Celebrating a Lesser-Known Role of Hamilton: Father of the Coast Guard 2 Â· 1 comment President Trump to give keynote speech at US Coast Guard Academy in May 2017.
First, You don't Tile over Drywall in any case in Bathroom area exposed to Moisture etc.( you may have to remove existing drywall& install cement board, around that area for better results of tiling. Second. The drywall should not be, less then Blue Board for all areas except Shower or bathtub tiling.
That is true - you cannot tile over plaster, if that's your plan. You would have to remove the plaster and replace it not with drywall - run from a contractor who says that! - but with cement board. The problem otherwise is that grout is porous and any slight crack will cause moisture - and mold - on any other surface.