What will your project actually cost?
Real 2026 prices including VAT, from the jobs we finished last year. Use the estimator for a range, then book a visit for a fixed, written quote.
Estimated price, including VAT
£57,000 – £69,000
- Weeks on site
- 11 weeks
- Before we start
- Drawings and approvals: 4 to 6 weeks
Approvals you will need
- Permitted development: a lawful development certificate is advised
- Building regulations approval
- Party wall notice if you build on or near the boundary
A guide range from our 2026 prices, not a quote. The fixed written quote follows the free site visit.
Rates behind the estimator
Per square metre of new floor (per metre of span for an opening), plus fixed costs for things like stairs, drainage and steelwork.
| Project | Standard | Mid | Premium | Fixed costs |
|---|---|---|---|---|
| Single-storey extension | £1,900 / m² | £2,300 / m² | £2,850 / m² | £6,500 |
| Double-storey extension | £1,750 / m² | £2,100 / m² | £2,600 / m² | £9,500 |
| Loft conversion | £1,500 / m² | £1,850 / m² | £2,300 / m² | £7,500 |
| Garage conversion | £1,000 / m² | £1,250 / m² | £1,600 / m² | £3,500 |
| Structural opening | £950 / m | £1,150 / m | £1,450 / m | £2,800 |
Three routes to more room
Cost, time and paperwork for the three jobs most people are choosing between.
| Rear extension | Loft conversion | Garage conversion | |
|---|---|---|---|
| Typical cost per m² | £1,900 – £2,850 | £1,500 – £2,300 | £1,000 – £1,600 |
| Typical all-in price | £48,000 – £75,000 | £45,000 – £66,000 | £21,000 – £30,000 |
| Weeks on site | 9 – 14 | 7 – 10 | 4 – 6 |
| Planning | Often permitted development | Rear dormer usually permitted | Usually permitted |
| Building regulations | Yes | Yes, plus fire escape route | Yes |
| Garden lost | Yes, the footprint | None | None (you lose parking) |
| Best for | A bigger kitchen-diner | A bedroom and shower room | A study, playroom or utility |
You never pay ahead of the work
A 10% deposit books your start date. After that, each payment is due only when the work it covers is finished and, where it applies, signed off by building control.
Provisional sums (a drain in the wrong place, a soft spot in a trench) are named and priced in the quote and only charged if they happen. Changes you ask for are priced in writing before we do them.
- Booking the start date10%
- Foundations and drainage signed off20%
- Walls to plate, steels in25%
- Roof on and weathertight20%
- Plastered and first fix complete15%
- Handover and completion certificate10%
Starting prices by service
- Single-storey extensions 9–14 weeks on site From £48,000
- Double-storey extensions 16–24 weeks on site From £92,000
- Loft conversions 7–10 weeks on site From £45,000
- Garage conversions 4–6 weeks on site From £21,000
- Structural openings 1–3 weeks on site From £5,500
- Brick, stone and heritage repair 1–6 weeks on site From £3,500
From first visit to handover
-
Site visit
Within 10 working days
We walk the house with you, measure, check the drains and the loft, and tell you what needs approval. Free, about an hour.
-
Drawings and approvals
4 to 12 weeks
Our designer draws it, the engineer sizes the steels, and we submit planning and building regulations for you.
-
Fixed written quote
5 working days after drawings
Line by line, provisional sums named, a start date and a programme week by week. You sign when you are ready.
-
The build
As programmed
One site manager, a weekly update every Friday, building control booked and met. The site is swept every evening.
-
Handover
Last week on site
A snagging walk-round, the completion certificate, the guarantee in writing and a visit back at six months.
Turn the range into a fixed price
The site visit is free and takes about an hour. We are booking starts from March 2027. Site visits within 10 working days.