The mixing valve is where your shower walls take the most abuse from water infiltration — and one of the spots most installers either skip or seal poorly. The KERDI-SEAL Mixing Valve seal is purpose-built for that exact penetration point.

It's a prefabricated section of KERDI waterproofing membrane with an over-molded rubber gasket that creates a watertight seal around the valve body. Embed it in your thin-set layer along with your KERDI membrane and the connection is continuous and code-compliant. Works alongside the KERDI Pipe Seal (for the shower arm/spout protrusions) — ideally you're using both.

Pro Tip: This is the piece most DIYers forget until they're partway through the tile layout. Order it when you order your KERDI membrane — it ships the same way and there's no reason to make a second trip. If water gets behind the mixing valve escutcheon, you'll be pulling tile in 5 years. This costs $30 and prevents that.