Online Blog > 01/17/2013 - Superior Tile Shower Construction in Sandpoint, Idaho > Next Entry 01/18/2013
At Scott Herndon Homes, we enjoy the privilege of building custom tile showers for our customers. When these opportunities arise, we employ a superior method of waterproofing your shower using Kerdi by Schluter Systems. I will summarize its advantages as compared to the traditional shower pan liner and show its application through a shower we just completed in a master bath in Sandpoint. First, my last post on Correct Tile Construction shows you a diagram of a traditional tile shower pan. Even though a properly constructed pan will be waterproof, there is a substantial amount of mortar and tile material that can be exposed to water for a length of time. Specifically, if and when the top layer of mortar (under the tile but above the pan liner) gets wet, it will usually remain wet a long period of time. I guarantee that in this material is some mold food. Moisture and mold food mean you will have some mold or mildew. And mold means you will have some smells and maybe even some health issues if you are particular susceptible to mold toxins.
The Kerdi shower system is altogether different. Kerdi is a polyethylene membrane that is water and vapor impermeable. It is enmeshed with a fleece which allows a Portland Cement based thinset mortar to adhere to the membrane. The tile is adhered directly to the membrane using thinset. The membrane is applied to the shower floor over the pre-sloped dry pack mortar bed, and there is no additional mortar bed installed over the Kerdi. This eliminates a substantial thickness of mortar that would otherwise be a wet environment harboring mold growth. Kerdi comes with its own unique drain that also has a fleece embedded bonding flange to which the Kerdi membrane is overlapped and is bonded with thinset mortar. There are no weep holes to get clogged. Kerdi membrane is also run up the walls of the tile shower. A Kerdi band is applied to the corners and to the floor to wall transitions, creating at least 2" overlapping of all Kerdi membranes. This 2" overlap bonded with thinset mortar creates a waterproof connection from sheet to sheet. The entire shower is vapor and water impermeable below the tile and grout. The only thing that will ever see water or vapor in the shower is the tile, grout and the drain. Then, in between uses, the tile and grout typically dry out, since there is no substantial depth of water penetration, and where there is no wet, there is no mold. And, where there is no mold, there is no mold smell. And, there is no mold sickness
Here is a picture of the drain with layers peeled away:
And here is a diagram of the shower cross section: