What should I use to waterproof the walls of my shower?

For an Ella shower, the walls are kept waterproof by three layers working together rather than by a single product: a finished wall surface, either factory-finished wall panels or tile, that comes down over a flexible glue-up flange bonded to the edge of the base with 100 percent silicone, and a bead of silicone at every joint. The flange is the piece most people have not seen before, and What is a shower flange and what does it do? explains its job: it catches water that runs down the wall and sends it back into the shower instead of behind the base. Get those three layers right and the wall line stays dry through the expansion, contraction and floor settling that a rigid seal cannot follow.

Layer One: The Wall Surface

The surface the water hits is the first line of defense. Ella offers factory-finished panels for it, and tile is the other option.

• Ella wall panels. Ella's own shower wall panels come down over the flange the same way tile does, and the flange article notes that the same kit is used on shower bases and on walk-in tubs.
• Cultured marble travertine panels. The second video shows these panels, made from a natural quartz and granite composite with a gel coat surface. They come as eight, six or four panel surrounds that one person can carry and install, and they can be glued over drywall, plaster, painted walls, Durock or even existing tile. The edges are factory finished for seamless joining and can be trimmed for a custom fit.
• Tile. A three-wall alcove with a tiled surround takes care of waterproofing on three sides. Existing wall tile that is sound and properly sealed can stay, with your installer confirming its condition.

Whichever surface you choose, it must run down over the flange and onto the deck of the base, never stop above it. Tile that stops short of the flange, a flange that does not overlap the fixture edge, or corners left uncaulked are the finishing gaps that put water at the corners even though the fixture itself is sound.

Layer Two: The Flexible Glue-Up Flange

Ella bases and tubs have no molded tile lip, so the flange is added at installation, and it is a flexible membrane rather than a rigid plastic strip. The residential kit contains one roll of 4 inch wide waterproof membrane with an integrated 1 1/4 inch siliconized adhesive strip, a spreading spatula, a cardboard alignment guide and two alcohol cleaning tissues. The pink portion is the membrane that bonds with the silicone; the rest of the strip is a cloth-like material that gets tiled or paneled over. The strip is reversible, with a pink side and a red side, and which side faces out depends on whether your fixture already has an integral flange. The Glue-Up Tile Flange Kit walks through the box, the lengths and the orientation.

Choose the length by measuring the wall perimeter at deck height. The 132 inch strip is the right pick for a 60 by 36 shower base, the 124 inch kit suits most Ella walk-in tubs in a standard 60 inch three-wall alcove, and a contractor bulk box holds a 164 foot roll without the spatula, guide or tissues. If you are between sizes, the bigger strip is fine. Because the strip is flexible, it can go on after the base is set. The first video shows the kit contents and how the alignment card is rested on the ledge of the base to mark the strip position on the walls of a two-wall or three-wall enclosure before the base goes into its final position.

Layer Three: Silicone at Every Joint

The flange only works with 100 percent silicone, and the kit guide calls for a neutral-cure product. The video explains why: the siliconized membrane reacts with the applied silicone and chemically bonds to it, which is what makes the seal hold through general expansion and contraction and routine floor settling. Clean the fixture edge with the alcohol tissues, bond the flange so it overlaps the edge, run the tile or panel down over the flange and onto the deck, then silicone every joint, including where panels meet each other and where an end panel meets the wall. How do I tile over the tile flange on a walk-in tub? is written for a tub, and the same flange approach applies to a shower base.

Order of Work

1. Set the base, connect the drain, and confirm it is sound before any wall is finished. On a walk-in tub that means leveling with every leg bearing on the floor and completing the water test first, because a leak behind finished walls is far more disruptive to fix than one found with the walls open.
2. Mark the strip position on the walls with the alignment card, as the first video shows.
3. Clean the fixture edge and bond the flange with 100 percent silicone so it overlaps the edge, with the correct colored side facing out.
4. Install the wall surface so it comes down over the flange and onto the deck.
5. Silicone every joint and let it cure before the shower is used.

If the Shower Shares a Room with a Walk-In Tub

In a wet room the acrylic shell and exterior panels of a walk-in tub tolerate splash and humidity, but the compartment behind the access panels must stay dry because it holds the GFCI receptacle, the control boxes and the pump cords. Installing a Walk-In Tub in a Wet Room recommends pointing the shower head away from the seat end of the tub, placing a partial wall or glass screen between the shower and the tub apron, and sloping the floor toward the room drain rather than toward the tub. A three-wall alcove with a tiled surround takes care of three sides, and the deck-to-wall joints are finished with the same flange and silicone described above.

What Is Not Part of the System

There is no separate waterproofing membrane to spread over the base or up the fixture edge; the flange membrane is that layer. A rigid plastic flange is not a substitute either, because it cannot follow the movement the flexible strip is designed for. If your fixture came with no lip and the installer is unsure which strip to use, My Tub Has No Tile Lip. Which Flange Do I Use? covers the current kit and what to send when you open a ticket. If you are unsure which flange length fits your layout, or the walls are already partly finished, open a ticket at ellasbubbles.com/support with your model, a sketch of the enclosure with wall lengths in inches and a photo of the fixture edge at the wall, and your Ella dealer or the team at (800) 480-6850 will confirm the kit and how to place it.

Watch: Installing a Glue-Up Tile Flange: Step-by-Step | Ella’s Bubbles with chapters and a full transcript.

Related Guides

• Acrylic 6-Piece Wall Panel Kit: Size, Shelves, Thickness and How It Compares to the 3-Piece Surround and SMC Panels
• Cultured Marble Shower Wall Panels: Stock Sizes, Cutting to Fit, and Finishing the Edges
• How do you install and seal tongue and groove PVC shower wall tiles?

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