Help, I want to tile my shower curb!

 September 14, 2022. 2:55 PM

By Denise Troiano and Joseph Smith

Shower wall installationsSo, you have figured out the shower pan and walls, but what about the curb?

Most people step over their curb daily and do not give it a thought; however, the curb is the location for many shower failures. There are many options for forming the curb, but an industry-approved installation method is crucial.

The old-school way is to create the form of the curb with two 2x4s. Then, wrap the vinyl liner that is used for the pre-slope around the 2x4s that form the curb.

Make sure to finish the curb waterproofing with PVC dam corners that are installed where the top of the curb meets the inside wall – this is a common point of water intrusion.

Once the curb is properly waterproofed, cut a piece of wire lathe to fit up, over and around the outside of the curb and then secure on the outside only with a staple gun; staple down at the bottom near the floor. During the final shower mud-bed installation, pack the mud up and around the lathe.

A common practice is to wrap cement backer board around the 2x4s. While this technique may be common, it is not an appropriate installation method. The reason for this is that you must screw the top and inside of the curb, as well as the outside. Once you puncture the vinyl liner, the shower is no longer waterproof.

Shower wall installations 2Even if you apply a liquid-applied waterproof membrane over the backer board, the shower will not be waterproof because the liner has been penetrated. Eventually, moisture can wick up and cause a failure.

Another popular option is pre-formed curbs, which are typically used when installing pre-formed shower pans where a traditional, primary pan liner is not required.

If using a liquid-applied waterproof membrane as your primary waterproof system, a pre-formed curb can be installed and then covered with waterproofing to ensure 100% protection (always confirm appropriate waterproofing options with the curb manufacturer). Many of these curbs are foam or high-density polystyrene; you can thin-set the tile directly to the surface of the curbs with a polymer-modified mortar.

Whichever curb you choose for your installation, make sure you do your research on the proper installation method. We are always here for you as well. Call MAPEI Product Support at (800) 992-6273 to discuss your installation with an experienced technical representative.


Denise Troiano
Denise Troiano brings 24 years of experience in the tile, stone and installation products industry to MAPEI. Working with manufacturers, retailers, designers and installers during this span allows her to answer a wide range of questions from homeowners and industry professionals.

Joseph Smith
Prior to coming to work at MAPEI, Joe worked in the tile industry for 40+ years as an installer, and for 38 of those years he owned a contracting business. He now uses that real-world experience and knowledge to help customers while working as a Technical Support Advisor for MAPEI.

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