Wet Room Design and Installation in London: What the Best Look Like

A wet room — a fully tanked, level-access shower space — is one of the most technically demanding elements in residential renovation. When done correctly, it is among the most elegant. When done poorly, it is among the most expensive mistakes a homeowner can make.

This is what a proper wet room installation involves, and what to look for when commissioning one.

What a wet room actually is

A wet room is a bathroom where the shower area is not enclosed by a tray or screen but forms part of the room itself, drained through a floor waste. The entire floor — and typically the lower walls — must be waterproofed to a standard that prevents any moisture penetration into the subfloor and structure.

This is distinct from a walk-in shower, which uses a shower tray to contain water. A wet room has no tray: water drains through the floor directly.

Why wet rooms fail

The failure mode for wet rooms is almost always inadequate waterproofing. Specifically:

• —Incorrect tanking product for the substrate
• —Insufficient coverage or missed areas (particularly corners and junctions)
• —Inadequate fall on the floor — water pools rather than draining
• —Poor quality drain installation — grout-filled gaps around the waste
• —Using standard tile adhesives rather than flexible waterproof alternatives in movement zones

Water ingress in a wet room is typically not visible for months or years. By the time it manifests — staining, cracking, failed tiles, structural damage — remediation is expensive and disruptive. The floor must often be stripped to the subfloor and the entire waterproofing system reinstalled.

The correct waterproofing approach

For residential wet rooms, the current standard is a tanking membrane system applied to the substrate before any tiles or finishes are fixed. The membrane must:

• —Be continuous across the entire floor and up the walls to at least 200mm above the highest water contact point (typically higher)
• —Have corners and junctions taped and reinforced with compatible fabric tape
• —Be applied in accordance with the manufacturer's system — usually two coats, with a defined cure time between coats
• —Be inspection-documented before any tiles are laid

The drain installation must be integral to the membrane — the drain flange is sealed into the membrane system, not just grouted around. This is a detail that is routinely wrong on cheaply installed wet rooms.

Floor falls

For water to drain properly, the floor must fall toward the drain at a minimum gradient of 1:80, and ideally 1:60. In a tiled wet room, this means the tiles must be laid on a screed or substrate that has been formed with the correct fall — not just propped up with adhesive.

Getting the fall right in a wet room requires planning before anything is laid. The drain position determines the fall direction; the substrate must be formed to that gradient from the outset. It cannot be corrected at tile-laying stage without stripping back to the subfloor.

For large-format tiles (which are increasingly popular in luxury wet rooms), the fall must be achieved without visible lippage between tiles. This requires precision screeding and skilled tile-laying. It is one of the most technically demanding aspects of the installation.

Materials and finishes

The finish choices in a wet room have significant practical implications:

Large-format porcelain or stone tiles are the dominant choice in luxury wet rooms. They give a seamless, gallery-like appearance. The challenges: they require very flat substrates, they are heavy (relevant for upper-floor installations), and they need specialist cutting.

Marble and natural stone require additional consideration in wet areas. Marble is porous and must be sealed before use and maintained thereafter. Some stones — particularly calcite-rich marbles — can be damaged by acidic cleaning products or prolonged water contact. If using natural stone in a wet room, specify a sealant appropriate for continuous wet exposure.

Grout selection matters. Epoxy grout is more resistant to staining and moisture penetration than cementitious grout, particularly in high-use wet rooms. The grout joint width should be specified to suit the tile format and substrate tolerance.

Shower glass for wet rooms is typically 10–12mm toughened glass, frameless. Cheap wet room glass at 6–8mm flexes and leaks at seals. The glass should be fixed to a structural wall, not a partition, and the fixings should be stainless steel or solid brass — not plated mild steel which corrodes.

Drainage options

The drain in a wet room is a design element as well as a functional component. The main options:

Point drain: a single waste point, typically in the centre or corner of the shower area. Works well for smaller wet rooms. Requires the floor to fall from all sides to the single point.

Linear drain: a channel drain along one wall. Allows the floor to fall in one direction only, which simplifies tile laying and is often preferred with large-format tiles. Gives a cleaner, more considered aesthetic. The channel must be sized to the volume of water anticipated.

Perimeter drain (slot drain): a very narrow slot drain around the perimeter of the wet area. Highly architectural in appearance; the most demanding to execute correctly.

What a good specification looks like

If you are commissioning a wet room, the specification should include:

• —Named waterproofing system (manufacturer, product reference) with method statement
• —Drain manufacturer, model, and installation method
• —Minimum floor gradient and drain position
• —Tile specification including adhesive and grout references
• —Glass specification (thickness, finish, fixings)
• —Silicone specification for movement joints (type, colour, application method)

If a contractor cannot provide this level of specification before works begin, the installation quality is unlikely to meet a luxury standard.

ASAAN's approach

ASAAN has installed wet rooms in some of London's most demanding residential properties. We specify waterproofing systems by reference to named products and inspect membrane installation before any tiles are laid. We document compliance.

If you are planning a bathroom renovation that includes a wet room, contact us to discuss the correct approach for your property.