Ok, long story, but I'll try this: Short version - Can I replace a section of wall behind the tile where my shower fixtures are located without ending up redoing my entire bathroom? Long version - About two weeks ago, I was cleaning the tile in the shower and two tiles broke loose. There was mold/mildew behind the tiles growing in the grooves in the mastic base behind them, indicating a leak. I cleaned the visible area, but noticed that it felt really soft. I was concerned, but stuck the tiles back in temporarily with a little tub caulking. The following week, cleaning the tub again, and the tiles came out again, this time taking adjacent tiles with them, revealing more moldy/mildewy mastic. I also found a small hole in the mastic that goes right through the wall, through which I learned that the wall itself seems to be nothing more than cardboard (or some sort of moderately soft pressed or processed cellulose board). I've tried contacting a few local contractors, but none of the ones in the phone book have voice mail and the one guy I did manage to get ahold of gave me this grumpy old man vibe and told me that I'd be better off doing the repair myself and not bothering him. I'm hoping there is some miracle way to replace the offending part of the wall without turning this into a "onion peel" project where every task completed just results in twice as much repair in the long run. I haven't seen the studs behind the wall, but I fear that they might have something growing there as well. If there is, how do I get rid of it? Even if there isn't, how am I going to repair the tile when the wall is fixed without having to rip out all of the rest of the tile? If I have to end up replacing all of the tile, and I can only work on this on nights and weekends, and I have no earthly idea what I'm doing, how long will it be before I can take a shower again?