How to Plan a Bathroom Wet Room: Step by Step (2026 UK)
A wet room is a fully waterproofed, level-access bathroom where the shower drains straight through the floor — no tray, no step. The three stages that make or break it are tanking (the continuous waterproof membrane), the floor falls toward the drain, and the right drainage. Get these wrong and water finds the room below. Budget £5,000–£12,000 depending on size, floor type and finish. Here’s exactly how to plan one before you book a fitter.
Wet room planning at a glance — 2026 UK
- What it is: a level-access, fully tanked bathroom with an open shower draining through the floor
- Non-negotiables: continuous tanking, correct floor falls (10–20mm per metre to the drain), adequate drainage
- Drainage: point drain + sloped former (simplest) or linear drain + screed-to-fall (sleeker)
- Floor: timber floors need reinforcing + a former; concrete can be screeded to fall
- Must-haves: R10+ non-slip floor tiles, a correctly sized extractor fan, Part P electrics
- Typical cost: £5,000–£12,000 (size, floor type, finish and UFH)
- Timeline: 5–10 working days for a standard conversion
How to plan a wet room (7 steps)
- Confirm the room is suitable. Check the floor structure — timber floors need reinforcing and a sloped former; concrete can be screeded to fall. Confirm the waste can reach a soil stack within a workable run.
- Plan the layout and drain position. Place the drain in the shower zone with the whole floor falling toward it. A linear drain against one wall gives a clean single-direction fall and is easier to get right.
- Choose the drainage and floor build-up. A point drain with a pre-formed sloped tray former is the simplest; a linear drain with screed-to-fall looks sleeker. Aim for a 1–2% fall (about 10–20mm per metre).
- Specify the tanking system. The entire floor and the lower shower-zone walls must be sealed with a continuous waterproof membrane before tiling. This is the single most important step — insist on a tanking guarantee in writing.
- Plan heating, ventilation and electrics. Underfloor heating helps the floor dry between uses; a correctly sized extractor fan controls moisture. All electrics must be installed by a Part P registered electrician to the correct IP zones.
- Select non-slip finishes. Use floor tiles rated R10 or higher (or small mosaics whose grout lines add grip). Tile the walls to at least shower height — full height looks best and protects the plaster.
- Get 3 quotes & confirm building regs. Quote on identical specs. Agree who certifies the electrics and handles any building control notification before work starts.
What a wet room costs in 2026 UK
A small wet room on a concrete floor with a mid-range finish lands around £5,000–£7,000; a larger timber-floor conversion with premium tiles and UFH can reach £10,000–£12,000.
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Frequently asked questions
Tanking is the continuous waterproof membrane applied to the floor and lower walls before tiling. Tiles and grout are not waterproof on their own — the tanking is what actually keeps water out of the structure. It’s the single most important part of a wet room; skipping or rushing it is the leading cause of leaks into the room below.
Yes, but the floor usually needs reinforcing and a pre-formed sloped former designed for timber joists to create the fall and a rigid base. Concrete floors are simpler because they can be screeded directly to fall. A good fitter will assess the deflection of the floor before quoting.
Around 1–2%, or roughly 10–20mm per metre, falling toward the drain. Too little and water pools; too much and the floor feels uncomfortable underfoot and tiles are harder to lay flat. Linear drains against a wall make a consistent single-direction fall easier to achieve than a central point drain.
Converting an existing bathroom into a wet room doesn’t usually need a planning application, but the electrical work falls under Part P and the ventilation under Part F of the building regulations. Use a Part P registered electrician who can self-certify, and make sure the extractor fan meets the required extraction rate.
Point drains with a sloped former are cheaper and reliable but need the floor to fall from all directions. Linear drains sit against a wall or at the threshold, so the floor falls in one plane — easier to tile neatly with large-format tiles and the more popular modern choice. Linear costs a little more.
A standard conversion takes 5–10 working days: strip-out, first-fix plumbing and electrics, floor build-up and former, tanking (with curing time), tiling, then second-fix and finishing. The tanking must fully cure before tiling, so don’t let a fitter rush that stage to hit a deadline.
Sources used
- gov.uk — Building regulations approval (Part P & Part F)
- NICEIC — Find a registered electrician
- BSI — BS 5385 wall & floor tiling standards
Methodology: Cost ranges use representative quote data from BestBuilders’ UK bathroom-fitter network (May 2026). Technical guidance cross-referenced against manufacturer tanking-system specifications and BS 5385. Last fact-checked: .