Gut the shower stall down to the studs. You may need to remove the shower pan and ceiling, as well. Do not put down any plastic because this can trap moisture and lead to rotting. Instead, use a product that you can paint on to help prevent moisture. Choose a vapor barrier to install and introduce according to manufacturer directions. If you fail to install a vapor barrier, you might grow mold and mildew as moisture from your shower escapes through the tiles and into walls tile. Improperly installed rustic tile and grout can allow water vapor to pass into the space behind.
When installing a vapor barrier on an exterior wall marble tile, it may be helpful to seal a plastic vapor barrier to the concrete floor but not all the way up to the top of the ceiling. With insulation improperly installed, or in colder climates, there’s a chance that condensation that forms behind the vapor barrier will cause the framing members to rot. In order to avoid that possibility, install the vapor barrier with space to spare so that the gap behind the vapor barrier can breathe. Use a roll on product, such as Red Guard.
Wedi boards are another option some consider even better than cement tile. If you choose a membranous barrier such as Trugard or Kerdi, you can install plain old drywall tile or you can just install a cement tile instead. Put up a sturdy cement tile backer. Putting up wall marble tile is just like putting up drywall. You cut it to fit using a grinder with a diamond bit, and then screw it to the studs. Leave a 1/8″ gap between panels and then a very small space between the shower pan and the bottom of the backer so that the two don’t squeak by rubbing together.
Use a hole saw with a carbide bit to cut the holes where the shower head and handles would come through. Make the small tile flush with the tile lip of your shower pan by using shims behind the board to bring it out to the desired thickness. Make sure to use composite shims. Use 100% silicone caulk to seal the seams between the panels and then apply the silicone behind the board on the stud. Add some seam tape between the panels as well.
Lay the drywall. If using crown molding near the ceiling, lay down 12 to 18 inches (30.5 to 45.7 cm) of drywall instead of cement tile. Nails used to fix the crown molding in place will not travel through the tile; you’ll need to use moisture-resistant drywall such as greenboard in order to take the nails and affix the molding.
Feather any edges with seam tape and thin set mortar where the backer board meets the wall tile. If there’s a gap between the backer board and the wall tile, you’ll want to use seam tape and then feather the gap with thin set mortar so that it appears as one continuous back. Remember that the seams must remain tight with gaps 3/16″ or smaller.
Paint a water resistant primer over any areas you intend to tile. After you’ve feathered the edges to remove the gap, apply a high quality water resistant exterior primer over the feathered wall tile and backer.