I have just been stripping tiles and discovered a hole in the inner wall, the outer wall has an air brick but the inner wall appears to be missing two bricks at least. Firstly, structurally is the building ok if I don't fill the gap and secondly, I assume I should fill the gap and if so, how? I basically want to tile the wall, it is in the bathroom, so what do I need to do?
Many thanks.
Many thanks.