I have received several different opinions on what wall prep needs to be done above a shower stall. What I want to do is put ceramic tile from the top edge of the shower stall to the ceiling. What is there now is wallpaper over sheetrock. Not sure if it is greenboard, but knowing the builder, probably just regular sheetrock. I know I need to remove the wallpaper, but after that I have been told 1) I have to put cementboard, 2) replace the sheetrock with greenboard, and 3) put the ceramic tile on the sheetrock.!! The top edge of the shower stall is at least 78 inches high so the tile would start there and is not likely to get soaked. It would be 3 to 4 courses from top of stall to ceiling. Advice would be appreciated.