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Cross-market term

Wet room and curbless shower

A bathroom in which the floor is tanked and falls to a drain, so the shower has no tray and no upstand and the whole floor is designed to be wetted.
  • 4Markets
  • NoSame thing everywhere
  • 3Calculators

What it is called, by market

One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.

  • United Kingdom

    Same word, different thing

    wet room

    also wetroom, level access shower, tanked floor, walk-in shower

    Names the ROOM, and the defining feature is that the floor is the tray. A WALK-IN shower may still have a low tray, so the two are commonly conflated and are different specifications.

  • Australia

    Same word, different thing

    wet area

    also wet room, hobless shower, waterproofed area

    WET AREA is a regulatory classification covering any area requiring waterproofing — a whole bathroom, a laundry — rather than the level-floor shower arrangement specifically.

  • United Statesyours

    Same word, different thing

    curbless shower

    also barrier-free shower, zero-threshold shower, wet room

    CURBLESS names the shower, not the room. And American wet room has a second meaning — a shower and tub inside one glazed enclosure — which is a layout rather than a waterproofing strategy.

  • Canada

    Close, not identical

    curbless shower

    also barrier-free shower, roll-in shower

    As the United States, with roll-in used where wheelchair access is the driver and the dimensions are set by accessibility rules.

The governing standard, by market

  • United Kingdom

    BS 5385-4 / Approved Document M

    Design and installation of ceramic tiling in specific conditions including wet environments, and accessible bathrooms.

  • United States

    ANSI A118.10 / TCNA Handbook

    Load-bearing bonded waterproof membranes, and tile installation methods including curbless shower assemblies.

Calculators for this

Each works in either measurement system, and the terminology on the page follows whichever market you have selected.

Below-Grade Waterproofing Membrane Roll Calculator →Floor Drain Slope Screed Volume Calculator →Floor Crack Isolation Membrane Coverage Calculator →

Frequently asked questions

What makes a wet room different from a bathroom with a big shower?
The floor is the tray, and that changes the construction rather than the fittings. A conventional bathroom relies on a shower tray or an enclosure to contain the water, so the floor outside it only has to survive splashes. In a wet room there is no containment: water reaches the whole floor, so the whole floor has to be tanked with a continuous waterproof membrane, dressed up the walls to a height, sealed at every penetration, and laid to falls toward a drain. The failure mode is correspondingly different too — a leaking shower tray shows itself at the tray, while a wet room failure delivers water into the structure under the entire room and often appears on a ceiling below, a long way from the shower.
Why are the falls harder than they look?
Because the floor has to slope in two dimensions toward one point while remaining level enough to stand a piece of furniture on and to meet the doorway flush. That means a shallow fall — typically a small percentage — formed either by a proprietary pre-formed tray sunk into the floor, or by laying the screed to a shaped fall around the drain, and it has to be accurate: too little and water stands or travels the wrong way, too much and the floor is uncomfortable and tiles are hard to lay. On a timber floor it is harder again, because forming the fall usually means cutting into or building up on the joists, and the drain needs depth below the floor for its trap and its fall to the waste — which is often the constraint that decides whether a wet room is possible at all on an upper storey.
Where do they actually fail?
At the junctions and the penetrations, almost never in the middle of the membrane. The recurring list is short and consistent: the joint between floor and wall, where the membrane has to turn a corner and is most likely to be stretched or unbonded; around the drain body, where the membrane has to be clamped rather than merely stuck; at the doorway, where the tanking has to stop and the falls have to hold water back without a threshold; and at every pipe, fixing and screw that passes through. The second family is movement — a timber floor that deflects under a person's weight will crack a rigid membrane and its tiles, which is why a wet room over joists usually calls for a decoupling layer and a stiffer floor than the room had.