OK, so the fun of life in this bathroom as of late is that I got to take the tile off the wall, only to find out that, guess what? There's another layer of vinyl tile on the plaster. So, here are my questions:
1. Do I really need to remove all the tile that's right up against the plaster or can I just remove enough to anchor the drywall I'm going to put in over it to affix the backer board to?
2. Do I even need to bother putting drywall in place over the tile or can I just put in backer board?
3. If I do have to put in drywall, after I tape it would it make sense to prime it just to add one layer of protection between the backer and the wall (I was given this advice if I end up having to replace the subfloor in the bathroom just to provide one more layer of protection between the backer board and the subfloor)?
My best advice is to remove all the old wallboard and put cement backerboard up in the tub/shower surround. A thin plastic dropcloth placed over the studs before the cement board goes up will protect the wood from water intrusion, should that happen. Tape the seams and corners of the cement board with fiberglass mesh tape and apply a thin coating of modified thinset over the tape. After it dries a rubbing brick can smooth over any rough edges. Drywall can be used in other non wet areas of the bathroom, just not where the wall is constantly exposed to water spray.
