Your waterproofing strategy will continue with the installation of your shower walls inside the shower area. Each layer of the shower walls is intended to keep moisture from reaching the wood studs behind them and encourage it to either evaporate or lead downward into the shower pan, and exit into the shower drain. A strict back to front method of installation of your shower walls and a good understanding of how each layer supports the next will help you to accomplish an effective waterproofing strategy.
During normal shower usage, the atmospheric temperature differences between the air within the shower area and the moisture being introduced into it are going to produce vapor which will rise and settle as condensation. To protect from vapor reaching behind each layer, a vapor barrier is installed directly onto the wood studs around the entire shower area. Local and state building codes will differ, but in order to classify as a vapor barrier, the material must have a permeability rate of 1 or less. Common materials that are used are 15-pound tar paper and plastic sheeting with a minimum 4-mil thickness. An important rule to abide by is, never install a vapor barrier behind your tile substrate when you intend to apply a water resistant barrier over the front of the tile substrate.
The tile substrate will typically be the material you choose to hang onto the wood studs and over the vapor barrier. It will also serve as the surface to which your tile adhesive is applied and allows your tile to bond to. There are a wide variety of options to choose from, manufactured options will be comprised of a mixture of fiberglass mats and a combination of cement and mold resistant chemicals, or a tried and true option of floating cement to create your tile substrate. Either option may have a light consideration to be water resistant for their characteristic thickness and denseness for which vapor or moisture would have to travel through it, but it is important to understand that they are not waterproof on their own.
You can choose a water resistant barrier over your tile substrate to enhance the effectiveness of your waterproofing strategy. The options that are available to you are, a liquid membrane that is applied to the tile substrate, or a fiber based sheet membrane that is installed over the tile substrate. Both are proven water resistant barriers, and most even offer the advantage of being a vapor barrier as well. An important rule to abide by is, never use a water resistant barrier over the front of your tile substrate when you intend to install a vapor barrier behind the tile substrate.
It is very important to understand that there are various methods to achieving your waterproofing strategy over the installed shower walls. Each method is influenced by building codes, industry standards, and long lasting installations. As long as the method you choose does not veer away from these standards, you should expect the installation of your shower walls to be effectively waterproofed.
You will have a chance to learn from the mistakes that other homeowners have mede during pr after the installation of their shower walls. The alternative would be not learn about the proper methods and increase the likelihood your shower walls experiencing a waterproofing failure. The better strategy would be to see the methods that did not work and avoid those at all costs.