How to compare builder quotes

The short answer

You can only compare builder quotes properly when they price the same defined work. Start by checking scope and exclusions, then look at provisional sums, programme, payment expectations, VAT treatment and qualifications, and only then compare totals. The lowest figure is often the one with the most left out.

Key points

Like-for-like comparison requires a common scope, ideally a written specification issued to everyone.
Exclusions and provisional sums explain most of the gap between quotations.
Check whether VAT is included, excluded or not chargeable.
A short programme with no detail can be a risk, not a benefit.
Payment terms tell you as much about a builder as their price.

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Worked example: compare the total for the same work

Illustrative figures only, not typical building prices: Builder A quotes £48,000 but excludes £4,000 of flooring and £2,000 of waste removal. Builder B quotes £52,000 including both. If scope and VAT treatment are otherwise identical, A totals £54,000 for comparison and B totals £52,000. Ask for confirmed missing prices rather than assuming an allowance will be enough.

Use one row per work item and one column per builder.
Record included, excluded, provisional or unclear against each item.
Show VAT and client-supplied items separately.
Ask for revised written quotations before choosing a builder.

Compare like for like

If each builder priced their own interpretation of your project, the differences you see are differences in assumption, not value. Issuing one written scope to everyone is the single most effective step you can take.

Where quotes were returned against different scopes, rebuild them onto a common list of items before drawing any conclusion.

Check the exclusions

Read the exclusions before the total. Common exclusions include fees and surveys, structural design, scaffolding, waste removal, making good and decoration, kitchen and sanitary appliances, and anything relating to unknown ground conditions.

For each exclusion, ask who is paying and when that cost will land.

Provisional amounts and allowances

Provisional sums are placeholders for work not yet defined. They are legitimate, but a quotation with large provisional sums is a partial price. Confirm what each provisional item covers, how it will be valued when it is fixed, and whether the builder's overhead applies on top.

Programme

Ask for a start date, a duration and the key stages. Check that the programme allows for lead times on windows, steel and joinery, for statutory inspections, and for any notice periods such as party wall procedures. An optimistic programme usually resurfaces as pressure later.

Payment expectations

Look at how much is requested up front, how payments are staged, and what evidence triggers each one. Payments tied to identifiable completed stages are easier to manage than payments tied to dates alone.

VAT

Confirm whether the figure includes VAT, excludes VAT, or whether the builder is not VAT registered. This alone can explain a large apparent difference between two quotations. Certain works have different VAT treatment; check the current position on GOV.UK or with an accountant rather than assuming.

Qualifications, insurance and references

Public liability insurance, and contractors' all risks cover where relevant.
Registration with a competent person scheme for electrical, gas or heating work.
Named subcontractors for specialist trades.
Recent, relevant references you actually follow up.
Written confirmation of who is supervising the site day to day.

Do not simply take the lowest figure

A lower price can reflect different assumptions, exclusions, efficiency or a different approach. Ask for an explanation and compare the written scope before treating the difference as a saving.

Things to check

Did every builder price the same written scope?
What is excluded from each quotation, and who carries that cost?
How large are the provisional sums, and how will they be valued?
Is VAT included, excluded, or not applicable?
Are payment stages tied to identifiable progress?
Is the programme realistic once lead times and inspections are allowed for?
Have insurance and scheme registrations been evidenced in writing?

Give every builder the same information

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Important

This guide is general information for UK homeowners. It is not legal, planning, structural or professional advice, and it does not take account of your individual circumstances. Rules change and vary between England, Wales, Scotland and Northern Ireland, and by local authority.

KEZARIQ provides guidance and documents you complete and review yourself. It does not manage your project, carry out professional services, or replace an architect, surveyor, structural engineer, planning consultant or other competent professional where one is required. Nothing here guarantees planning permission, Building Regulations approval, prices, contractor performance or any project outcome. You remain responsible for your own project and decisions.