I have a building that I recently purchased. The previous owners started to replace a damaged area (1/2 the floor) with an underlayment that is exactly equal in height to the remaing commercial grade tile. The remaining commercial grade tile is really stuck down! It has some old chips out of it, but it has apparantly been this way for years. Can I use a floor leveler to fill in the old chunks that are missing and then lay tile over the tile and onto the underlayment that was layed a couple years ago? It really does appear that this tile is down very very tight! It has had lots of traffic and pool tables on it! Someone at a floor covering store thought it would be ok if it was the Armstrong commerical stuff, but not ceramic. Why not ceramic? Or does anyone have any other ideas for a good commercial floor that would work under these circumstances?