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  • Writer's pictureZack Jurkowski

How To Waterproof A Shower

When it comes to bathrooms, the shower can often be the single most expensive unit in the bathroom. We're not talking about a bathtub with a shower curtain. We're talking about an alcove or corner shower with glass doors. Even on the cheap side, they're usually the most budget-intensive standalone unit.

A standard toilet can be had for $100-300. An economical vanity and faucet can be had for as little as $250.

What Makes A Shower?

A shower includes wall boards, waterproofing materials, tiles, a shower fixture, a shower head and glass doors. While a toilet is installed by a plumber, a shower requires carpentry, plumbing, sheathing (walls), waterproofing, tile-setting and fenestration (glass doors). There's also the shower base, itself. A common option is the white acrylic pre-fabricated base. The most popular option is a tiled shower base. The trends have been leaning towards tiled bases, barrier-free with wall niches and even benches.

These trends are proving more than ever just how important proper waterproofing is for your shower.

(Disclaimer: This is not an ad, sponsorship, and is not affiliated with Schluter... I just really love their product!)

Tiles Are Not Waterproof

Neither is grout. Caulking won't save you, either. (No matter what your handyman thinks.)

Tiles may be glazed on the outside, but the core and edges of the tile are prolific at retaining water. The grout is a cementitious product, comprised mainly of Portland cement. This allows it to absorb water. The water travels through the grout, where it gives way to the core of the tile and the mortar bed which holds your tiles on the wall, through capillary action.

This effect is greatly amplified on shower floors, where water is allowed to stand and create a saturated bed. Water must be kept in the shower and out of your home to prevent structural decay and mold growth.

Let's jump into the basics!

How to waterproof your shower

There are two popular methods that you can use to waterproof your shower.

Mortar Bed

A traditional way to waterproof your shower base is using a vinyl liner under a hand-packed mortar bed for the drain. Often called "mud bed", this is the "old-school" way to do it. It's labour intensive and leaves a lot of room for error. If it leaks, it has the tendency to leak slowly, rotting the substrate over time.

Waterproofing Membrane

The second way is by applying comprehensive waterproofing system to your walls, wall penetrations and shower base. There are several brands that offer waterproof membranes, impervious panels and pre-formed shower pans. By far, the most popular and readily available brand at professional supply houses is Schluter.

What Is Schluter Kerdi?

Schluter Kerdi is a collection of waterproofing membrane components. Waterproofing a shower has a few steps:

Waterproofing the walls

This allows water and vapour that travel through the grout joint and into the mortar bed to travel down to the pan

Waterproofing the corners

This creates a seamless path for water and vapor to travel across. Any water traveling down the walls will pass over the corner before hitting the pan.

Waterproofing the pan

Since the pan is a horizontal surface with the potential for standing water, it is of utmost importance for it to be completely impermeable and lead to the drain.

Waterproofing the drain

The pan waterproofing integrates to the drain waterproofing with a multi-layered redundant flange system to ensure any water that makes it's way past the tiles can travel directly to the drain. The proprietary composition of the product ensures that any water remaining in the mortar bed can evaporate between uses due to it's virtually inexistent permeability.

Kerdi was developed as a waterproofing membrane to be used in conjunction with ceramic and stone tile coverings. It's a pliable, sheet-applied, bonded waterproof membrane and vapor retarder.

Why Schluter Kerdi is the best choice for your bathroom

Why use Schluter Kerdi? Here are a few key benefits of using this product:

-Protects from water damage and mold growth

-Easier to install than traditional waterproof membranes

-Reduces installation time compared to other products

-Provides a smooth surface for tiling

-Allows tiles to be installed directly onto substrate

-Comes backed with a guarantee

The Schluter Kerdi waterproofing membrane has become a trusted brand among homeowners, designers, and contractors. They have been around since 1975, and the system is comprehensive. In my professional experience, it's a bullet-proof system.

To protect your bathroom from leaks and water damage, it's important to install a quality waterproofing membrane. With all of the benefits we've outlined above, there's no reason not to choose KERDI when installing new showers!

What are some of the reasons why you would want to waterproof using Schluter Kerdi? If you have any questions, drop me a comment below and I'll do my best to help out!


Montreal Contractors is a qualified company, holding an active bonded license as a General Contractor and Specialized Contractor with the Régie du Bâtiment du Québec (RBQ License: 5767-5480-01), ASP Health & Safety Certification and a $2M liability policy. Our employees have all passed background checks, are registered with CNESST and have their ASP Health and Safety certification.

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