The short answer
Getting written quotes from at least three experienced builders is the most important step before committing to any extension project. Quotes based on the same design are the only reliable way to compare cost and scope. Browse our guides on extension costs and choosing a builder to prepare yourself before the quotes come in.
House extensions are one of the most significant investments a homeowner makes, and the quality of the builder you choose — and the clarity of the contract you sign — has a bigger impact on the outcome than almost any other factor. This service connects you with building contractors experienced in domestic house extensions, who can visit your property, review your drawings, and provide written, detailed quotes. There is no cost to you and no obligation to proceed.
Getting extension quotes: what to know
- Cost of using this service Free
- Obligation to proceed? None — quotes are purely informational
- Quotes based on Your site visit and architect’s drawings
- Minimum quotes recommended Three, for comparison
- When to get quotes After planning consent or PD confirmation, with drawings
- What to check in a quote Scope, exclusions, programme, VAT, insurance
When to get extension quotes
The most useful time to get quotes is after your planning position is confirmed and you have a set of drawings. Quotes based on architect’s drawings — where the builder knows exactly what they are building — are far more accurate and comparable than quotes based on a verbal description. If you are still at the “thinking about it” stage, our guides on house extension cost and types of extension can help you form a budget range before commissioning a design.
What to have ready
When you enquire for quotes, having the following ready helps contractors give you a more accurate response:
- Type and size of extension: rear single-storey, side return, double-storey, or a description of what you want to achieve.
- Drawings (if available): planning drawings, building regulations drawings, or even an architect’s concept sketch.
- Planning status: whether planning permission has been granted, whether the works are within permitted development, or whether you are still at the application stage.
- Preferred start date: experienced extension builders are often booked 2–4 months ahead. The earlier you enquire, the more choice you have.
- Broad budget range: this helps contractors identify whether the project is within scope for their business and avoids wasted site visits.
What makes a good quote?
A useful extension quote is more than a single number. It should set out:
- Detailed scope: groundworks, structure, roof, glazing, electrics, plumbing, drainage — each line itemised.
- Exclusions: what is not included (typically kitchen, flooring, decoration, landscaping).
- Programme: the anticipated build duration and proposed start date.
- Payment terms: stage payments tied to the programme, not large upfront sums.
- VAT: clearly stated whether the price is inclusive or exclusive.
- Contract form: a JCT Minor Works or Homeowner Contract, or the builder’s own terms reviewed before signing.
About this service
House Extension Answers is an independent information service. We publish guides and, when asked, connect you with building contractors for your project. We are not a builder and do not carry out works ourselves. We do not guarantee the quality of any contractor introduced through this service — the checks outlined in our guide on how to choose a builder remain your responsibility. When you submit an enquiry, a member of our team will be in touch to discuss your project and connect you with appropriate builders in your area.
This page and the wider House Extension Answers site is general information about the house extension process in England. It is not planning, structural, legal or financial advice. Always obtain independent professional advice for your specific project and verify the credentials of any contractor before signing a contract.
Tell us about your extension project
Fill in a short enquiry and we’ll connect you with experienced extension builders for written quotes. It is free, and there is no obligation to proceed.
Frequently asked questions
Is this service really free?
Yes. There is no charge to use this enquiry service. We are an information publisher; connecting you with builders is a free service we offer alongside our guides.
Do I need drawings before I enquire?
Not necessarily. If you are at the early stages, a description of what you want to achieve is a starting point. However, accurate and comparable quotes require drawings. We can advise on the design process as well as connecting you with builders.
How quickly will I receive quotes?
Typically within a few days of your enquiry, depending on builder availability in your area. Experienced extension builders are often booked ahead, so the earlier you enquire, the more options you will have for your preferred start date.
Are the builders vetted?
We introduce contractors who represent themselves as experienced in domestic house extensions. The due diligence checks recommended in our guide on choosing a builder — references, insurance, contract — remain your responsibility as the client. We are not a builder and do not supervise any works.
Sources & further reading
- Planning Portal — Planning permission and building regulations for house extensions
- LABC — Building regulations process and choosing compliant contractors
- RICS — Guidance on domestic building contracts and professional standards
- FMB (Federation of Master Builders) — Finding a reliable builder and consumer rights guidance
This is general information about house extensions in England and is not planning, structural, legal or financial advice. Costs, timescales and outcomes vary with your design, ground conditions, specification and local authority. Always obtain written quotes and verify planning and building regulations requirements with your local planning authority before committing to any works.