What is a shower dam and when do you need one?

A shower dam is a collapsible rubber strip that runs across the open entry of a barrier-free shower base and holds the water inside the stall, doing the job a curb does on a stepped shower. Ella also calls it a collapsible rubber dam, water retainer, flexible shower dam or collapsible threshold, and it comes standard with Ella's roll-in barrier-free bases. You need one only when the base has no threshold at all; a low-threshold base keeps water in with its molded step. What is a roll-in shower and how does it work? describes the stall the dam belongs to, and this page explains how the dam works, which bases need one, how it is installed and what to ask for when you order.

How a Shower Dam Works

Without a curb, something else has to keep the water off the bathroom floor. The dam is a flexible, compressible, waterproof rubber strip fixed across the open entry. When a wheelchair, walker or shower chair rolls over it, the strip flattens under the wheels, and once the wheels pass it springs back to its original shape, so the stall holds water the way a curbed shower would. The video on this page shows exactly that: the dam compressing under a wheel, returning to shape, and then holding water inside the stall while the shower runs.

The dam attaches with strong, water-resistant self-adhesive tape, so there is no drilling, and it is made for exclusive use with a barrier-free wheelchair accessible shower base. It ships with the roll-in barrier-free bases rather than being an add-on you have to remember, and it is finished with plastic end caps and a thin bead of silicone so water cannot creep under the ends.

Barrier-Free Versus Low Threshold: Which Bases Need a Dam

Barrier-free, zero-threshold and curb-less all describe the same thing on an Ella base: the entry is flush with the floor, so a wheel or a foot passes from the bathroom onto the base without being lifted. A low-threshold base has a short molded step instead. That step keeps water in on its own, which is why the low-threshold acrylic and cultured marble bases have a molded threshold instead of a dam. The threshold figures published across Ella's shower pages line up like this.

What the differences mean: the lower the entry, the more the design relies on the floor slope, the drain and, at zero threshold, the dam to keep water where it belongs. A 3/4 inch step and a flush floor can look alike in a product photo, which is why the threshold figure on the spec sheet, not the picture, should decide. If you would rather have a small raised edge than a dam, Ella offers the three-inch step-in threshold. If the person bathing stays seated in a wheelchair or shower chair and needs to roll straight in with nothing to cross, choose a barrier-free base and use the dam. How Deep Is a Shower Pan and Does Depth Matter? explains why threshold height, not depth, is the figure that matters on a shower base.

Installing the Dam

The dam goes in after the base is set, and the video walks through every step in order:

1. Measure precisely and lay a line of tape on the base as a guide.
2. Clean all mounting surfaces thoroughly with alcohol. This is the one rule that cannot be skipped, because the adhesive will not bond to a surface that has not been cleaned.
3. Measure how much material you need, mark it and cut carefully.
4. Insert the plastic end caps as indicated and apply silicone to any gaps.
5. Pull the red tape backing away about an inch, set the dam snugly against the shower wall and floor, and pull the backing away slowly as you work down the length.
6. Press firmly along the entire dam, then clean the surfaces again and run painter's tape down both sides.
7. Apply a thin bead of silicone along the lower edge on both sides and on both end caps, and smooth it so every gap is sealed.

Two rules protect the result. On a tile floor the grout line beneath the dam must be caulked so water cannot travel under it, and the base threshold must never be drilled, because drilling the threshold voids the base warranty. The self-adhesive design means no fastener has to go through the base.

Ordering a Barrier-Free Base, Including the 32 by 60 with a Right-Hand Drain

Ella's wheelchair accessible roll-in base comes in three standard sizes, 30 by 60, 32 by 60 and 36 by 60 inches, all ADA curb-less pans, and the drain position is specified when you order. The 32 by 60 inch barrier-free base is offered in left and right configurations and is ready to ship, so a right-hand drain in that size is a standard choice rather than a special request. Tell your Ella dealer or the team at (800) 480-6850 where your existing drain line sits in the floor and they confirm which drain position matches. When a standard size will not fit, custom rectangular bases go up to 44 inches wide by 80 inches long with the drain placed left, right or center, at least 9 inches from each wall. What is a roll-in shower and who should get one? lists the sizes and the caregiver options.

Shower products are sold per item rather than as one bundle, so a complete roll-in shower is assembled from the base in your size and drain position, a wall system sized to it, the dam that ships with the base, and the extras you want: a weighted anti-bacterial nylon curtain, a stainless curtain rod, a slide bar with hand shower, and a seat if needed, with folding benches and seats rated from 300 to 600 pounds or a 36 by 60 base with a molded seat. Wherever you live, your Ella dealer or the team confirms the size, the drain side and current stock for your order. If the project must meet an accessibility code, ADA standards generally limit the threshold in a roll-in compartment to 1/2 inch, and state and local codes decide what passes inspection, so confirm the standard with your local building department. What is a roll-in shower and who is it designed for? covers the code side in more depth.

Watch: The Ella Shower Dam, Keep Water In, Roll In With Ease | Ella's Bubbles with chapters and a full transcript.

Related Guides

• Installing Ella Shower Bases, the Flexible Shower Dam, and Shower Walls
• Custom-Size Shower Bases: Size Ranges, Threshold Options, Drain Placement Rules, Construction, and How to Request One
• Shower Base Sizes and Thresholds Compared: AcrylX Barrier-Free, SMC Linear-Drain, Molded-Seat and Cultured Marble Bases

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