Working around a tub or shower requires special wall board materials and even some special considerations if it is an insulated wall. And no wall board material capable of absorbing water should come into direct contact with the tub itself.
The Canadian Building Code will be changing in 2010 to require membranes behind tub and tile showers. For videos and other information about the best of these membranes, the Kerdi membrane, I invite you to visit www.SchluterHouse.com, click on the bathroom and then on the shower for a wealth of information all related to tile installation.
Learning Curve 13