About 10 months ago we had our bathroom re-tiled with 15.5"x9.5" tiles over existing (smaller) tiles. We have now noticed that a number of tiles in random places on the external walls (brick) have numerous hairline cracks and are bowing outwards, although the grout between the tiles is still intact. When tapped there is a hollow sound as if the tiles are no longer fixed to the wall. There is no problem with tiles fixed to the internal walls (breeze block).The tile fitter is blaming faulty tiles whereas the tile supplier is blaming the installation. I do know that during the installation the fitter had to use thick layers of adhesive due to the walls not being true.
Any thoughts on what is to blame? We are stuck in the middle and don't want to end up paying for the re-tiling!!