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Walk in shower: an architect's guide to sizes, drains and waterproofing
Walk in shower: sizes, falls, drains and waterproofing, explained by architects for a villa bathroom.
Walk in shower: what it is and when it makes sense
A walk in shower is one you enter without a door and often without a step: a fixed glass panel, a continuous floor, water running towards the drain. In a villa it is far more than a fitting. It changes how the bathroom feels, because the floor carries on and the space is not interrupted. That is exactly why it is one of the hardest details to build well.
Most guides talk about models and glass prices. We talk about what you cannot see: levels, falls, drainage, waterproofing. A good walk in shower is a small work of architecture, and almost every problem starts in the design, not in the installation.
Walk in shower: the essentials
- A zero threshold is a result: levels, falls, drain and waterproofing are designed together.
- The typical fall is 1.5–2%: over 1.20 metres that means 18–24 millimetres.
- Below the surface you need depth: about 120 millimetres in one technical example.
- The membrane does not create the fall: it goes on a surface already sloped.
- The real test is with every outlet running, before you accept the work.
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Walk in shower sizes and proportions
There is no single compulsory size. Commercial sheets quote different values, and in a villa bathroom the reference is a body in motion: arms open, a step back from the water, room for a towel out of the spray. An open shower works when the water does not reach where it should not. The shorter the glass, the more depth or the better aimed the spray you need.
As architects we reason like this: the rain head goes far from the opening, the controls can be reached without entering the spray, the niche sits on the least wet wall, the glass drops to the floor or nearly. The opening goes where the spray does not reach, even if another spot looks more elegant on plan. In a wide bathroom, a shower running between two walls with glass on one side feels like a room of water.
Walk in shower design: which system to choose
There are three construction methods, as summarised in a technical guide by Edilizia.com, September 2026 (in Italian):
| System | When to choose it | Key check | Limit |
|---|---|---|---|
| Prefabricated tray | Certain timing, little depth available | Drain level, perimeter joint | Less flexible sizes and cuts |
| Sloped board | Finish continuous with the floor | Compatibility with drain, membranes and adhesives | Sizes tied to the system |
| Site-laid screed | Custom shapes, large areas | Real falls, curing, connection | Depends heavily on the installer |
In a new villa, with a floor slab planned in time, a screed or board allows complete continuity with the floor. In a renovation the winner is often the system that needs least depth. You do not choose from a catalogue: you choose after measuring how much space there is below the finished floor.
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Falls and levels: the heart of the design
The fall is the distance from the drain multiplied by the percentage. Typical values are about 1.5–2% but not universal: the design, the drain and the manufacturer’s instructions decide. One system maker quotes a range between 1 and 2.5% (in Italian). In millimetres, it means this:
| Distance from drain | Drop at 1.5% | Drop at 2% |
|---|---|---|
| 0.80 m | 12 mm | 16 mm |
| 1.00 m | 15 mm | 20 mm |
| 1.20 m | 18 mm | 24 mm |
| 1.50 m | 22.5 mm | 30 mm |
Below the finished surface you must fit the trap, pipe, sloped base, membrane, adhesive and finish. In the same guide’s example: 80 millimetres for the trap, 15 lost in the connection, 25 for base and finish, for about 120 millimetres in total. In a renovation, survey the direction and depth of the existing pipe before ordering a tray, and never cut into a slab without a structural check.
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Point drain or linear channel
A point drain usually creates four falls and needs cuts, often visible on large formats. A linear channel allows a single plane sloping towards one wall: it is the cleanest choice with large slabs, but it concentrates the joint between wall, floor and drain. Check the flow too: an 18-litre-per-minute head and a 10-litre hand shower make 28 litres per minute, about 0.47 litres per second, and the drain must handle that with a margin for grate and dirt.
Be careful with low-profile traps, useful when depth is short. The European standard EN 1253-1 calls for a water seal of at least 50 millimetres; products with a lower seal fall under specific conditions and need checks on use and venting, or odours follow.
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Waterproofing: where the damage begins
Grout does not waterproof and silicone is not a solution: the seal lies under the finish. The membrane does not create the fall and must be laid on a surface already sloped; if the fall comes only from adhesive or tile, any water that gets through sits on the membrane. The drain body needs a flange or collar to connect it. Corners, valve penetrations and niches need preformed pieces or elastic collars.
The references cited by the technical guide are EN 14891 for liquid waterproofing and UNI 11493-1:2025 for tiling in Italy. Two tests must come before closing the site: a watertightness test after the system’s curing time, and a flow test with the grate fitted and every outlet running. A bathroom rebuilt because of a leak costs far more than the shower.
Materials: stone, porcelain, resin
A shower floor must drain and must not be slippery. Safety is measured: ask for the test method and result for the exact finish (EN 16165), not the product name. Honed stone is beautiful but must be chosen with care and needs upkeep, as we explain in our natural stone guide. Large slabs cut down joints but complicate falls. Mosaic follows slopes naturally. Resin gives continuity and asks for an expert applicator.
Glass is an architectural choice: low-iron glass disappears, smoked or fluted glass draws the space. Choose profiles and fixings with the same care. Be honest about upkeep: a fixed panel needs a squeegee after every use, especially with hard water. If your water is hard, plan treatment for the whole house, not just the shower.
