A small bathroom layout is set by the soil stack, the door and the window. The WC goes where its waste can reach the stack directly; the shower goes where its drain has enough depth; the basin is the most flexible piece. Doors that open outward or slide, a shower across the full width and a wall-hung WC are the most effective changes. Electrical positions must respect the zones that Spain’s low-voltage regulation sets around the shower.
What are the fixed points in a bathroom?
The soil stack is the vertical pipe that carries waste down through the building. In an apartment block it is a shared element and cannot be moved by one owner. The WC must connect to it with a short, steep pipe, so the WC usually stays close to it.
The door position is set by the corridor and the partition walls. It can sometimes be moved or changed to a sliding door, but that has knock-on effects in the next room.
The window, if there is one, is part of the façade and cannot be moved. It affects where the shower sits, because a window inside a shower area is hard to keep dry and private.
Everything else is negotiable within the limits of these three.
Which layouts work in narrow rooms?
- Everything on one wall. Basin, WC and shower in a line along the longest wall, with the door on the opposite side. Simple plumbing, easy circulation.
- Shower at the end. The shower occupies the full width of the far end of the room, with basin and WC along the side walls nearer the door. Suits rooms that are long and narrow.
- Facing walls. Basin on one side, WC on the other, shower at the end. Works where the room is slightly wider and the stack is close to one corner.
Our small bathroom renovation page shows how these choices translate into the finished room.
How much space does each fitting need?
Rather than quoting fixed dimensions, which vary by product, think in terms of use. In front of the WC you need room to stand and sit without knees touching the opposite wall. Beside it, enough space that elbows do not hit a wall or the basin. In front of the basin, room to lean forward. Inside the shower, enough length that the spray stays within the screen and enough width to turn round comfortably.
We set the room out to scale with the actual products you have chosen or are considering, because a compact WC and a standard one can differ noticeably in projection.
Should the door open in or out?
An inward-opening door sweeps an arc inside the bathroom where nothing else can go. In a small room that arc often clashes with the basin or WC. Opening outward frees that space but needs room in the corridor; a sliding door, either surface-mounted or running into a pocket in the wall, frees it entirely. A pocket door requires a suitable partition, which may mean rebuilding part of the wall in plasterboard.
Outward-opening doors also have a safety advantage: if someone falls against the door inside, it can still be opened from the corridor.
Where can lights and sockets go?
Spain’s low-voltage electrical regulation, the REBT, sets out specific rules for rooms with a bath or shower in its technical instruction ITC-BT-27. It defines zones around the bath or shower: zone 0 is inside the tray or bath, zone 1 rises above it to a defined height, zone 2 extends a set distance beyond zone 1, and zone 3 extends further still. Sockets and switches are generally not allowed in zones 0 to 2, apart from specific exceptions such as shaver supply units in zone 2; in zone 3 sockets are permitted with protection such as a residual-current device of no more than 30 mA.
In a small bathroom these zones cover much of the room, so the position of the shower determines where the mirror light, the shaver socket and the extractor switch can go. Our authorised partner installers apply these rules when fixing positions.
What about ventilation in an inside bathroom?
Many small bathrooms in apartments have no window, only a grille into a shared shaft. For new dwellings, the CTE’s HS 3 section on indoor air quality expects extraction openings in bathrooms and air flowing from the dry rooms to the wet ones. In a renovation of an existing apartment, how far these requirements apply depends on the scope of the work (to be verified case by case), but good extraction is worth having regardless.
An extractor fan on its own switch, or linked to the light with a run-on timer, makes a small room far more comfortable. See the guide on damp and mould.
What storage works in a small bathroom?
Niches recessed into a stud wall or a solid wall take bottles out of the shower and off the basin. A counter that runs the full width above a wall-hung WC gives a shelf without taking floor space. A mirror cabinet recessed into the wall adds storage without projecting. Open shelves near the shower collect water and look cluttered quickly in a small room.
How do you test a layout before building it?
We draw the room to scale with the chosen fittings and mark the door swing, the shower spray area and the electrical zones. Sometimes it helps to mark the outlines on the floor of the stripped room with tape before the walls are closed. It is the cheapest moment to change your mind.
When the layout is fixed, the job follows the sequence described on our bathroom renovation page. For ideas that work in practice, see best ideas for a small bathroom.
Official sources
- REBT, Real Decreto 842/2002 (ITC-BT-27, rooms with a bath or shower) – BOE consolidated text
- Código Técnico de la Edificación, DB HS Salubridad (HS 3 indoor air quality)
Bauman Raymond Attila · Reforma Baños Málaga · Avenida Antonio Belón 3, Marbella. Last reviewed: 05/11/2026.
