5 Signs Your Bathroom Renovation Quote Is a Scam

1. The quote has no separate line for waterproofing and tanking

Ask any bathroom fitter for a breakdown of a quote and you should get separate figures for labour, for sanitaryware and tiles, and for waterproofing and tanking as its own line item, not folded silently into a general 'labour' or 'materials' figure. Waterproofing is the one part of a bathroom that decides whether the room actually works once it's finished, and it's also the one part nobody, including you, can inspect once the tiles are on. That combination, invisible now and expensive to fix later, is exactly what makes it the easiest place for a quote to save money without the saving ever showing up at handover.

A single lump-sum figure with no breakdown hides whether a genuine waterproof membrane and zoned tanking to a recognised standard such as BS 5385 has actually been priced in at all, or whether the fitter is planning to rely on a couple of coats of tanking paint applied quickly before tiling starts. Both look the same on the day the room is finished. The difference only shows up months later, as a damp patch on a ceiling below, a musty smell building up behind a stud wall, or grout darkening at the base of the shower years before it should.

If a fitter can't or won't say what proportion of the quote covers waterproofing specifically, that's not a paperwork gap, it's a sign the tanking hasn't been costed as its own piece of work with its own time and materials, which is usually the first thing to get squeezed when a job is running behind schedule or a fitter is trying to win the work on price alone.

2. The deposit is more than a quarter of the job

Bathroom renovation is one of the more common categories of 'took the deposit and disappeared' complaint, and the reason is specific to how the job is put together. Sanitaryware, tiles and a new suite can be bought relatively cheaply and quickly, so a fitter taking a large deposit has effectively already covered the visible, easily priced part of the job before doing any of the labour-intensive, hard-to-check work: strip-out, first fix, and waterproofing. That's the part of the job that's easiest to skip or rush, and it's also the part a large upfront deposit has already been paid for regardless of whether it happens properly.

A deposit above roughly a quarter of the total contract value, taken before the old suite has even come out, shifts nearly all of the financial risk onto you before you have any evidence of how carefully this particular fitter works on your particular bathroom. A reasonable structure stages payment against completed work: a modest amount to secure the booking and order materials, then further payments tied to strip-out, first fix and tanking, tiling, and final fit and handover, so the fitter is only ever paid for work that's actually been done and can be checked at each stage.

If a fitter pushes for most of the contract value upfront and points to the cost of materials as the reason, it's worth noting that sanitaryware and tiles can usually be invoiced and paid for as a distinct, smaller stage rather than bundled into one large payment that also covers labour that hasn't happened yet.

3. Nobody mentions testing the waterproofing before tiling

A properly tanked shower area or wetroom floor should be tested before the tiles go down, not simply assumed to have worked. Flood or pressure testing means filling the tanked area with a set depth of water and leaving it for a defined period while checking underneath and around for any sign of a leak, catching a poorly formed fall or a compromised membrane while it's still possible to fix without lifting finished tiling. This is standard, well-understood practice on a wetroom floor specifically, and good practice on any shower area more generally, precisely because a membrane can look fine to the eye and still fail once it's under continuous water exposure.

If testing isn't mentioned anywhere in a quote or conversation, ask directly whether the waterproofing will be tested before tiling and what that test involves. A fitter who tests as standard will usually describe it readily and be able to say roughly how long it takes, because it's a normal part of their process. A fitter who's never heard of testing, or treats the question as unnecessary because 'the tanking's fine', is telling you that nobody is going to check the one part of the job that matters most before it's permanently covered over.

Skipping this step doesn't save meaningful time on a well-run job, since tanking has to cure anyway before tiling starts. It mostly saves the fitter from finding out, and having to fix, a problem before it becomes yours to live with.

4. The quote is significantly below every other quote for the same scope

Bathroom renovation has one of the widest quality gaps in construction between a budget job and a properly specified one, for a room that can look almost identical in photos taken on completion day. Two fitters can quote for what looks like the same scope, strip out, tank, tile, fit a new suite, and arrive at genuinely different prices because one has priced proper tanking, testing, and time to let materials cure properly, and the other hasn't. The visible finish, tiling lines, grout colour, sanitaryware, can look equally good in both cases on the day. What's different is everything underneath and behind it, which is exactly the part you can't judge from a finished photo.

A quote that comes in dramatically below the others you've collected for the same scope, particularly by something like a third or more, is far more likely to reflect what's been left out than genuine efficiency or a fitter working for less profit. The honest way to check is to ask each fitter, in writing, to confirm exactly what waterproofing standard they're working to, whether it's tested before tiling, and what the deposit and payment stages look like, then compare those specific answers rather than just the bottom line. A fitter with nothing to hide will answer plainly; one relying on a bare price to win the job often won't.

This doesn't mean the cheapest quote is always wrong, sometimes a fitter genuinely is more efficient or carries lower overheads. It means a large gap needs an explanation beyond 'we're just cheaper', and that explanation should be checkable against what's actually written into the scope rather than taken on trust.

5. There's no written guarantee that specifically covers the waterproofing

A workmanship guarantee that only covers 'the bathroom' in general terms, without saying anything specific about tanking or waterproofing, isn't much protection if a leak shows up eighteen months later behind a shower wall. Visible tiling defects, a cracked tile, a badly cut edge, are the kind of thing most fitters will happily put right without much argument, because they're cheap and quick to fix and obviously their responsibility. Waterproofing failure is different: it's expensive to diagnose, expensive to fix because tiling usually has to come off to get at it, and it's exactly the kind of claim a fitter with a vague guarantee can argue was caused by something else, movement, plumbing, a leak from upstairs, rather than accept responsibility for.

Ask specifically what the guarantee covers if water gets through the tanking rather than just the visible tiling, and get the answer in writing as part of the quote, not as a verbal reassurance given at the point of booking. A fitter confident in their own tanking work has no reason to avoid putting that commitment on paper, since it's exactly the outcome they're already expecting.

We agree workmanship cover as part of the written quote before work starts on every bathroom we take on, with the period depending on the scope of tanking and tiling involved, and we test wetroom floors and shower waterproofing before tiling wherever practical for the reasons set out above. It's worth using the same standard to judge any quote you're comparing against ours, from us or anyone else.

What a genuine bathroom renovation actually costs in London

None of this means a bathroom renovation has to be expensive to be legitimate, budget refits at the lower end of the market are entirely genuine work. What matters is whether a low price still has proper waterproofing, testing and a written guarantee built into it, or whether it's low precisely because those have been left out. The table below sets out typical 2027 London ranges for straightforward, honestly specified work, grounded in the same figures published across our bathroom renovation cost guide, so you've got something concrete to check a quote against rather than guessing at what's reasonable.

Getting a bathroom renovation quote you can trust

None of these five signs on their own proves a quote is dishonest, and a fitter can have a perfectly reasonable explanation for one of them in isolation. It's the combination that matters: a lump-sum quote with a large deposit, no mention of testing, and a vague guarantee, priced well below everyone else, is a genuinely different proposition to a similar-looking quote that answers all of these questions plainly and in writing. Our bathroom renovation London team breaks quotes down by category, tests waterproofing before tiling, and puts workmanship cover in writing before work starts, and we're happy to be checked against the same questions covered here. For the wider checklist that applies to any building work, not just bathrooms, see our guide on how to tell if your builder is trying to scam you.