Proven Way to Extend ANY Schluter Shower Tray

Schluter shower tray installation is very easy.

But sometimes customization is needed. For example, when the existing shower is bigger than the Schluter tray sizes available.

So in this tutorial, you’ll see how to extend any Schluter shower tray using dry pack.

Let’s dive in!!

Why Use the Schluter KERDI Shower Tray

I get this question a lot.

The primary reason any DIYer or professional should use a Schluter KERDI shower tray is that it works.

First, prefab shower trays are sloped properly.

This means water will drain from the four corners to the shower drain.

Second, Schluter systems shower tray options come in different sizes.

This makes choosing the right one fairly simple.

Third, waterproofing the tray is easy because there’s already a waterproof fleece on the surface.

That said, many homeowners make several KERDI shower pan mistakes when waterproofing the transition to the walls, curb, and bench.

Finally, they’re affordable and the Schluter shower drain is, in my opinion, the best because it’s solvent welded and provides ease of use when setting shower tray tile.

But on top of all this, every Schluter shower tray can be cut down or extended…as I mentioned earlier.

Most Reliable Method for Extending Schluter KERDI Shower Tray

Entending or enlarging the Schluter systems shower tray is done with dry pack mortar.

What is a dry pack mortar?

It’s Portland cement and sand. One great pre-made option is Mapei 4-to-1 Mud Bed Mix – this can be found at most Lowe’s or tile supply shops.

Does Schluter approve this method?

Yes, the Schluter Handbooks shows this method when installing Schluter shower trays.

But here’s one annoying caveat:

Cure time.

Dry pack mortars require curing before any waterproofing can begin.

For example, Mapei recommends letting their Mud Bed Mix cure for at least 24 hours to allow water to evaporate.

Skip this step and you might sabotage your shower remodeling project.

Authoritative Step-by-Step for Making Schluter KERDI Shower Trays Bigger

While it’s easy to make any KERDI shower tray bigger, there are specific steps. So here’s the authoritative guide:

Apply modified thin-set to the substrate…this allows dry pack to bond
Mix Mapei 4-to-1 Mud Bed Mix…use 2 quarts per 55 pound bag
Pour dry pack over modified thin-set and tamp
Screed dry pack to accommodate 1/4″ of slope per linear foot
Smooth dry pack with steel finishing trowel and allow to cure
Apply Schluter ALL-SET to cured dry pack and waterproofed shower walls using KERDI trowel
Embed KERDI membrane into thin-set and smooth with 6-inch joint compound knife

Here’s a terrific short video to help you visualize the process