I just tore out old sheet vinyl in my bathroom to discover water damage on the underlayment. I started pulling out the underlayment to discover that the subfloor is also damaged. The damage is around the toilet and both corners of the tub. What is the best way to proceed?
Also, I was planning on laying 1/4" backerboard before laying my new ceramic tile. Will that suffice for an underlayment after replacing the rotted subfloor?
You will not be able to remove all of the bad plywood unless you remove the tub too and start over. It probably isn't necessary, especially if you have excess from below the room to add blocking. Once the new subfloor is in, 1/4" backer should be enough if you're installing ceramic or porcelain tiles.
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.