How do you prevent leaking from a curbless shower?

[Veronica]

I want a curbless shower stall for easy access. The contractor says that it involves digging into the concrete and then layering it with some "mud" to position the drain.

How do you prevent leaking from a curbless shower?

[home improvement guy]

Curbless showers, sometimes called zero-threshold, add contemporary style to bathrooms and provide an accessible option for those aging in place. However, without the proper slope, these showers will not drain correctly and could lead to moisture issues later.

PROPER DRAINAGE CRITICAL FOR A CURBLESS SHOWER PAN

To create the correct slope, the Tile Council of North America handbook says installing curbless showers requires a "depressed slab." Building this involves cutting out the entire shower floor area in order to pour a shower pan that slopes toward the drain. A curbless shower pan should slope one-quarter inch for every foot of shower.

Installing a curbless shower on a slab is more complicated than on a floor with wood framing. With concrete slabs, cutting into the floor and moving plumbing are more complicated and labor-intensive. Because of this, installing a curbless shower on a concrete slab is typically more expensive than on a floor built with wood joists.

Some showers may require a second drain just outside the shower to ensure splashed water doesn't sit on the tile flooring.

CREATING A ZERO-THRESHOLD SHOWER WITHOUT CUTTING

Some companies avoid cutting into the concrete by building up the bathroom floor everywhere but the shower. This allows them to create the proper slope for the shower. But it also makes a ledge in the bathroom's doorway, which could cause stubbed toes or tripping.

Either way, the high point of the floor must be located outside the shower. "The location of the high point of the floor is especially critical when a secondary drain is not included outside the shower area," the TCNA handbook says.

WATERPROOFING CURBLESS SHOWERS

Floors and walls should be waterproof inside the curbless shower and at least one foot beyond it. This requires more than cement backer board on the walls or flooring. Installers should apply a vapor-proof membrane over the backer boards before setting a single tile.

Homeowners may desire a shower without a glass door, but to protect the rest of the bathroom from excessive moisture, a door may be necessary. Otherwise a much larger portion of the bathroom will require waterproofing, some installers say.

HOW MUCH SHOULD A CURBLESS SHOWER COST?

A typical walk-in shower with a curb and door costs about $2,500 to $5,000 on average. Installers say the special modifications for a curbless shower add another $500 to $700 or more depending on the tile type and shower size. For homeowners looking to make their bathrooms more accessible, the cost may prove well worth it.