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Light, air and fittings: designing the shower
Light in a shower should be designed as in a room. A raking blade along the wall brings out the stone, but it also shows every flaw in the installation: if the finish is not perfect, a softer light from above is better. In a deep shower a lit niche draws the eye to the back and lengthens the space. Fittings must have the protection rating for wet zones, and the systems designer says where they can go.
Air is the other half of comfort. An open shower lets more steam into the bathroom, and without air change the damp ends up on mirrors, ceilings and furniture. In a well-insulated house, mechanical ventilation solves this quietly, provided the vents are designed with the ceiling. In an existing house, plan at least adequate extraction and a window that really opens.
Fittings decide daily use. A thermostatic mixer gives a stable temperature, and the control should sit outside the spray so you can set the water before stepping in. A ceiling head and a hand shower on two ways are the most practical pair: the head is the pleasure, the hand shower cleans the shower. Concealed parts are chosen before the finish and must stay accessible: a valve replaceable through a hidden hatch saves breaking a stone wall ten years on.
The wet room: when the shower becomes architecture
In some villas the master bathroom stops being a sum of fittings and becomes a single room, with floor and walls in one material, where shower and bath share the same wet zone. It is a fascinating solution because it frees the rest of the bathroom from water, and it asks for even stricter design: the whole room is waterproofed and sloped, and the glass separates the wet zone from the dry side with its furniture and wardrobes.
The link with the outdoors is another theme. A shower facing a private patio or walled garden is one of the great pleasures of a house, provided you design the view, the privacy and the shelter from wind. The route counts too: from bedroom to shower, from pool to shower, from garage to utility bathroom. In a villa, the passing shower near the pool or gym is often the most used and deserves the same care.
Walk in shower pros and cons
Pros: a continuous floor, step-free access where the space allows, visual calm, more light in the bathroom. Cons: with no door, air moves in winter and the room can feel colder; spray must be controlled; the work is more delicate than a traditional tray. Heating matters: a warm wall or floor changes the experience, as our guide to underfloor heating explains.
On accessibility, having no threshold is not enough: manoeuvring space, a seat, grab points and reachable controls all count. If the house is to accompany you for many years, think about it now: reinforcements for grab rails you may never fit can go in the wall today.
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How much does a walk in shower cost?
The orders of magnitude given by Edilizia.com for 2026 refer to the technical part, in Italy:
| Item | Order of magnitude, Italy 2026 |
|---|---|
| Prefabricated tray or tileable board | about €250–900 |
| Point drain or linear channel | about €100 to over €600 |
| Complete installation in a prepared bathroom | about €1,500–3,500 |
| With stack moved, demolition or large slabs | over €4,000 |
In a villa these figures are the minimum: custom glass, stone, concealed fittings and systems can multiply them. Our advice is to spend first on the hidden part, because you cannot redo it without demolition.
The brands in our catalogue
The Villa Edit catalogue gathers the companies we consider the best and that the studio looks at for its projects. For the bathroom, Gessi for taps and Antonio Lupi for furniture are brands the studio has used. The catalogue also holds Agape, Ceramica Cielo, Fantini, Treemme and Colombo; for shower enclosures Vismaravetro, and for trays Milldue. They are not partners or sponsors of this guide: the choice depends on each project. The full picture is in The Villa Edit.
Walk in shower: nine mistakes to avoid
- Creating the fall with adhesive alone.
- Cutting the membrane flush with the grate and closing it with silicone.
- Cutting into the slab without a check.
- Testing watertightness before curing.
- Accepting the work without a test using the real head.
- Aiming the spray at the opening.
- Choosing stone from a photograph, without a slip test.
- Forgetting bathroom ventilation and heating.
- Ordering the tray before surveying the existing drains.
Walk in shower: frequently asked questions
What is a walk in shower?
It is an open shower you enter without a door and often without a step, defined by a fixed glass panel.
What are the disadvantages of a walk in shower?
It can feel colder in winter, spray must be controlled, and the build is delicate: falls, drain and waterproofing must be designed together.
What fall does a level shower need?
Typical values are about 1.5–2%, but the design, drain and manufacturer’s instructions decide. At 2%, over one metre, that is 20 millimetres.
Can you add a walk in shower in a renovation?
Often yes, but measure the depth below the floor: trap, pipe and layers can need about 120 millimetres. If it is not there, consider low-profile systems or a slim tray.
How do you clean a walk in shower?
Use a squeegee on the glass after each use and cleaners suited to the finish. Clean grate and trap regularly, especially with hard water.
How much does a walk in shower cost?
For the technical part in a prepared bathroom, orders of magnitude for Italy in 2026 are about €1,500–3,500, over €4,000 with demolition or large slabs. Finishes and glass in a villa can multiply this.
Point drain or linear channel?
A channel gives a single plane, suited to large slabs. A point drain needs four falls. The finish format and joints decide.
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Sources: Edilizia.com, 2 September 2026; wedi press release, 2023. Checked on 31 October 2026: these are good practice, and the standards cited must be read in the text in force. Photos: projects by Federico Cappellina Architects; the images show studio bathrooms and do not illustrate a specific system or brand cited.
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