Waterproofing Showers, Part 4: Sheet-Applied Membranes Done Right

When it comes to water management details in home construction, no other assembly faces as much annual “rainfall” as the shower. Add in soaps, oils, gels, and other surfactants, and shower water has far greater penetrating power than natural rain. As such, it’s crucial to correctly install water-management details in a shower, among them sheet-applied membranes.


What You Need for Shower Waterproofing Using a Sheet-Applied Membrane

The use of sheet-applied waterproofing membranes has grown in the last 20 years, with several manufacturers in the market.

Waterproofing Showers, Part 4: Sheet-Applied Membranes Done Right

Some brands, such as Schluter Systems’ Kerdi-Board and Triton Waterproof Backer Board, have laminated the membrane to tile backer panels, streamlining installation and requiring only that you treat the seams, joints, and fasteners with a recommended waterproof membrane tape. There are also complete shower kits that include pre-sloped shower floors and corners, as well as pipe or valve escutcheons, to further ease installation and material compatibility.

It is possible to cobble together a waterproofing system using a combination of brands, but I recommend the complete-kit approach to get the full benefit of a manufacturer’s warranty.

It’s critical to read the documentation and the warranty that comes with the kit and to follow all of the manufacturer’s installation guidelines. Most provide great warranties, and some are even better if you use one of their certified installers.

Doing It Right: Correct Installation for Sheet-Applied Waterproofing Membranes

Correctly installing a sheet-applied waterproofing membrane requires attention to detail and a commitment to quality assurance, namely:

For shower assemblies, my rule is simple: If the shower can’t be used prior to installing the tile or solid surface finish without leaking, it isn’t ready for the tile installation or solid surface finishes. A properly installed waterproof membrane shower system can be used without any tile installed. It may not be pretty, but it would be functional.

Graham Davis drives quality and performance in home building as a building performance specialist on the PERFORM Builder Solutions team at IBACOS.