I am wanting to tile my master bath.
When I pulled up the old linoleum flooring, it was particle-board. I've read nightmares about tiling over particle board so I'm planning on replacing it with plywood + cement backer.
This is the 2nd story of my house and the walls are sitting on top of the particle-board. On the exterior wall, I was planning on just cutting along the length of the wall as close as I can get to it and reinforcing the new plywood from underneath between the joists (which run perpendicular to the exterior wall).
However, on the interior wall near the toilet, there has obviously been a previous leak causing damage to the flooring under the wall and causing a gap (just over a 1/4in). The level of the floor here has definitely sunk (revealed by using a level) to this point.
The other side of this wall is another toilet in another bathroom which I do not plan on renovating (yet) since it is the only other bathroom in the house.
How do I fix this?