If you do have a moisture issue, it may be pertinent to place a vapor barrier between the flooring and the concrete. This will help to eliminate the growth of mold and mildew underneath the tile and prevent sweating. If there is no moisture issue, then a vapor barrier is not needed.