Moisture barrier liquids.

I’d like to go over the subject of the invention of moisture barrier liquids, which has revolutionized the way we do bathroom remodels.
We use the RedGard product which is available thru Home Depot. There are other companies that are also making these liquids and they have not only become very popular but are required by many city code enforcement departments. Let me explain why these liquids are now so important in the bathroom remodel process.
When you take a shower, a small percentage of the water that runs on the shower floor and the walls gets behind the tile and grout. The amount of water that gets thru of course depends on how long and how much water is being used as you take a shower.
Even thou green board is still sold and used, it eventually breaks down from the exposure of water. The old shower floor liners eventually deteriorated after many years of use and the shower floor starts to leak water once that happens. Today we have cement board products, like Durock, for the walls that will not only survive from long term water exposure but that they are highly resistant to mold growth. The new shower liners made from a combination of PVC and rubber are the best in the market now, offering a long lasting, mold resistant and flexible product to work with. We use the Oatey liner which is available thru Home Depot.
However, the water was still getting past these new wall boards and the water was getting to the studs and the adjacent wall boards. This was still causing mold growth behind the walls. Another problem was when shower seats were installed, made from pressure treated wood or even from concrete block, the water was still sitting inside the frame of these seats causing mold growth. Eventually, for shower seat installations, the shower liners had to be extended behind and around these seats past the height of the seat and the seat itself needed to be covered by the liner causing more work for the installer and more expense for the customer.
Now, what we use is the PVC/rubber liner on the shower floor.  For the walls, the seats and niches we use two coats of RedGard. This product is like a liquid rubber that also adheres to the thinsets/cements we use to install wall tile. Once the water gets past the tile and grout, it runs down the wall on top of the RedGard and eventually runs to the shower liner and to the drain. On the bathtub walls it runs down the RedGard and onto the bathtub edges and if your bathtub is pitched properly it goes to the drain.