I feel like I've written about this a million times, but here goes....
When I moved in my property 8 years ago, I had tha bathroom retiled and the bathroom wall replastered. It's an exterior brick wall in a victorian house.
It then transpired the tiles were fixed directly to the plaster, with no membrane or waterproofing (it's a bath shower), so the tiles were leaking water.
I've since had the wall tiled again, with a water proof membrane (sheet, not painted), and that problem is now fixed.
However, over the past few years, I've had a persistent problem with the wall next to tthe shower, not holding pain, and bubbling/cracking shortly after it's painted.
Nothing seem to adhere to it. I've had a tile removed and the tiling checked to to make sure its not letting water through, and it's been checked for damp. I've redone and redone and redone the paint work over and over again, filled it, primed it, and painted it. I was using Matt emulsion, but even with bathroom paint, the same thing happens.
Someone said to me it could be the salt in the plaster.
There are no pipes in the wall, the shower comes from the bath taps which come up from the floor, I've had it damp checked, I've had the tiles installed with a membrane and rechecked. I've left it days and days before repainting again. Each time the paint cracks and buddles, and just chips off with a scraper.
I'm at all, but need a solution. The only thing I haven't checked are waster pipes from the flat upstairs, that go through that wall at the top (pictured)
Any ideas?