Wet Room vs Bathroom: Costs, Pros & Cons

A wet room is not simply a shower without a tray, it is a waterproofed room where the entire floor acts as a drained surface. That distinction drives nearly every decision about cost, construction, and suitability. This guide covers what a wet room actually requires structurally, what it costs relative to a conventional bathroom, and the honest pros and cons for UK homes.

What Is a Wet Room?

In a wet room, there is no shower tray or enclosure. The floor is graded (typically 1:80–1:60 fall) towards a linear channel drain or a point drain recessed into the floor surface. The entire floor and lower walls, usually to a height of at least 1,800 mm, sometimes floor-to-ceiling, are fully waterproofed (tanked) before any tiling. A glass screen or panel deflects spray but is not a sealed enclosure.

This is fundamentally different from a “walk-in shower” built on a low-profile tray (15–40 mm height) with an open front. That type of installation does not require full-room tanking.

Key structural requirements:

• Floor substrate: Timber joists require a movement-resistant board (cement-particle board, e.g. Fermacell or Hardiebacker) before waterproof membrane application. Concrete is more straightforward.
• Falls: The gradient must be formed in the screed or in a pre-formed wet room former (a manufacturer-formed tray substitute that creates the fall without screeding).
• Drainage: A linear drain across the shower zone’s far edge or a point drain in the floor. Approved Document H sets a shower trap at 40 mm diameter with a 50 mm depth of water seal (the 75 mm seal often quoted is the washbasin and sink figure), and a branch pipe serving one appliance should be at least the diameter of its trap.¹ A fall of around 1:40 on the branch is normal fitting practice rather than a stated minimum.
• Waterproof membrane (tanking): A two-coat liquid membrane or sheet tanking system bonded to the substrate, overlapping into drainage fittings and sealed at wall junctions.

Tanking: The Critical Step

Tanking is what makes a wet room work and what makes it cost more than a standard bathroom. It is not optional and it cannot be skimped.

The two main systems are:

Liquid applied membranes (e.g. BAL Waterproof+ Adhesive, Wedi, Schlüter-KERDI-BAND), applied with a roller or trowel in two coats, glass-fibre tape at all corners and junctions. Sets in 1–6 hours per coat. Most commonly specified by UK bathroom fitters.

Sheet tanking (e.g. Wedi board, Schlüter-KERDI), rigid foam panels bonded directly to the substrate; jointed and sealed. More expensive in materials but faster to tile over and more tolerant of movement.

Tanking costs (supply + labour, 2026 UK):

These figures assume a standard 2–4 m² bathroom. The higher-end sheet systems are worth specifying in timber-frame buildings or upper floors where movement is a concern.

Wet Room Cost vs Bathroom Cost

The total installed cost depends heavily on scope, materials, and what the room currently contains. These are 2026 UK ranges for a typical 3–5 m² room.

What drives the wet room premium over a standard bathroom:

• Full-room tanking: £500–£1,500 extra
• Pre-formed wet room former or screeded fall: £300–£800 extra (versus no screed work needed with a standard tray)
• Linear channel drain: £80–£350 supply-only (versus £40–£120 for a standard shower waste)
• Frameless or semi-frameless glass panel: £200–£700 (versus framed enclosure at £100–£300)

The gap narrows if you are also choosing a walk-in shower configuration in the bathroom, a low-profile tray, open front, and fixed glass panel can approach wet-room aesthetics for less total cost.

Pros of a Wet Room

Accessibility. No step to enter. Part M of the Building Regulations makes the link explicit, but only in one place: in a Category 3 wheelchair user dwelling, every room containing an installed level access shower has to be built as a wet room (paragraph 3.36c). That volume applies to newly erected dwellings and material alterations only, and M4(3) bites only where a planning condition imposes it, so it is not a rule that reaches a bathroom refit in an existing house.² If you are renovating for accessibility or planning ahead, a wet room is still often the right choice.

Cleaning. Without a tray, enclosure frame, and associated silicone seals, there are fewer horizontal surfaces to collect soap scum. The floor tiles and drain are easy to clean, and there are no track grooves.

Space efficiency. In very small rooms (under 2 m²), eliminating a shower tray and enclosure frees floor area perceptibly. A wet room can function in 900 × 900 mm of designated shower zone with the remaining floor kept dry by a screen.

Visual simplicity. A well-executed wet room reads as a continuous tiled space. This is currently the dominant aesthetic in high-end bathroom design in the UK.

Longevity of the shell. Properly tanked substrates with quality tiles and grout are highly durable, the assembly itself can last 25–40 years if maintained. There are no plastic tray mouldings to crack or enclosure seals to replace.

Cons of a Wet Room

Higher installation cost and skill requirement. Tanking must be done correctly. A failed waterproof membrane in an upper-floor wet room will eventually cause structural damage to the floor below. This is not a project for a builder who has not done it before. Always ask for examples of previous wet rooms and check that tanking is being applied at corners, around the drain, and to the specified height.

Not suitable for all timber floors. Building on timber joists introduces movement risk. While this can be mitigated with cement-particle board and a flexible tanking system, it requires proper specification and execution. Some bathroom fitters will decline to install a wet room on a ground-floor timber joist deck.

Condensation and moisture. A wet room produces significantly more steam than a bath. Extraction must be upgraded: Approved Document F sets an intermittent extract rate of 15 l/s for a bathroom, and where a wet room has no external wall the fan has to achieve four air changes an hour instead.³ Part F asks for no more than 15 l/s, but a 30 l/s fan is the sensible specification for a room where the whole floor gets wet. Inadequate extraction leads to mould and deterioration of the tanking system from the outside inward.

Water spread. Without a full enclosure, water does spread beyond the shower zone. A large fixed glass panel (600–900 mm minimum) manages this but does not eliminate it entirely. Heated towel rails and toilet roll holders outside the shower zone should be positioned with this in mind.

Resale and perception. Most buyers understand wet rooms, but some, particularly those with young children, prefer a conventional bath. In a house with a single bathroom, removing the bath entirely can be a minor negative for resale. In a property with two bathrooms, it is rarely an issue.

When to Choose a Wet Room vs a Bathroom

Building Regulations

A wet room installation typically triggers several notifiable elements:

• Part P (electrical): Installing a new circuit is notifiable wherever it runs. Adding to or altering an existing circuit is notifiable only inside a “special location”, which Approved Document P defines as the space from floor level up to 2.25 m and out 0.6 m from the edge of a bath or shower tray, or 1.2 m from the centre of the shower head where there is no tray, which is the case in most wet rooms.⁴ Notifiable work goes to a registered competent person or to the local authority Building Control.
• Part F (ventilation): Mechanical extraction to outside, minimum 15 l/s intermittent for a bathroom (30 l/s is the sensible specification for a wet room). A 15-minute overrun timer is required only where the room has no openable window.³
• Part B (fire): Not usually relevant for internal bathroom conversions, but if the wet room is being created by converting a bedroom in a flat above commercial premises, check with Building Control.
• Party Wall Act: Not normally applicable unless structural work is involved.

No planning permission is required for a wet room conversion in an existing domestic bathroom in England, unless the property is listed.

The rules in this note are those that apply in England. Scotland, Wales and Northern Ireland have their own building standards and permitted development rights.

A wet room is the right choice when accessibility, aesthetics, and budget align. The installation premium over a standard bathroom is real but moderate, typically £1,000–£3,000 extra for an equivalent specification, and is recovered in cleaning ease and longevity. The critical decision is specification: the waterproof membrane and drainage are where wet rooms succeed or fail, and neither is a place to cut corners.