Planning a curbless shower

A curbless shower removes the threshold between the shower and the rest of the room. The floor simply continues. It makes small bathrooms read as larger, it is far easier to clean, and it removes the one thing in a bathroom most likely to cause a fall.

It is also the detail most often quoted optimistically and delivered badly.

The geometry problem

Water has to fall towards the drain, and the drain has to sit below the finished floor. In a shower with a curb, that vertical space is created by the curb itself. Remove the curb and the space has to come from somewhere else.

1. Recess the floor structure, which means cutting or resizing joists and is only possible in some assemblies.
2. Build the surrounding floor up, which raises the whole room and affects door heights and thresholds.
3. Use a low-profile linear drain assembly, which reduces but does not eliminate the depth required.

Which of those is available depends entirely on your floor. It is the first thing we check on site, and it is the reason we will not quote a curbless shower from photographs.

One slope, not four

A traditional centre drain requires the floor to fall towards a point from four directions. That is fine with mosaic, which can follow a compound slope, and awkward with anything larger.

A linear drain against one wall lets the entire floor fall in a single direction. This is what makes large-format tile possible in a shower floor, and it is usually the right answer for a curbless build.

Keeping water in the wet zone

Without a curb, containment comes from three things: enough slope, enough distance between the shower head and the open edge, and a waterproofing plane that extends well beyond the visibly wet area.

In practice we extend the membrane across the whole bathroom floor in a curbless build. It costs comparatively little at that stage and removes the failure mode entirely.

Decide early

Curbless is a structural decision, not a finishing decision. Raised at the design stage it is often straightforward. Raised after demolition it may still be possible. Raised after the floor is levelled it usually is not, without going backwards.