I have recently purchased a small commercial building with tile on most of the second floor. The tile is over concrete slab. During the cleanup process we noticed that water was leaking through and slowly dripping onto the first floor. It is hard to determine just where the leaks are as the water slowly trickles downstairs, it takes awhile it seems. I think water just slowly seaps through either the grout or the tile itself. Is there anything I can do to waterproof the tile upstairs, aside from ripping all the tile out and adding a waterproofing material and redoing the tile. The cost for that is just too high. Any help or advice would be appreciated.