Wet Room Cost Calculator
Wet rooms are priced by what happens under the tiles, not on top of them. This prices the tanking, the fall and the floor build-up that quotes usually bury.
Open the calculator →Price your wet room in 30 seconds
5 steps. Size, spec, floor structure, drainage and region.
How this calculator works
A wet room is a waterproofing job with a bathroom on top. The tanking membrane, the fall to the drain and the floor build-up are what separate a wet room that lasts twenty years from one that marks the ceiling below within two.
That is why the floor question matters most. On concrete the fall is cut into screed. On timber joists it usually means notching or dropping the deck, and upstairs over a finished room there is least space to do it and most to lose.
On certification: bathroom electrics are notifiable under Part P. We do not verify that for you — ask who is certifying the electrical work and get the certificate before you pay the final invoice.
Wet room cost by size and spec (2026)
| Wet room type | Typical 2026 cost | Notes |
|---|---|---|
| Cloakroom / small en-suite (2–3 m²) | £3,800–£6,500 | Shower only, compact layout |
| Standard family bathroom (4–6 m²) | £6,500–£14,000 | The most common conversion |
| Large / master wet room (7–10 m²) | £9,500–£19,000 | Often twin drainage |
| Accessible / level-access (4–6 m²) | £5,500–£13,000 | Grants may cover part of it |
| Tanking / waterproof membrane | £600–£1,500 | Room size; liquid vs sheet |
| Sloped former or screed-to-fall | £250–£700 | Pre-formed tray vs hand-cut screed |
| Floor structure alterations | £0–£1,800 | Timber joists often need notching |
Figures match our wet room cost guide. Bathroom electrics are notifiable under Part P — ask who is certifying.
Wet room calculator FAQs
Because the whole floor becomes the shower tray. Tanking, a fall to the drain and often structural work to the floor are all needed before a single tile goes down.
Most can, but timber floors upstairs are the constraint — you need enough depth to create the fall without weakening the joists. An installer who does not ask about the floor has not priced it.
Not usually for the waterproofing itself, but moving the soil stack often needs building control, and the electrics are notifiable under Part P either way.
Eight to fourteen days for a small one, up to sixteen for a large or luxury build. Tanking and screed both need drying time that cannot be rushed.
Related cost guides
- Wet room cost guide — every line item priced
- Full bathroom costs — every size and spec tier
- Planning a wet room — step by step
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