We were asked to make some repairs in a bathroom.
Water was leaking through the ceiling of the kitchen directly below the bathroom. After removing the bath, it was clear that water had ingressed through the silicone seal and had completely disintergrated the wallboard and rotted part of the floor.
We removed a section of tiling, cut the soaking wallboard out, replaced it with new board, replaced a section of floor, applied a waterproof membrane and replaced the bath. We the re told the wall and made good.
You can see in the photos the process.