How do I know if a builder is overcharging me?

The clearest signal is a quote you cannot verify: a lump sum with no breakdown of labour and materials. Once a quote is itemised, you can sanity-check each line. The labour should reconcile to a believable number of days at a normal regional day rate; materials should sit within roughly 10–20% of trade prices; and the total should not be a dramatic outlier against other quotes for the same scope. A single high line is not proof of overcharging, but three or more together usually is.

What is a normal builder’s markup in the UK?

A general builder typically adds 15–25% to cover overheads and profit (van, insurance, tools, admin, tax, and margin), plus a separate 10–20% markup on materials they supply. Markups meaningfully above those bands are not automatically unfair, but they should be explained by something concrete: a premium specification, an insurance-backed guarantee, or unusually difficult access. Markup with nothing to show for it is the thing to question.

Why is one quote so much higher than the others?

Usually one of three reasons: the dearer builder has priced a higher specification, has included items the cheaper quotes excluded (scaffolding, making good, Building Regs fees), or carries costs the others do not (proper insurance, employed rather than cash-in-hand labour, a real warranty). It can also simply be overpriced. The way to tell them apart is a line-by-line comparison on a like-for-like scope, not a comparison of headline totals.

Is it worth paying more than the cheapest quote?

Often, yes. A 15–25% premium for a detailed, itemised quote with proper insurance and a written warranty is frequently better value than the cheapest quote, which may be missing scope that returns later as variations. The cheapest number on the day is not always the cheapest project at the end. What you are checking is whether the premium buys something real.

Should builders break down labour and materials?

Yes. An itemised quote that separates labour, materials, and overheads is the single best protection a homeowner has. It lets you verify the price, compare quotes fairly, and hold the builder to the agreed scope if extras are later claimed. A builder who refuses to itemise is not necessarily dishonest, but they are removing your ability to check, which is its own reason for caution.

Are builders more expensive in London?

Genuinely, yes. London labour typically runs 15–25% above the national average, sometimes more in inner London. The problem is that this premium is sometimes used to justify a quote that is high even by London standards. A fair London quote is benchmarked against London rates; an unfair one uses "it’s London" to wave away a figure that is above the London market too.

How to tell if a builder’s quote is too high

Eight practical signals that a UK builder’s quote is above a fair price, the legitimate reasons a higher quote can still be the right one, and how to sanity-check the figure before you commit a deposit.

A homeowner reviewing a printed builder’s quote at a kitchen table. — Photo by Romain Dancre on Unsplash

A high quote is not the same as an unfair one. Some of the most expensive quotes are the fairest, because they include the work the cheaper ones quietly left out. The question is never just "is this number big," it is "can I account for the number." This guide is about how to account for it.

Most homeowners have no reference point for what building work should cost, so a quote arrives and the only test available is a gut feeling. That is exactly the gap a small number of builders price into. Below are the eight signals that a quote is above a fair price, followed by the legitimate reasons a high quote can still be the right one.

1. There is no breakdown#

The most common sign of an unfair price is a price you cannot check. "Kitchen extension: £42,000" tells you nothing. A fair quote separates labour, materials, and overheads, and shows what is included and excluded. Without that, you cannot tell whether the figure is fair, and neither can anyone else you ask. If a quote arrives as a single lump sum, the first step is to request an itemised version before drawing any conclusion about the total.

2. The labour does not reconcile#

Once labour is broken out, it should reconcile to a believable number of days at a normal regional day rate. A general builder’s day rate sits in regional bands; a quote that implies 40 days of labour for a job that should take 15 is either padded or hiding materials cost inside the labour line. Work backwards: days times rate should land near the labour figure. If it does not, ask the builder to explain the gap.

3. Materials are marked up beyond the norm#

Builders mark up materials they supply, typically by 10–20%, which is fair: they collect, store, transport, and return the surplus. A markup well beyond that, or a materials figure far above what the same items cost at a builders’ merchant, is worth questioning. You can spot-check a few big-ticket items (units, worktops, boilers, windows) against retail prices to see whether the materials line is in a sensible range.

4. The total is a dramatic outlier#

If you have three quotes and one is 30% or more above the others on the same scope, that gap needs an explanation. Sometimes it is a genuinely higher specification or included items the others left out. Sometimes it is simply overpriced. The outlier is not automatically wrong, but it is automatically worth interrogating line by line. See our guide on why three builder quotes can be so different for the legitimate causes.

5. Allowances and provisional sums are vague or inflated#

A provisional sum is a placeholder for an item whose spec is not yet decided (tiles, kitchen units, sanitaryware). Two failure modes inflate the real cost: allowances left undefined ("tile allowance: TBC"), and allowances set so high that the headline already carries fat. A fair quote names each allowance with a specific figure, for example "tiling: £40/m² inclusive of materials and fitting," so you can judge it.

6. Open-ended phrases let the price drift#

"Works as necessary," "subject to site conditions," "additional materials at cost" with no ceiling. These phrases quietly convert a fixed-price quote into an open one, where the final figure is whatever the builder decides later. A fair fixed-price quote defines its boundaries and states what would trigger a variation, rather than leaving the door open by default.

