Planning a Bathroom Renovation in London: Costs, Timescales and What to Expect
A bathroom renovation looks, on paper, like one of the more contained jobs a homeowner can take on. It is a small room, a fixed list of fittings, and a finite number of trades. In practice it is one of the more technically dense projects in a home, because so much of the work happens behind the tiles rather than in front of them. Waterproofing, drainage falls, ventilation and structural loading all have to be right before a single tile goes up, and getting them wrong is expensive to put right once the room is finished.
This guide sets out what genuinely drives bathroom renovation costs and timescales in London, what tends to catch first-time renovators out, and how to plan the project so it runs smoothly from quotation to completion.
Why bathroom renovations are rarely as simple as they look?
Most of the visible cost in a bathroom sits in tiling, sanitaryware and fittings, but most of the risk sits in what you cannot see. Older London properties, particularly conversions and pre-war terraces, often have plumbing runs that were never designed for a modern layout, timber floors that need reinforcing under a heavy bath or shower tray, and extraction that was inadequate even before the renovation started. A contractor who prices only the visible scope, without opening up or at least asking the right questions about the existing services, is pricing a different job to the one that eventually gets built.
This is why a proper site visit and a clear specification matter more in bathrooms than in almost any other room. Decisions about tile size, waterproofing method (tanking versus a wet-room membrane system) and ventilation strategy need to be fixed before work starts, not worked out as the job progresses.
What actually drives the cost of a bathroom renovation?
Costs vary considerably depending on layout changes, fittings and the condition of what is already there. The main drivers are:
- Whether the layout is changing (moving a bath, basin or WC moves waste pipes and drainage falls, which is far more disruptive than a like-for-like swap)
- The waterproofing specification, particularly for walk-in showers and wet rooms
- Sanitaryware and fittings quality, from budget suites to bespoke brassware and natural stone
- Underfloor heating, which adds cost but is often requested in London flats without radiator space
- Electrical work, including shaver sockets, extractor fans and lighting circuits that need to meet bathroom zoning rules
- Access and building constraints, such as period properties, shared pipework in flats, or limited parking for skips and deliveries
None of these are unusual requests. They are simply the reason two bathrooms of the same size can come out at very different prices, and why a specification written down clearly at the outset is worth more than a verbal description of "a nice modern bathroom."
Typical costs for a London bathroom renovation
As a broad guide, a straightforward bathroom refurbishment with no layout changes in London typically starts from around £8,000 to £12,000, covering standard sanitaryware, tiling and redecoration. Where the layout is altered, waterproofing is upgraded to a full wet-room specification, or fittings move towards the higher end, £15,000 to £25,000 is a more realistic range. En-suite additions or complex reconfigurations in period properties can run higher still once structural and drainage work is involved.
These figures are indicative rather than a quotation, and the only reliable way to know what your project will cost is a proper site survey against a written specification.
How long does a bathroom renovation take?
A single bathroom with no structural changes typically takes two to three weeks on site once materials are available, covering strip-out, first-fix plumbing and electrics, waterproofing, tiling, second fix and decoration. Add a week or more where the layout is changing, where underfloor heating is being installed, or where existing pipework needs upgrading. Lead times on tiles, sanitaryware and bespoke joinery often extend the overall programme more than the building work itself, which is why ordering materials early, once the specification is confirmed, is one of the simplest ways to keep a project on schedule.
Structural and plumbing considerations most homeowners miss
Bathrooms carry more weight and more risk of water damage than almost any other domestic room, so a handful of technical checks are worth raising with your contractor before work starts. Floor joists under a stone bath or large format porcelain need checking, particularly in older timber-framed properties. Waste pipe falls need to be correct for the new layout, not simply reused from the old one. Ventilation needs to meet current guidance to control condensation and protect the structure over time. And in flats, altering plumbing that is shared with, or runs near, a neighbouring property may need to be discussed with the freeholder or managing agent before work begins, particularly under a lease that requires a Licence to Alter for this kind of change.
Common mistakes that push bathroom projects over budget
- Choosing tiles or sanitaryware after work has started, causing delays while items are ordered
- Underestimating the cost of moving a WC or shower, which affects drainage falls and sometimes floor build-up
- Skipping a proper waterproofing specification to save cost, which risks far larger repair bills later
- Assuming existing electrics meet current bathroom zoning requirements without having them checked
- Treating the quotation as fixed without agreeing how variations, if needed, will be priced and approved.
Choosing fittings, tiling and finishes
It is worth resisting the temptation to finalise every fitting from a showroom display before the room has been surveyed. Tile size and layout affect how a small London bathroom reads, large format tiles reduce grout lines and can make a compact room feel calmer, while the wrong scale can make it feel busier. Brassware finish, whether polished chrome, brushed brass or matt black, is one of the few genuinely low-cost ways to change the character of the room, so it is worth deciding this alongside the tiling rather than as an afterthought once the budget has already been spent on the bigger items.
Getting quotations you can actually compare
Bathroom quotations are notoriously difficult to compare like for like, because one contractor's "supply and fit" figure may exclude tiling, waterproofing membrane or electrical certification that another has included. Before comparing prices, check that each quotation states the same specification for sanitaryware, tiling, waterproofing method and electrical work, and ask explicitly what is excluded. A lower headline figure that excludes waterproofing or making good is not a cheaper job, it is an incomplete one.
Working with a project manager or main contractor
For a single bathroom, many homeowners manage the project themselves or work directly with a bathroom fitter. For larger or more complex renovations, particularly where plumbing, electrics, tiling and joinery need to be sequenced correctly, a main contractor or project manager who coordinates the trades, holds the programme and manages variations tends to deliver a smoother result with fewer surprises, especially where the bathroom is part of a wider refurbishment.
Bayocorp works with homeowners, landlords and property professionals across London and the South East, providing refurbishment, cost planning, project management and construction delivery.
Renovate | Refit |Refurbish