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

A shower dam is a flexible, collapsible rubber strip fixed across the open entry of a curb-less shower base so the stall holds water without a raised curb. You need one when the shower is a roll-in shower, because a wheelchair, walker or shower chair has to roll straight in with nothing to cross, and the dam flattens under the wheels and springs back once they pass. Ella ships the dam as standard equipment with its roll-in barrier-free bases, which are described in What is a roll-in shower for wheelchair users?.

What a Shower Dam Is

Ella's dam goes by several names: collapsible rubber dam, water retainer, flexible shower dam and collapsible threshold. They all describe the same part, a self-adhesive rubber strip that sits across the entry of the base in the spot where a curb would normally be. The material is compressible and waterproof, and it is made for exclusive use with the barrier-free wheelchair accessible shower base. When a wheel rolls over it the strip flattens, and once the wheel passes it returns to its original shape and holds the water in the stall. That is the whole idea: the water control of a curb without the curb.

The video on this page shows the dam compressing under a caster and springing back, then walks through the installation and finishes by showing how well the dam contains water in the stall. The dam attaches with strong, water-resistant self-adhesive tape, so no drilling is involved. That matters for the warranty as well as for the water, because the base threshold must never be drilled. Drilling the threshold voids the base warranty.

When You Need a Shower Dam

The dam belongs on a curb-less base. Ella's standard roll-in bases are ADA curb-less pans in 30 by 60, 32 by 60 and 36 by 60 inch sizes, with the drain position specified when you order, and custom rectangular bases can be made up to 44 inches wide by 80 inches long. The entry on these bases is the lowest Ella makes. AcrylX barrier-free bases have a beveled roll-in entry of 3/4 inch to 1 1/8 inch depending on size, and SMC bases are 1 inch or 1 1/8 inch. With so little edge at the entry, something else has to keep water inside, and that job goes to the dam. You need one when:

• The person bathing stays seated in a wheelchair or shower chair and rolls straight into the stall. The dam is made for wheels to roll over while entering and exiting.
• The person uses a walker. The dam flattens under a walker just as it does under a wheelchair, and the flush entry removes the lip a walker or a foot can catch on.
• A caregiver assists with bathing. The open entry leaves room to help, and grab bars and a shower door can be added to the base.
• The project must meet an accessibility standard. ADA standards generally limit the threshold in a roll-in shower compartment to a maximum of 1/2 inch, which is why the barrier-free line is the one an architect, facility or inspector looks at. Confirm the standard that applies with your local building department, since state and local codes decide what passes inspection.

Who the roll-in layout suits, and who is better served by another base, is covered in What is a roll-in shower and who is it designed for?.

When You Do Not Need One

Any base with a raised edge already keeps water in, so a dam is not part of the package. Ella offers several of these for people who do not need a flat approach:

• The 3 inch step-in threshold base, for anyone who prefers a slightly raised edge.
• One-piece and three-piece shower stalls, which have a 4 inch threshold.
• The SMC 1 inch low-profile reversible base, whose 1 inch profile is a low threshold you step over rather than roll over.
• The low-threshold acrylic and cultured marble bases, which have a molded threshold instead of a dam.

A walk-in tub does not use a dam either, because its sealed door holds the water and you shower from the seat with the hand shower. If you are weighing a tub against a curb-less shower, Should I choose a walk-in tub or a roll-in shower? lays out the trade-off. In short, choose the roll-in shower and its dam when the bather stays in a wheelchair or shower chair, and choose the tub when the goal is to sit and soak.

How the Dam Is Installed

The installation shown in the video is a careful adhesive job rather than a plumbing job, and the one step that cannot be skipped is cleaning. The adhesive will not bond to a surface that has not been wiped down with alcohol first.

1. Measure precisely, then clean all surfaces thoroughly with alcohol.
2. Lay a line of tape on the surface as a guide, measure how much dam material is needed, mark it and cut carefully.
3. Insert the plastic end caps and apply silicone to any gaps around them.
4. Peel the red tape backing away about an inch, set the dam down snugly against the shower wall and floor, and pull the backing away slowly as you work down the length of the dam.
5. Press firmly along the entire length so the adhesive seats.
6. Clean the surfaces again, lay painter's tape on both sides of the dam, and run a thin bead of silicone along the lower edge on both sides, smoothing it into the gaps. Silicone both end caps as well.

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 voids the base warranty. The full picture of how the base, the walls and the dam work together is in What is a roll-in shower and how does it work?.

Ordering a Base with a Dam

Ella sells shower products per item rather than as one bundle, so a roll-in shower is put together from the base in your size and drain position, a wall system sized to it, and any accessories you want. The dam itself comes standard with the roll-in barrier-free bases, so it is not a separate line on the order. The 32 by 60 inch barrier-free base is offered in left and right configurations and is ready to ship, and each of the three standard sizes is available with a left or right drain. Tell your Ella dealer or the team at (800) 480-6850 where your existing drain line sits in the floor, and they will confirm which drain position matches your size. Once the base is set, the wheelchair or walker rolls in over the dam, the water stays in the stall, and there is no curb to lift over on the way out.

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

Related Guides

• What is a roll-in shower and who should get one?
• Installing Ella Shower Bases, the Flexible Shower Dam, and Shower Walls
• What Is a Collapsible Rubber Dam on a Roll-In Shower?

Common Questions