Sizing
1,000×800mm absolute minimum — feels tight, one user only. 1,200×900mm comfortable — single user with room to manoeuvre. 1,500×900mm generous — two-user capable, accommodates seat. 1,800×900mm+ approaching wet room. Door swing or screen position must not block other bathroom traffic — 'walking past the shower to reach the WC' planning common in compact London bathrooms. Screen 8mm toughened glass with stainless steel or matt black hinges; 10mm for screens above 1,200mm wide unsupported. Single fixed pane (no door) is the cleanest 'walk-in' aesthetic but requires shower head positioned to throw water inward — opposite-wall mounting.
Tray and screen
Low-profile tray: stone resin (Lakes, Mira, Roman) 25–40mm tall, drains through integrated 90mm waste. Cost £350–£950 typical. Anti-slip surface mandatory in family/elderly use cases. Flush-fit (zero-threshold): tray sits flush with bathroom floor, water drains through gully — closer to wet room, slightly more complex install. Screens: 8mm clear glass standard; matt black framing trends 2024–2026; Crittall-style (steel-frame with grid) £950–£2,400 premium. Curved screens for corner showers 'old' aesthetic — straight panel walk-in is current. Screen mounted to wall via stainless brackets or wall channel; floor support via U-channel on tray.
Plumbing and showering
Thermostatic mixer: TMV3-rated for safety (caps max temp at 48°C — critical for children/elderly). Bar mixer mounted on wall at 1,150mm; concealed valve (recessed into wall, plate flush with tile) is the premium aesthetic. Flow: 12 L/min minimum for satisfying shower; rain heads need 15 L/min. Combi boiler check: 28kW+ delivers 12–14 L/min; below this, pressurised cylinder system needed. Hand-held on slide rail 850–1,950mm vertical range; rain head 2,100mm above floor for tall users. Linear drain or gully — drain capacity 1.0 L/s minimum (matches shower flow). Niche shelf in wall for soap/shampoo 1,200mm from floor, 200×400×100mm cavity tiled-in.
