So I am wanting to turn my tub only area into a tub and shower and because of this I am wanting to tile the entire surrounding area with tile.
The big question I have is if the wall has latex paint, slightly glossy, and I put water-proof membrane over it, is that strong enough to hold in the wet area? I have coated a small area and the hold it strong, it takes a sharp edge to break the membrane, can't just pick at it with my nails, and it doesn't peel off the entire area after breaking it.
The water proofing Mapei Mapelastic™ AquaDefense.
The wall underneath is solid, I can't say it is a CBU but it is some mix of hard materals, very corase, as it ruined my metal saw blades fast when I have to move and outlet over.
Best Answer
I have applied thinset over paint many many times. I mean they have waterproofing paint (redgard) now and you thinset over that. Now the question is did the paint cure and does it have a good bond to the surface? If you don't know that then mix a little thinset, put up one tile (where you will eventually want it), and test it out. If it is solid the next day then you are good to go.