Can you have a curbless shower in an old building on a high floor?
You can, but not everywhere and not always the same way. A walk-in shower flush with the floor needs 8 to 10 cm of floor depth above the structure for an ordinary drain, or about 6 cm with a low-profile one. If the old floor structure cannot be lowered, the floor is raised or the drain goes into the wall.
Flats in the Eixample or Gràcia are generally in buildings whose floors are timber or steel beams with a brick vault (revoltón, Catalan vault). That vault cannot be cut open for a drain: it carries load. So the first step in the design is to find out what is under the floor, and only then decide which shower is possible.
The floor is opened in one or two places and an engineer calculates. Only then can you talk about details, the drain and the height.
What does a curbless shower need technically?
Four things: a fall in the floor toward the drain, a drain with a trap, continuous waterproofing, and a floor depth in which it all fits.
The fall is 1 to 2% (the floor drops 1 to 2 cm per metre of length). For 1.2 m from wall to drain, that is a drop of 1.2 to 2.4 cm. The screed varies in thickness and is laid with laser control: an error of 3 mm ends up as a puddle.
Waterproofing goes down as a continuous layer: a sheet or liquid membrane runs up the walls in the shower zone to the ceiling and 15 to 20 cm elsewhere, and seals to the drain flange. After it is laid a test is done: the zone is flooded for 24 to 48 hours and the floor below is checked. Only then are tiles laid.
Linear drain or point drain?
A linear drain suits large-format tile; a point drain is cheaper and simpler but needs a fall in four directions. If the design has large slabs, choose linear.
With a linear drain the floor has a single fall and tiles are cut as little as possible. It sits by the wall or at the entrance. A linear drain typically handles 0.5 to 0.8 l/s, and a rain shower delivers 15 to 25 l/min (0.25 to 0.4 l/s), so there is margin, though you choose from the data sheet.
A point drain in the centre makes a pyramid with four falls: tile is cut into triangles and large formats do not work. Mosaic or tiles up to 30 by 30 cm suit better. In return, the floor depth needed is less than with a linear drain, which sometimes decides it.
What to do if the floor structure cannot be lowered
There are four solutions, and they combine. First: raise the whole bathroom floor by 6 to 10 cm with a ramp at the entrance. Second: build a platform only under the shower with one step. Third: use a low-profile drain about 6 cm tall or a wall outlet, which needs no depth. Fourth: prefabricated boards with a built-in fall, laid on the floor structure in a layer a few centimetres thick.
Each option has a cost: a platform and a raised floor mean a threshold at the door, so the entrance is no longer fully barrier-free. For accessibility or for older owners that matters, and we treat it separately in our article on the accessible bathroom.
The weight of the screed also matters: a 6 cm cement screed adds load to an old floor. If the structural engineer insists, it is replaced with lightweight boards and dry mixes.
Why does water get out of the shower?
Five causes: a wrong or too small fall, a drain of insufficient capacity, no screen, the wrong spray direction, and an outside floor higher than the zone itself.
A fall of less than 1% drains badly, and an error in the opposite direction makes a puddle by the wall. The glass is made long enough: a fixed panel of 90 to 120 cm covers the main direction of the spray. The rain head and handset are aimed at the wall or the glass, not at the entrance.
A second defence: a small concealed threshold (5 to 10 mm) or a channel drain by the door goes in front of the entrance, which do not hinder a step but stop the water. The floor outside the zone must be lower or fall back toward the shower. These details are settled before tiling.
What are the drawbacks of a curbless shower?
The first is price: waterproofing, laser levelling of the fall and the drain cost more than a tray. The second is space: a flush shower needs at least 90 by 120 cm, and preferably more, or water reaches the rest of the floor.
The third is slipperiness. Shower tile is wet and is chosen for high slip resistance. The CTE (DB SUA 1) requires class 3 for showers (the highest, Rd above 45), but in public and commercial buildings; in a private flat the rule is not mandatory. Class 3 is taken as a benchmark and you ask the supplier for the tile's data sheet.
The fourth is cold: the floor has no curb and no protection from draughts, so underfloor heating in the shower is almost a must. The fifth is maintenance: the drain and flange are cleaned, and the drain must have a removable grate and access to the trap.
How to design it, and what BCN YARD does
Start with an opening-up and a survey: floor depth, floor structure type, position of the stack, distance to the drain. Then choose the variant: fully flush, with a ramp, with a platform, or with a wall outlet.
Then the plan, in order: plumbing routes, drain, fall, waterproofing, water test, tiling and glass. A mistake at an early stage can only be corrected by lifting the tile. More on bathroom works in the full bathroom renovation guide.
BCN YARD checks the floor structure before the design, runs the watertightness test before tiling and picks the shower variant for your flat. If you are planning a curbless shower in an old building, we visit, see what is under the floor and tell you which option suits you.
Frequently asked questions
Can you have a curbless shower in a high-floor flat in an old building?
Yes, once you know what is under the floor. A normal drain needs 8 to 10 cm of depth, a low-profile one about 6 cm. A vault or beam floor is not cut open, so the bathroom floor is raised 6 to 10 cm with a ramp, a platform is built under the shower, or the drain goes into the wall. The structural engineer decides after an inspection.
Linear drain or point drain?
Linear is better for large tile: one fall and almost no cuts. Point is cheaper but gives falls in four directions, tile is cut into triangles, and it suits mosaic or pieces up to 30 by 30 cm. A point drain needs less floor depth, which sometimes decides.
Why does water get out of the shower?
Most often a small or wrong fall, a weak drain or a short screen. The fall is 1 to 2%, a fixed glass panel of 90 to 120 cm covers the main spray direction, and a low concealed threshold or a channel drain goes at the entrance. The outside floor must be lower than the zone or fall toward the shower.
What are the drawbacks of a curbless shower?
It costs more than a tray because of waterproofing, laser falls and the drain. It needs at least 90 by 120 cm. Tile for showers is chosen at slip-resistance class 3. Without a curb it feels colder, so underfloor heating helps. The drain needs maintenance: a removable grate and access to the trap.