I'm in the process of a wall tiling job in a half bath. No shower or tub. Can I safely tile using organic mastic over the existing drywall, which has been covered years ago with some type of cement like textured surface? I plan to use 3 x 6 porcelain subway tiles. I have been told that the weight of the tile if placed directly onto drywall will cause the paper backing to pull away from the drywall and the tile will fall off. Is this true? And does the fact that my wall is covered in textured cement offer some strength and protection for this installation?

 

Never heard of "organic" mastic, but if it's package says it is made for your type installation, then go for it. You may have a little trouble getting a perfectly flat install, depending on how much texture you have on the walls. It is ideal to install tile on concrete backer underlayment, but since you don't have any moisture to deal with, you may be ok with it. Just check your texture depth.

 

Mastic is a good choice for this application but you might want to investigate the 'cement like textured surface" to find out exactly what you are dealing with. Any chance it is plaster over blueboard?