Compare Guide · Updated August 2026 · UK Extensions

How to Compare Kitchen Extension Quotes in 2026: What to Look For

Three builders can quote the same kitchen extension and come back GBP 20,000 apart - not because one is greedy, but because they are pricing different things. A complete quote, a vague estimate and a low-ball all look similar at first glance. This 2026 guide shows exactly what a good quote includes, the red flags that signal trouble, and how to get a true like-for-like comparison so you can pick the best value rather than just the cheapest number.

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Quote checklist
Updated August 2026
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Side by Side · 2026

Good Quote vs Red-Flag Quote

The headline price tells you almost nothing on its own. What matters is what sits behind it. Here is how a complete, trustworthy quote compares with one to be wary of.

FeatureGood quoteRed-flag quote
FormatItemised, written, fixed priceSingle round number, verbal
ScopeLists inclusions and exclusionsVague, no spec referenced
VATStated clearlyNot mentioned
Payment termsStaged against milestonesLarge deposit up front
Insurance & guaranteePublic liability, written warrantyNone offered
ReferencesRecent jobs you can visitReluctant or none

A typical single-storey kitchen extension runs GBP 40,000 to GBP 80,000 in 2026. A quote far below the others usually has gaps that surface as extras mid-build.

What to Look For

The Kitchen Extension Quote Checklist

  • Itemised breakdown: groundworks, structure, roof, glazing, electrics, plumbing, plastering and kitchen fit clearly separated.
  • Defined specification: the quote should reference the same drawings and spec for every builder - same glazing, same units, same finish.
  • Inclusions and exclusions: is the kitchen itself, flooring, decorating and VAT in or out?
  • Provisional sums: allowances for items not yet chosen, so you can compare them honestly.
  • Payment schedule: staged payments against completed milestones, never a large up-front deposit.
  • Insurance and guarantee: public liability cover and a written workmanship warranty or insurance-backed guarantee.
  • Timescale: a realistic start date and programme, typically 10 to 16 weeks for a kitchen extension.
Payment & Protection

Payment Terms and Guarantees

How you pay is as important as how much. Reputable builders stage payments against completed work - for example deposit on start, then payments at foundations, structure, watertight, and completion. Be wary of any builder asking for a large deposit before materials are on site.

For peace of mind, look for a written contract (the JCT Homeowner contract is ideal), public liability insurance, and an insurance-backed guarantee that survives even if the builder ceases trading. These protections are what separate the best-value quote from the merely cheapest.

FAQ · 2026

Comparing Kitchen Extension Quotes FAQs · 2026

Get at least three quotes for a kitchen extension. Three lets you spot an outlier in either direction - a low-ball with hidden gaps or an overpriced quote - and gives you room to negotiate. Make sure all three price the same drawings and specification so the comparison is like-for-like.
Usually because the builders are pricing different scopes. One may exclude the kitchen units, flooring or VAT, use cheaper glazing, or assume simpler groundworks. Differences in overheads, current workload and risk allowance also play a part. Always check inclusions, exclusions and provisional sums before comparing the headline numbers.
A good quote is itemised and covers groundworks, structure, roof, glazing, electrics, plumbing, plastering and the kitchen fit, with VAT stated, clear inclusions and exclusions, provisional sums for undecided items, a staged payment schedule, insurance and a written guarantee, and a realistic programme of usually 10 to 16 weeks.
Rarely. The cheapest quote often leaves out items that reappear as extras, uses lower-spec materials, or comes from a builder without proper insurance or a guarantee. Best value comes from a complete, itemised quote at a fair price, backed by references, insurance and a written workmanship warranty.
A quote is a fixed price the builder commits to for a defined scope, while an estimate is an informed guess that can change. For a kitchen extension always get a written fixed-price quote against agreed drawings and specification, with any provisional sums clearly identified so you know which figures could move.
Avoid large up-front deposits. A reasonable arrangement is a modest deposit to secure the start date, then staged payments against completed milestones such as foundations, structure, watertight and completion. Paying for work as it is done, under a written contract, protects you if anything goes wrong.
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Free, like-for-like quotes from UK extension builders who price the same scope so you compare value with confidence. BestBuilders is free for homeowners with no obligation to accept — you choose who to hire. Ask each firm for proof of public liability insurance and a written price, and check FMB membership on the official FMB register yourself. It pays to price the job first with our kitchen extension cost guide and extension cost calculator.

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