Expert: Dan Griffin - 11/10/2007

Question
for shower walls torn down to the studs what is the best way to build back up for tile. just backerboard, plywood or greenboard underlayment??

Answer
None of the above.
I think you should re-perform the shower pan if you have torn the rest of the shower down to studs to really do this right.  The best step by step explanation would be here:
http://www.johnbridge.com/serv02.htm  Find his explanation of Kerdi shower.

You can also do a good job with concrete backer board.  YOu  should install a vapor barrier between the studs and the CBU with this system.  Most professionals do not recommend visqueen, they prefer tarpaper or heavy mill PVC.  Great attention must be paid to the shower pan and water proofing the connecton of walls to base as this is the failure of most installations.  Read John Bridge's description at the same web site.

Do whatever you need to do to insure that the walls are flat.  All tile work goes better and looks better when the walls are flat.