New · Know what your build should cost
Upload the plans for your extension or loft conversion and get a trade-by-trade labour and materials estimate from a Cambridgeshire builder. Use it to plan your budget and to check the quotes you get.
Priced from our own real estimates, not national averages: over 20 recent extension and loft jobs and more than 5,500 individually priced items, backed by years of building experience, and fine-tuned for building costs where you live.
Both are estimates based on your drawings, not quotes or fixed prices. If you go ahead with Howell & Sons, we deduct the fee from your build.
How it works
Example
A made-up example: a 5.6 m × 4.0 m single-storey rear extension with bi-fold doors and a roof lantern. These are our own sample drawings, not a real client's.
What you get back
A labour and materials breakdown for every trade (groundworks, brickwork, roof, windows and doors, joinery, plastering, electrics, plumbing, decorating), plus contingency, preliminaries and a price range.
Order
Online ordering opens soon. In the meantime, email your drawings to info@howellandsons.co.uk or call 01223 501605.
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Questions
We tested our pricing against our own past estimates. For typical extensions the instant price was usually within about 10%, but it can be out by 20% or more on some jobs, which is why we quote ±20% for instant estimates. When Paul reviews an estimate he checks the measurements and prices, so reviewed estimates should be within about ±10% once the details are confirmed. Lofts, garages and unusual projects vary more.
For an extension, loft or garage conversion: existing floor plans and elevations, and proposed floor plans and elevations. Your architect's survey drawings are fine for the existing. For a new garage or outbuilding: proposed floor plans and elevations, plus sections and a site plan if you have them. The structural engineer's calculations help too.
If we can see your project doesn't suit instant pricing (for example it's very small or unlike the jobs we've priced before), Paul will check it by hand at no extra cost. It will then take up to 3 working days.
No. It's an estimate from your drawings. A fixed quote needs a site visit, final structural details and your choice of finishes. If you'd like a quote from us, get in touch; if you go ahead with Howell & Sons, we deduct the estimate fee from your build.
Architect's, engineer's, planning, building control and party wall fees; kitchens, bathrooms and fitted furniture; floor finishes; and anything shown under "no allowance for" on your estimate. Your estimate lists the assumptions we've made.
From the labour and materials costs in our own recent estimates for extensions and loft conversions in Cambridgeshire (over 20 jobs and more than 5,500 priced items), brought up to today's prices. If your project is outside the East of England, we adjust the prices using the building industry's regional cost figures (BCIS), so they're as close to local rates as we can make them. See how costs vary across the UK. For typical figures, see how much an extension costs in Cambridgeshire.
Terms
Plain-English terms for our instant and reviewed estimates. If anything's unclear, call us on 01223 501605 before you order.
These terms apply when you order an instant or reviewed estimate from Howell & Sons Construction Ltd ("we", "us"), a company registered in England and Wales, company number 11270942, registered office The Barn, Musgrave Farm, Horningsea Road, Fen Ditton, Cambridge CB5 8SZ. You can contact us on 01223 501605 or at info@howellandsons.co.uk.
An estimate of the building cost of your project, worked out from the drawings and information you send us. It's a guide to help you budget and compare quotes. It is not a quote, a fixed price or an offer to carry out the work.
Work to an existing house (extensions, loft and garage conversions): existing floor plans, existing elevations, proposed floor plans and proposed elevations. We need the existing drawings to see what's being altered; architect's survey drawings are fine. A new building (garages and outbuildings): proposed floor plans and elevations, plus sections and a site plan where they've been drawn. Structural engineer's details and specification notes help where you have them.
If your drawings don't show enough to measure the work reasonably, we may ask you for more information, make standard assumptions for a typical domestic build (which we'll list on your estimate), or decline the order and refund you in full. Waiting for information can delay your estimate. If your drawings and your notes disagree, we follow the drawings unless your notes say otherwise.
Our prices are for typical domestic projects: an extension, a loft or garage conversion, or a new garage or outbuilding. If your drawings show a much larger or more complex project, such as several extensions or a whole-house renovation, we'll contact you before going further. If you'd rather not continue, we'll refund you in full.
Instant estimates are worked out automatically and aren't checked by a person, so they can be inaccurate. Treat them as a guide within about ±20%; it can be wider for unusual projects. Reviewed estimates are checked by us; treat them as a guide within about ±10%. If an instant order looks unsuited to automatic pricing, we may check it by hand at no extra cost.
Architect's, engineer's, planning, building control and party wall fees; kitchens, bathrooms and fitted furniture; floor finishes; and anything listed under "no allowance for" on your estimate. Prices are based on our costs in Cambridgeshire.
Instant estimates are usually ready within minutes. Reviewed estimates, and instant orders we check by hand, are usually ready within 3 working days (Monday to Friday, not bank holidays) of receiving your payment and all the drawings we need.
An instant estimate costs £59.95 and a reviewed estimate £99.95, including VAT. You pay by card through Stripe when you order.
Please check your estimate within 5 working days of receiving it and tell us about anything that looks wrong or missing. We'll correct any mistakes of ours free of charge. For reviewed estimates we'll also make reasonable changes free of charge, as long as the size and scope of the project stay the same.
When you order, you ask us to start straight away, so you lose your right to cancel once your estimate has been delivered. If we can't produce an estimate from your drawings, or you choose not to continue after we contact you about a larger project, we'll refund you in full.
If you go ahead with Howell & Sons for the work, we deduct the estimate fee from the price of your build.
We use your drawings and details to prepare your estimate and to answer any questions about it. We may use the measurements and prices, without your name or address, to improve our pricing. We only share your drawings with the services that help us produce your estimate, such as the AI service that reads the measurements. See our privacy policy.
We prepare every estimate with reasonable care and skill. An estimate is a guide, not a guarantee of what your build will cost, so please don't rely on it as one. If we're at fault, our liability to you is limited to the fee you paid, except where the law doesn't allow it to be limited, including for death or personal injury caused by negligence, or for fraud. Nothing in these terms affects your legal rights as a consumer.
These terms are governed by the law of England and Wales, and the courts of England and Wales can deal with any dispute. If you live in Scotland or Northern Ireland, you can also bring a claim in your local courts.