7. The premium buys nothing you can point to#

A higher quote should come with a reason you can see: a better specification, an insurance-backed guarantee, longer warranty, employed rather than cash-in-hand labour, or genuinely difficult access. When a quote is high and the builder cannot point to anything concrete that justifies it, the premium is just margin. Ask directly what the extra cost is buying. A fair builder will have an answer.

8. "It’s London" (or "it’s a specialist") doing too much work#

Regional and specialist premiums are real. London labour runs 15–25% above the national average. But a genuine premium is benchmarked against the right market; an unfair one uses the label to wave away a figure that is high even for that market. The test is whether the quote is fair against London rates, not whether London is expensive in general.

The legitimate reasons a quote is high#

Before you walk away from the dearest quote, rule these in:

Higher specification. Better materials, a more durable finish, or a more complex design genuinely cost more.
Included scope the others excluded. Scaffolding, making good, Building Regs fees, skip hire, and waste removal are often left out of cheaper quotes and added later. The dearer quote may simply be honest.
Proper insurance and a real warranty. Public liability cover and an insurance-backed guarantee cost the builder money, and protect you.
Regional and access factors. A genuine London or specialist premium, or a site that is hard to reach, raises the fair price.
A busy builder pricing to deter. Established trades sometimes quote high because they do not need the work. That is a high price, not an unfair one.

A quote that is high for a reason you can see is usually fine. A quote that is high for no reason you can find is the one to question.

Cross-check against real ranges#

Each of your line items can be compared against a real UK range. For the common jobs, start with the relevant cost guide:

Compare the quoted total and the big line items against the ranges. If your quote sits inside the range and is itemised, it is probably fair. If it sits above the top of the range with no clear reason, that is your signal to push back.

The two-minute fairness test#

Before you commit a deposit, run this:

Is the quote itemised (labour, materials, overheads shown)?
Does labour reconcile to a believable number of days at a normal rate?
Are materials within roughly 10–20% of trade prices on the big items?
Is the total within the range for this job in your area?
Are allowances and provisional sums named, not vague?
Is the quote free of open-ended "as necessary" phrasing?
If it is the dearest quote, can you point to what the premium buys?

A quote that passes all seven is very likely fair, even if it is not the cheapest. A quote that fails three or more is the one to challenge before any money moves.

Still not sure? That is exactly what Check the Quote is for. Paste or upload your quote and we check every line against current UK market rates for your postcode, flag what sits above the fair range, and tell you what to push back on. Your first check is free.

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Paste any UK contractor quote and Check the Quote compares every line item against current market rates, flags missing scope, and runs a Companies House check on the contractor. Free on your first project.

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Frequently asked questions

How do I know if a builder is overcharging me?: The clearest signal is a quote you cannot verify: a lump sum with no breakdown of labour and materials. Once a quote is itemised, you can sanity-check each line. The labour should reconcile to a believable number of days at a normal regional day rate; materials should sit within roughly 10–20% of trade prices; and the total should not be a dramatic outlier against other quotes for the same scope. A single high line is not proof of overcharging, but three or more together usually is.
What is a normal builder’s markup in the UK?: A general builder typically adds 15–25% to cover overheads and profit (van, insurance, tools, admin, tax, and margin), plus a separate 10–20% markup on materials they supply. Markups meaningfully above those bands are not automatically unfair, but they should be explained by something concrete: a premium specification, an insurance-backed guarantee, or unusually difficult access. Markup with nothing to show for it is the thing to question.
Why is one quote so much higher than the others?: Usually one of three reasons: the dearer builder has priced a higher specification, has included items the cheaper quotes excluded (scaffolding, making good, Building Regs fees), or carries costs the others do not (proper insurance, employed rather than cash-in-hand labour, a real warranty). It can also simply be overpriced. The way to tell them apart is a line-by-line comparison on a like-for-like scope, not a comparison of headline totals.
Is it worth paying more than the cheapest quote?: Often, yes. A 15–25% premium for a detailed, itemised quote with proper insurance and a written warranty is frequently better value than the cheapest quote, which may be missing scope that returns later as variations. The cheapest number on the day is not always the cheapest project at the end. What you are checking is whether the premium buys something real.
Should builders break down labour and materials?: Yes. An itemised quote that separates labour, materials, and overheads is the single best protection a homeowner has. It lets you verify the price, compare quotes fairly, and hold the builder to the agreed scope if extras are later claimed. A builder who refuses to itemise is not necessarily dishonest, but they are removing your ability to check, which is its own reason for caution.
Are builders more expensive in London?: Genuinely, yes. London labour typically runs 15–25% above the national average, sometimes more in inner London. The problem is that this premium is sometimes used to justify a quote that is high even by London standards. A fair London quote is benchmarked against London rates; an unfair one uses "it’s London" to wave away a figure that is above the London market too.

Last updated: 22 May 2026

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