It should be either waterproof foam board over wood or a waterproof membrane over cement board on the bottom plate of the wall. Then sit the wall in urethane and then waterproof the seam again with urethane on the shower side.
The waterproof boards are Wedi, Densheild, and kerdi board. The first two look like they have some sort of coating sprayed over them, giving them an even, but somewhat bumpy appearance. The Kerdi board is a smooth bright orange. All of these boards require the nail / screw holes to be waterproofed as well as the interior corners.
The purpose of waterproofing a shower is to keep your wall framing (and everything else outside of your shower) nice and dry and keep all the water inside so it can go down the drain.
Protect Tile Installations with RedGard Liquid Waterproofing and Crack Prevention Membrane - Duration: 5:57. CustomBuildingProd 26,770 views
Installing Waterproof Shower Wall Board. I used 1 5/8” screws to secure the HYDRO BAN board to the wall studs. The screws need to be countersunk flush with surface of the board. Make sure not to tear through the membrane.
Cement backer board provides a strong and moisture-resistant foundation for shower tile. Do not use drywall. Installing backer board is similar to installing drywall. You don’t need to cover your entire bathroom in backer board, just the wet shower area. In most cases, your cement backer board will butt up against existing drywall.
Shower Wall Boards & Splashbacks. Shower Panels and Shower Wall Boards (also known as bathroom wall panelling, bathroom wall boards or bathroom cladding) can be installed in any room of the house and are ideal for bathrooms, showers rooms, wet rooms, en-suites or even under and around units in a kitchen.
The 2” shower wall panels are ideal to build custom shower benched quickly and easily. The Wedi sealant is used to waterproof the areas where the shower wall panels meet and areas where there are screws. The Wedi shower wall boards are light and easy to work with and do not generate any cement dust.
Wedi Board: A lightweight ceramic tile backerboard. August 28, 2013adminWedi Board, Wedi Shower Systems. Wedi Board panels are the ultimate lightweight ceramic tile backerboard, designed to provide a waterproof barrier for walls and floors. It is also suitable for countertops bit should not be subject to extremely hot items.
“A waterproof membrane or vapor retarder membrane must be specified to prevent moisture intrusion and protect adjacent building materials.” ~B412 Bathtub or shower with prefabricated receptor. Cement board or Fiber-cement board.
Cement board is water safe, but it is not waterproof, so in my opinion the best way to prevent moisture penetration into the wall cavity, is to waterproof the entire surface with a liquid applied ...
A certain type of shower backer board is available which integrates the properties of the cement board and the moisture barrier. Georgia-Pacific's Denshield is one such product. An acrylic coating forms a sealed moisture barrier on top of a glass mat backer board.