Knowing how to design a bathroom comes down to one discipline most people skip: settle the layout before you fall for the fittings. In a London home the plumbing, the roomâs size and the natural light decide far more than any tile sample, so the order you make decisions in matters. This guide walks through planning the layout, choosing the suite, getting storage and lighting right, and the finishes that make a compact bathroom feel calm rather than cramped.
It sits alongside our other room-by-room guides, including how to design a kitchen, and the practical interior design cost guide for London.
Start with the plumbing, not the look
The most expensive thing in a bathroom is moving water. The soil pipe that serves the toilet and the supply and waste runs largely fix where the toilet, basin and bath or shower can sit, and relocating them means lifting floors and rerouting pipework. So map what cannot easily move first, then design around it. If your heart is set on a different layout, price the plumbing changes early, because that one decision drives much of the budget.
Plan the layout and the clearances
Sketch the room to scale and place each fixture with the space it needs to be used comfortably: room to stand at the basin, to sit at the toilet, and to step in and out of the shower without clashing with the door. Keep a clear path through the room and make sure the door swing does not foul a fixture. In tight London bathrooms, lining fixtures along one or two walls keeps the plumbing simple and the floor open, which both costs less and feels bigger.
Bath or shower: decide honestly. If no one bathes, a walk-in shower usually frees the most usable space and feels more generous. Keep a bath if you have young children or it matters for resale, and consider a shower over the bath as a compromise. Wall-hung fittings show more floor and read as lighter in a small room.
Storage that earns its place
Bathrooms fail on clutter more than anything else. Build in storage from the start: a vanity unit under the basin hides pipework and holds everyday things, a mirrored cabinet adds concealed storage without taking floor space, and a recessed niche in the shower wall keeps bottles off the floor. In a period London property with a chimney breast, the alcoves either side are ideal for slim shelving or a tall cupboard.
Lighting and ventilation
Bathrooms need layered light and proper airflow, and both are easy to underspecify. Combine bright, even ceiling light for the whole room with task light around the mirror so you are not lit from above alone, and use fittings rated for the damp zones they sit in. Ventilation is not optional: fit an extractor sized for the room, ideally on a humidity sensor, and keep a window or trickle vent where you can. Good airflow is what stops the damp and mould that wreck finishes.
Tiles, surfaces and colour
Finishes set the mood once the practical work is done. Large-format tiles mean fewer grout lines, which makes a small room calmer and easier to clean, while a single tile carried across walls and floor blurs the boundaries and feels larger. Keep the palette mostly quiet and add character through one material, a textured tile, a stone basin or warm brass taps, rather than several competing features. Make sure wet areas are tanked and waterproofed correctly before any tiling goes on.
Heating and the finishing touches
A heated towel rail is the standard bathroom heat source and doubles as somewhere to warm towels, and underfloor heating is a worthwhile upgrade in a room you stand in barefoot. Plan the small things too: a demister pad behind the mirror, the right sealant lines, and somewhere to hang and store towels. These details are what separate a bathroom that merely looks finished from one that works every day.
Common mistakes to avoid
- Choosing fittings before fixing the layout: the layout should lead, always.
- Underpowered ventilation: too small a fan guarantees damp and mould.
- Forgetting storage: plan it in, do not bolt it on later.
- Poor lighting around the mirror: overhead-only light casts unflattering shadows.
- Skimping on waterproofing: the one place never to cut corners.
- Too many feature finishes: let one material do the talking.
- Ignoring the door swing: a door that hits a fixture spoils the whole room.
Bring it together
Design a bathroom in the right order, plumbing and layout first, then storage, lighting and ventilation, then finishes, and the result feels considered and lasts. If you would like the layout and specification handled for you, see what we do on the Vertigo Interiors homepage and our cost guide.
Frequently asked questions
How do you design a bathroom layout?
Start from the fixed points: the soil pipe and water supply largely dictate where the toilet, basin and bath or shower can sit, since moving them is the most expensive change. Map the door swing and the space each fixture needs, keep a clear path between them, and only then choose finishes. In a small London bathroom, a walk-in shower in place of a bath often frees the most usable space.
What is the best layout for a small bathroom?
Line the fixtures along one or two walls to keep the plumbing tight and the floor clear, swap a bath for a walk-in shower if you do not need to bathe, and use a wall-hung toilet and basin to show more floor. Large-format tiles, a big mirror and good lighting all make a small room read bigger.
In what order do you design and fit a bathroom?
Plan the layout and choose fixtures first, then sequence the trades: first fix plumbing and electrics, then plastering and tiling, then second fix to fit the suite, taps and lights, and finally sealing, flooring and decoration. Locking the layout and ordering everything before work starts keeps the project on time and on budget.
How much does it cost to design a bathroom in London?
Costs vary with the size of the room, the spec of the suite and tiles, and how much plumbing has to move. A simple refit is far cheaper than relocating fixtures or going fully bespoke. Because moving the soil pipe and waterproofing are the big cost drivers, it pays to get the layout and budget right on paper first.
How do you stop a bathroom getting damp and mouldy?
Ventilation is the answer. Fit an extractor rated for the room size, ideally on a humidity sensor or timer, and use it during and after every shower. Add an openable or trickle-vented window where you can, waterproof wet areas correctly before tiling, and use moisture-resistant paint. Good airflow prevents the damp that ruins finishes.