Will a wet room leak?

Properly installed: no — bonded tanking is the same waterproofing used in swimming pools and rated for permanent water contact. Risk is poor install: missing taping at joints, no membrane behind tile adhesive (relying on tile alone is the most common failure), or settlement cracking floor. Specify 10-year tanking warranty and independent inspection during install in flats.

Wet room or walk-in shower?

Walk-in shower with low-profile tray and 8mm screen achieves 80% of wet room look at 50% of build cost (£3,500–£8,500 vs £8,500–£24,500). Use wet room only if accessibility, large room footprint, or design statement matters more than cost. For flats above other dwellings, walk-in shower with traditional tray is the lower-risk choice.

Can I have a wet room upstairs?

Yes but build-up is significant — 75–110mm above structural deck means raising the floor of the bathroom and creating step or threshold at door. Acceptable in some layouts (separate guest WC), problematic in master bedroom suite where flow matters. Trimming joists deeper or accepting a step are the two routes. Always with full structural calc for the deck and tanking warranty.

Wet Room Design London 2026 | Builderr

How Should a Wet Room Be Designed in a London Home?

A London wet room needs minimum 2.5m² footprint, full bonded tanking (membrane behind tiles), 1:80 fall to a linear drain, drainage capacity 1.6 L/s minimum, ceramic/porcelain or microcement throughout, and underfloor heating to dry the floor between uses. Cost £8,500–£24,500. Acoustic isolation from rooms below mandatory in flats. Screen optional but reduces splash. Best for ground floor or solid concrete floors.

When wet rooms work

Best on: solid concrete floors (waterproofing simpler), ground floor (no leak risk below), large rooms (2.5m²+ with linear drain), accessible/disabled bathrooms (level access). Less suited to: upstairs timber-joist floors in older houses (require deep floor build-up for fall + tanking + screed — typically 75–95mm extra height needed against doorways), small bathrooms below 2m² (water spreads everywhere), flats above other dwellings (leak risk significant). Failed wet rooms in flats are the single biggest source of building insurance claims — tanking failure leaks into neighbour below. Mandatory in flats: 10-year warranty on tanking installer + independent inspection during install.

Construction and tanking

Floor: structural deck (concrete or marine ply on joists with sister-joist reinforcement if span exceeds 2.4m) → 12mm cement backer board → bonded waterproofing membrane (Mapei Mapelastic, Ardex 8+9, Schlüter-Kerdi) covering 100% floor + 200mm up walls → 50mm screed sloped 1:80 to linear drain → tile adhesive → tile. Total build-up 75–110mm above structural deck. Wall: cement board → membrane (200mm above tile + above shower head area) → tile. Linear drain: 600–1,200mm length, located against shortest wall in shower zone, connected to 50mm waste with anti-siphon trap. Ventilation: extract fan 25 L/s minimum continuous OR humidistat-controlled at 60% RH trigger. Fall verification at completion: water poured at far corner reaches drain in under 90 seconds.

Materials and fixtures

Floor tile: large-format porcelain (600×600 or 600×1,200mm) — fewer grout lines means fewer failure points; R10–R11 slip rating mandatory (R11 wet area). Microcement (Diasen, Topciment) increasingly popular: seamless, modern look, £180–£350/m² applied; requires skilled applicator and 4–6mm thickness with sealant top coat. Walls: porcelain to ceiling for waterproofing extension; or tile to 2.1m + painted moisture-resistant ceiling above. Screen: 8mm toughened glass single panel or pivoting screen — eliminates 80% of splash; or fully screenless (true 'wet room' aesthetic). Shower: thermostatic with hand-held + fixed head; minimum 12 L/min flow. Towel rail dual-fuel (heated by central heating in winter, electric only in summer for towel dry).