We've recently had a shower control unit recessed into our external bathroom wall, taking out some of the brickwork. The hot and cold pipes have also been cut into the wall. The work was then covered with nice (quite expensive) tiling. After only a couple of months, the tiles around the control unit and pipe to the shower head started to bulge and crack. Our builder came and looked at the damage, took the tiles off and said that there was no leak causing the bulge - he thought it was due to movement. Although there is some movement in that part of the house (we're on London clay!), the way the bulge is just around the control unit and pipe makes me think it's some sort of insulation problem. He replaced the cracked tiles with new ones, but after only a few weeks more, the same problem recurred, worse if anything! Anyone got any suggestions or think of reaons for this. We've spent a load of dosh on it and it's looking crap after a very short time... There's no evidence of movement externally. Any help much appreciated!