How to get an accurate quote from a builder in London

The more precisely you describe the job, the more accurate the quote will be. Give every builder the same written brief, drawings and specification, ask for an itemised quote with a fixed price rather than an estimate, check what is excluded, and agree how changes and payments will work in writing before anything starts. Then you can compare quotes like for like instead of guessing why one price is higher than another.

By Przemyslaw Smolarczyk Published 10 November 2026 6 minutes read

Builder marking a length of timber with a pencil before cutting

Key facts

A quote is a price for the work described; an estimate is a rough figure that can change.

If no price is agreed in a contract for a service, the law says you pay a reasonable price, which is easy to dispute.

A skip on a public road needs a council permit; in most areas the skip company arranges it.

Work on a shared wall or near a neighbour's foundations needs party wall notice before it starts.

A contract agreed in your home normally gives you 14 days to cancel.

What is the difference between a quote and an estimate?

A quote is a price for the specific work described in it, which should not go up unless you agree to a change. An estimate is a builder's best guess at the cost, and the final bill can be higher. Trading standards advice is to ask for a quote, in writing, that lists what is included. If a contract for a service does not fix the price at all, the Consumer Rights Act 2015 says you must pay a reasonable price, which leaves plenty of room for disagreement.

What should you prepare before asking for quotes?

Prepare a short written brief that every builder receives in the same form. The better the brief, the closer the quotes will be to the final cost. It should include:

The scope: what you want done, room by room, and what you do not want touched.
Drawings: plans from an architect or designer, and structural calculations if walls or beams are involved.
A specification: the finishes, fittings and appliances you have in mind, and who supplies each item.
Approvals: whether planning permission, building regulations approval or party wall notices are needed, and who is arranging them.
Practical details: access to the property, parking on your street, whether you will live in the house during the work and when you would like to start.
Photos and measurements of the areas involved.

Ask each builder to visit before pricing. A quote given without seeing the property has to rely on assumptions, and assumptions are where extra costs come from.

Why do quotes for the same job differ so much?

Quotes usually differ because builders have assumed different things, not only because they charge different rates. One may have priced mid-range tiles and another basic ones; one may include removing waste and another may leave it out. Ask every builder to itemise the quote, and compare it line by line against your brief.

Look out for two kinds of allowance. A provisional sum is an amount set aside for work that cannot be defined yet, such as foundations whose depth is only known once digging starts. A prime cost sum is an allowance for items you have not chosen yet, such as a kitchen or sanitaryware. Both are reasonable, but they are not fixed prices: if two quotes use very different allowances, the totals are not comparable.

Which London costs should a quote include?

Building in London brings costs that are easy to miss, so ask each builder whether they are included:

Skips: a skip on a public road needs a permit from the council. In most areas the skip hire company gets it, but in some you have to apply yourself.
Parking: many London streets need a council permit or a suspended bay for vans and deliveries.
Scaffolding: scaffolding on the pavement usually needs a licence from the council.
Waste: removal and disposal of rubble and old fittings.
Approvals and fees: building control fees, and party wall surveyor fees if your neighbours dissent.
VAT: whether the price includes VAT.

What should the written agreement cover?

Before work starts, put the agreement in writing. It should state the scope and the price, a payment schedule, the expected start and finish dates, who is responsible for approvals, what happens if unexpected problems are found and how changes are agreed. Any change to the work, and its price, should be agreed in writing before it is carried out.

The law gives you some protection whatever the contract says. Under the Consumer Rights Act 2015, a trader must carry out a service with reasonable care and skill. If you agree the contract in your home rather than at the builder's premises, the Consumer Contracts Regulations normally give you 14 days to cancel, and the builder should tell you about this right in writing.

What payment schedule is reasonable?

A fair schedule links payments to work that has been completed, so you never pay far ahead of progress. Trading standards advice is to avoid paying the full price up front. Agree the stages, such as foundations, structure, first fix and completion, and the amount for each, before work begins.

How should you compare quotes from different builders?

Compare what each quote includes before you compare the totals. Check that every builder has priced the same scope and specification, look at the provisional sums and exclusions, and ask about anything unclear. Ask about insurance, guarantees on the work, who will be on site day to day and how long the job is expected to take. The lowest total is not necessarily the cheapest outcome if it leaves out things another quote includes.

Frequently asked questions

How many quotes should I get?

Council trading standards guides commonly suggest getting at least three written quotes, based on the same brief, so you can see what a fair price looks like.

Can a builder charge more than the quote?

Not for the work described in the quote, unless you agree. Extra work, changes you ask for and problems that could not be seen at the start are normally priced separately, which is why the agreement should say how such changes are agreed.

Do I need drawings before asking for a quote?

For extensions, loft conversions and structural changes, yes: without drawings each builder prices a different idea of the job. For simpler work, such as decorating or flooring, a clear written description, measurements and photos are usually enough.

Who arranges party wall notices?

The homeowner is responsible for giving notice to the neighbours, although a surveyor can do it for you. Notice must be given between 2 months and a year before the work starts.

How can GONT LTD help with your quote?

GONT LTD is a London building company offering a full range of building services, from extensions and loft conversions to plumbing, electrical work and decorating. Every project starts with a free consultation and a free quote. Call +44 7783 930505 (Monday to Friday, 9am to 5pm), email info@gont.co.uk, visit our showroom at 9 Royal Parade, Dawes Road, Fulham, or describe your project on our contact page.

Sources

General guidance for homeowners in England, based on the sources above. It is not legal advice.