Our water proof showers start off with the standard PVC shower liner & drain system, and 1/2" cement wallboards for the entire shower. Then we cover the bottom half of the shower walls with a fabric waterproof membrane as well as the shower subfloor and curb. The tile is installed directly on top of the membrane so that any water that passes through the tile and grout stops right there. This causes the wallboards and the shower subfloor to remain dry and solid for the life of the shower as well as no mold ever! We guarantee this double layer membrane to be leak proof for the life of the bathroom.