Bathroom Renovation Cost London: Full Refit Price Guide (2026)

Bathroom renovation cost in London by tier

Bathroom renovation cost splits into three broad tiers, and room size affects each tier differently. A budget refresh keeps the existing layout and plumbing positions in place, replacing the suite, retiling over a sound existing substrate, and refreshing electrics without rewiring the whole room. A mid-range full refit strips the room back to brick and joist, replumbs in the same or a slightly adjusted layout, tanks the wet areas properly, and fits new tiling, sanitaryware and electrics throughout. A premium wetroom or ensuite conversion goes further again, usually involving a layout change, a wetroom floor built to falls rather than a standard shower tray, underfloor heating and higher-specification fittings.

These figures are general London market guidance rather than a fixed Lian Construction quote. A small ensuite and a full family bathroom sit at different price points within each tier, which the table below sets out separately, since room size changes the total far less than most people expect once plumbing, tanking and electrics are accounted for.

Small ensuite vs full family bathroom: why size doesn't scale cost evenly

A small ensuite squeezed into a boxroom or the end of a landing can sometimes cost more per square metre than a considerably larger family bathroom, and this catches people out when they're budgeting by room size alone. The reason is that plumbing, tanking and electrical work carry largely fixed costs regardless of room size: running new hot and cold supplies, forming a waste run with the correct fall, tanking the wet zones to BS 5385, and wiring a zone-rated light and extractor fan all take a similar amount of time whether the room is 2 square metres or 8.

Tiling and sanitaryware are the parts of the budget that genuinely scale with room size, since a bigger room needs more tiles and, often, larger or additional sanitaryware. That's why the gap between an ensuite and a full family bathroom narrows in percentage terms once you move from a budget refresh, where tiling area is the main cost variable, to a premium wetroom conversion, where plumbing, tanking and electrics dominate the budget regardless of the room's footprint.

Why moving plumbing costs more in a London flat than in a house

One of the most consistent and least understood cost differences in London bathroom renovation is the type of floor construction behind the walls. A typical London house, particularly a Victorian or Edwardian terrace, has suspended timber floors, meaning waste pipes and supply runs can be routed between the joists, with sections of floorboard lifted, the pipework run through notched or drilled joists within Building Regulations limits, and the boards relaid afterwards. It's disruptive but relatively straightforward work for an experienced plumber.

A London flat, particularly a purpose-built or ex-council block, more often has a solid concrete floor slab between storeys. Cutting a deep chase into a structural concrete slab to move a waste run isn't something a responsible contractor does, since it can compromise the slab's structural integrity and, in a building with flats above and below, affect a neighbour's ceiling too. Instead, moving a WC or shower to a new position in a flat usually means building a raised floor void, boxing in a duct along a wall, or running new pipework through a false ceiling in the room below, all of which add cost, height and, in some cases, a conversation with the flat below or the freeholder. As a rough guide, relocating a WC or shower waste run typically adds £800 to £1,500 to a house renovation with suspended timber floors, against £1,500 to £3,000 or more for the equivalent change in a concrete-floored flat.

This is a genuine, structural reason to think carefully about keeping the existing layout in a flat renovation wherever possible, rather than assuming a house-based budget figure will translate directly. Our bathroom renovation London team checks floor construction at survey stage before pricing any layout change, since it's one of the biggest single variables in the quote.

Waterproofing, tanking and electrics cost

Tanking, the waterproof membrane behind the tiles in a shower enclosure, around a bath and beyond a basin splash zone, typically adds £400 to £900 to a standard bathroom as part of a mid-range or premium refit, using either a liquid membrane rolled on in coats or a bonded sheet membrane taped at joints. A full wetroom floor, built to fall towards a drain with a tapered former or screed and membrane taken across the whole floor rather than just around a tray, costs more again, typically £900 to £1,800 depending on room size and drain type, since getting the falls right is a slower, more exacting job than dressing a membrane up around a standard shower tray.

Electrics in a bathroom are governed by zoning rules under BS 7671, which restrict where sockets, switches and certain light fittings can sit relative to the bath or shower, and any work here is notifiable under Part P of the Building Regulations. A standard bathroom rewire with zone-rated lighting, a shaver socket and an extractor fan typically costs £600 to £1,200 as part of a wider refit; adding underfloor heating, which needs coordinating with the electrician for a separate circuit, typically adds £400 to £900 depending on room size.

What pushes bathroom renovation cost up or down

Timeline and planning permission for bathroom renovation

A like-for-like refit, replacing the suite and tiling without moving pipework, typically takes one to two weeks. Where the layout is changing, three to four weeks is more realistic once tanking cure times and any floor build-up are accounted for. Most internal bathroom renovation work does not need planning permission, since it doesn't change the external appearance of the property, but building regulations apply to electrical work under Part P, to ventilation under Part F, and to any structural change to floor joists where pipework is being relocated.

In a leasehold flat, a licence to alter from the freeholder or managing agent is often required before renovation work starts, even for internal-only work, in the same way it applies to a wider flat renovation. It's worth applying in parallel with getting quotes rather than after, so the renovation programme isn't held up waiting for consent once a contractor is ready to start. Our tiling team works to the same waterproofing standard across both bathroom renovations and standalone retiling projects, so a bathroom that only needs new tiles rather than a full refit isn't priced or specified any less carefully.