The tiles are still on the wall awaiting confirmation of which builder I will use - basically you can tell the plaster has blown by tapping but if it is like last time, I suspect they will come off really quickly as the plaster was soaking behind them. Just wondered if the theory of "water in the bricks" was a valid suggestion and if so the way forward. One builder has said the bricks need to be covered with a cement (?) type substance before the actual plastering is done as that will stop the plaster getting wet again. Does this sound correct?