A builder's quote can look simple, a single number at the bottom of a page, but what sits behind that number is what decides whether your project runs smoothly. Two quotes for the same job can differ by thousands of pounds because they include different things. This guide is general UK advice on how to read a quote and contract, what to look out for, and which questions to ask before you sign. It isn't legal advice, and it doesn't describe any particular company's terms.
Quote, estimate or contract?
These words are often mixed up, but they mean different things:
An estimate is a rough guide to likely cost and isn't usually binding.
A quote is a fixed price for a defined scope of work, usually valid for a set period.
A contract is the signed agreement that sets out the work, price, payments, timetable and responsibilities. Once you sign it, it's what both sides rely on.
For anything beyond small jobs, get a written contract that refers to the quote and drawings. Standard contracts designed for homeowners, such as those published by JCT, are available and can be a useful starting point. Ask a solicitor if you're unsure.
Scope of work and specification
Most disputes come from a mismatch about what's included. A good quote or specification should say clearly:
What work is being done, room by room or stage by stage, with reference to drawings.
The materials and products to be used, or the budget for them.
What isn't included, such as decorating, flooring, landscaping, kitchens or scaffolding.
Who is responsible for planning, Building Control and any required surveys, engineer's calculations or party wall notices.
How waste, skips, welfare facilities and site clean-up are handled.
Vague wording such as "supply and fit kitchen" or "make good" leaves room for argument. If something matters to you, check it's written down. Our guide to how the building process works shows the stages a project typically goes through.
Provisional sums and prime cost sums
Not everything can be priced exactly before work starts, so quotes often include allowances:
Provisional sums are placeholders for work that can't be fully defined yet, such as ground conditions or hidden structure. The final cost may be higher or lower.
Prime cost (PC) sums are allowances for items you'll choose later, such as tiles, sanitaryware or a kitchen.
These are legitimate, but they should be clearly marked and reasonable. A quote with lots of large provisional sums isn't really a fixed price. Ask what each one covers, what happens if the actual cost is higher, and how any saving will be passed to you. When comparing quotes, add up the provisional and PC sums separately so you compare like for like.
Payment schedules and deposits
How and when you pay is as important as how much. As a general guide:
Payments should be linked to clear stages of completed work, such as foundations, walls, roof, first fix, second fix and completion.
Be cautious about large payments upfront. A small deposit to secure materials or a start date can be reasonable, but you should understand what it covers, and it should be written down.
Never pay ahead of the work. Paying for stages once they're done keeps your risk low.
Consider keeping back a small retention, for example a percentage for a fixed period after completion, to cover snagging and defects.
Keep records of every payment and avoid paying in cash without a receipt.
If you're borrowing money for the work, check how your lender releases funds, as this may affect the payment schedule.
Variations and extras
Changes happen on almost every project, whether you change your mind or something unexpected is found. What matters is how they're handled. A good contract says that:
Changes are agreed in writing before the work is done.
The cost and any effect on the programme are stated clearly.
Both parties sign or confirm the variation.
Ask how day rates or additional costs will be calculated, and how hidden problems, such as poor ground or rot, will be dealt with. Our guide to working with a project manager and quantity surveyor explains how costs can be tracked as a project develops.
Insurance, guarantees and paperwork
Before you sign, ask to see:
Public liability insurance, which covers damage to property or injury to others.
Employer's liability insurance, which is a legal requirement if the builder employs staff.
Contract works insurance or details of who insures the work in progress. You should also tell your own home insurer about the project.
Any guarantee or warranty offered for the work, including how long it lasts and what it covers.
Planning permission and Building Regulations responsibilities, including who applies for what and who arranges inspections.
If you're also affected by shared walls or boundaries, see our Party Wall Act guide. Our Building Regulations guide explains how inspections generally work.
Timetable, delays and red flags
A contract should give a start date, a realistic programme and an expected completion date, along with what happens if things slip, for example because of weather, supply issues or variations. Be wary if you see:
Pressure to sign or pay quickly.
A quote with no address, no written terms, or no clear description of the work.
A price that's much lower than others without a clear reason.
Requests for large upfront sums or cash payments.
Reluctance to provide insurance details or references.
Because the rules about cancelling contracts signed at your home can vary, check your rights and read the paperwork carefully before you commit. If you're also weighing up how to pick a contractor, our guide to finding trusted builders in Cornwall is a good companion to this one.
Builder's quote FAQs
How many quotes should I get?
Three is a common starting point, but the key is that each is based on the same drawings and specification so they can be compared fairly.
Is the cheapest quote the best?
Not necessarily. A low price can mean something is left out, so compare scope, provisional sums and payment terms as well as the total.
What deposit is reasonable?
There's no single rule. As a general principle, avoid large upfront payments, and link payments to completed stages wherever possible.
Can a quote change after I accept it?
A fixed-price quote shouldn't change unless the scope changes through a written variation, or a provisional sum is adjusted according to the contract.
Talk to us about your project
If you'd like to discuss a home extension, renovation or new build, call Cornish Building Company on 01208 816991 or contact us. It also helps to look at our home extensions and property renovation pages before you get in touch.
