Compare Builders: How to Vet Extension Quotes in 2026
The cheapest quote is rarely the best one. To compare builders properly you need to price the same scope with each, read the quotes line by line, and check credentials, references and the contract before any money changes hands. Get at least 3 quotes and you will quickly see the market rate and spot the outliers. This 2026 guide shows exactly how to vet a quote, what a good one includes, and the red flags that should make you pause.
What a Good Builder Quote Includes
A proper quote is itemised, not a single bottom-line number. Use this checklist to judge whether each quote gives you enough to compare fairly and to hold the builder to.
If a quote is a single figure with no breakdown, ask for it in writing and itemised before you compare it with the others.
What to Trust and What to Question
✓ Good signs
- An itemised written quote
- Public liability insurance and references
- A stage payment schedule, modest deposit
- Membership of a trade body such as the FMB
- Happy to show completed work
✗ Red flags
- A large upfront deposit demand
- Cash only with no paperwork
- A price far below the others
- No written contract offered
- Pressure to start immediately
How to Compare Quotes Fairly
The most common mistake is comparing quotes on the bottom-line total. The cheapest figure is often the one that has left items out, so a like-for-like comparison only works when every builder has priced the same written scope and drawings. Hand each of them the identical brief, then read the quotes side by side, item by item.
Look closely at exclusions and provisional sums. A quote that looks GBP 5,000 cheaper may simply have excluded the foundations or the finishes that the others included. Once the scope matches, the right choice is the builder who scoped the job most thoroughly and prices it fairly, not the lowest number on the page.
Comparing Builder Quotes FAQs · 2026
Compare Builder Quotes
Free quotes from UK builders, priced on the same scope so you can compare them 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 trade-body membership on the official FMB register yourself. It pays to price the job first with our extension cost guide and extension specialists.
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