Summary

Wet rooms are the premium specification of UK bathroom design — fully tiled, fully tanked, with the shower draining directly into a floor gully without an enclosure tray. The visual appeal is significant; the technical demand is equally significant. Pricing requires understanding that a wet room is not "a tiled bathroom" — it's a fully waterproofed, gradient-floored, specialist-drainage installation that fails badly if any of the three (tanking, gradient, drain) is wrong.

The most common pricing mistake is treating a wet room as a normal bathroom with a tile-extended floor. The waterproofing membrane (BAL Tank-it, Schlüter-KERDI, Mapei Mapelastic) must cover the entire floor plus 100-150mm up walls; the floor must fall 1:80 to 1:50 toward the drain; the drain must be sized and installed to accommodate full shower flow without backup. Any failure causes water tracking under tiles into joist voids — and remediation costs typically £4,000-£10,000.

This guide covers wet room installations across the typical scenarios — full wet room (no enclosure), partial wet room (walk-in shower zone within a tiled bathroom), and luxury wet room (multiple shower zones, freestanding bath). For standard bathrooms see full bathroom installation pricing guide; for en-suites see en suite pricing guide.

Key Facts

Quick Reference Table

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Wet Room Type Size Spec Cost Range (Regional) Cost Range (London)
Compact wet room 4-5m² Mid-range, point drain, ceramic tile £6,500-£10,000 £8,500-£12,500
Standard wet room 5-7m² Mid-range, linear drain, porcelain tile £8,000-£13,500 £10,500-£16,500
Premium wet room 6-9m² Premium fittings, stone, frameless £14,000-£22,000 £17,500-£28,000
Luxury (double shower, vanity) 8-12m² Premium plus £20,000-£32,000 £25,000-£40,000+
Partial wet zone in bathroom 1.5-3m² shower zone Walk-in only, tray-style £3,500-£6,500 £4,500-£8,500
Wet room en-suite (loft) 3-5m² Compact with linear drain £7,500-£12,500 £9,500-£15,500

Detailed Guidance

The Wet Room Specification

A wet room differs from a standard tiled bathroom in three critical ways:

  1. The entire floor is fully tanked — waterproofing membrane covers 100% of the floor and at least 150mm up every wall (most installs go full-height to the ceiling on the shower wall)
  2. The floor falls to a drain — gradient typically 1:50 to 1:80 toward gully; the entire floor area drains, not just the shower zone
  3. No shower tray or enclosure — water runs straight down the tiled floor; a glass screen (or sometimes no screen at all) prevents splash to adjacent zones

This means:

The Tanking System — Where Wet Rooms Live or Die

Three approaches:

Liquid-applied membrane (BAL Tank-it, Mapei Mapelastic, Sika SikaTop Seal-107)

Sheet membrane (Schlüter-KERDI, Triton)

Cement-based slurry membrane (Mapegum WPS, Ardex 8+9)

For wet rooms in new construction or stable substrates, any of these work. For wet rooms in older buildings with moving timber joists, sheet membrane (Schlüter-KERDI) is the most forgiving choice.

The Drainage Detail

The shower drain must be:

Point drain — single round or square outlet; cheaper; less elegant; typically positioned in shower corner

Linear drain — slot-style channel; runs along one wall of the shower zone; elegant; better for multi-jet shower systems; more expensive

Wall drain — drain integrated into wall at floor level; very modern appearance; specialist install

For a typical wet room, the linear drain (£180-£600 supplied) is now standard mid-range; point drains (£100-£250) are for budget installs.

The Floor Fall — Two Methods

Site-formed fall — applied as part of the substrate. Backer board cut on a taper, or layer of dry-mix screed graded with a trowel. Skill-dependent; can take 1-2 days to set out correctly.

Pre-formed tray — engineered foam or composite tray with falls already graded. Cut to size, fixed to substrate. Faster install (4-6 hours), less skill-dependent. Best for retrofit where the substrate is uneven.

Cost: site-formed adds 1-2 days plumber labour (£480-£700); pre-formed tray adds £200-£500 in materials but saves labour.

Stage Breakdown for a 6m² Wet Room

Day 1-2: Strip and prep

Day 3-4: First-fix plumbing and electrics

Day 4-5: Floor fall and substrate

Day 5-7: Tanking

Day 7-10: Tiling

Day 10-12: Second-fix and snag

Total: 10-14 working days for a standard 6m² wet room. Premium installs run 12-16 days.

Pricing Walkthrough — 6m² Mid-Range Wet Room, Regional

Item Cost
Wet room kit (linear drain + tanking + former) £900
Mid-range porcelain tile (6m² floor + 10m² wall = 16m² × £65) £1,040
Tile adhesive, grout, sundries £200
Tile backer board (12m² walls) £350
Wall-hung toilet + frame £750
Wall-hung basin + tap £500
Thermostatic shower mixer + head £550
Walk-in shower screen (1m frameless) £700
Electric UFH mat (6m²) + thermostat £200
Vanity unit £450
Heated towel rail £180
Extractor fan (Building Regs) £100
Plumber 6 days £1,800
Tiler 4 days (premium) £1,040
Electrician 1.5 days £510
Carpenter 1.5 days £360
Decorator 0.5 day £120
Skip hire + disposal £450
Building Notice + inspection £250
Margin 20% £1,940
Total £12,390

Common Failure Modes (And How to Avoid Them)

Frequently Asked Questions

Is a wet room more expensive than a normal bathroom?

Yes — typically 20-40% more for an equivalent specification because of the tanking, drainage, and specialist tile work. The premium is justified by aesthetic and functional benefits (no enclosure, easy access). For accessibility-driven installs (level access for wheelchair users), the wet room is often the only practical solution.

Will a wet room work in an upstairs bathroom?

Yes — most modern wet rooms are installed upstairs. The waterproofing must be done correctly to prevent leaks to the ceiling below. Insurance is rarely affected; some insurers specify professional installation (which most insurers consider standard practice).

Do I need a special drain for a wet room?

Yes — a standard shower tray drain is not suitable. You need a wet-room-rated drain (gully or linear) with manufacturer-specified flange detail to seal to the tanking membrane. Cost: £100-£600 supplied.

Can a wet room work with a wooden floor?

Yes, but requires careful design. The floor must be reinforced (no joist deflection over the tanked area), substrate must be moisture-resistant backer board, and movement joints designed to handle thermal/moisture movement. Pre-formed trays (Easyflow, ATA) are designed specifically for wooden floor retrofit and reduce risk.

How long does a wet room take to install?

10-14 working days for a standard 6m² installation. Premium installs with stone tile or specialist features 12-16 days. Allow 2-3 days for tanking to fully cure before tiling.

What's the cheapest wet room option?

A compact 4-5m² wet room with ceramic tile, point drain, basic thermostatic shower and standard fittings: £6,500-£10,000 regional. Below this typically involves cutting tanking or substrate corners that will fail within 5-10 years.

Regulations & Standards