The floor supporting this customers balcony was going rotten – nothing was visible from on top, but you could see the damage being done by water getting under the tiles in the garage below.  I had to take up all the existing tiles (got a nasty surprise here as there was another layer of tiles underneath) and replace the rotten joists and flooring.  New slate effect porcelain tiles were then laid onto a special backing board and a new chrome gully fitted to ensure everything stayed water tight.