Dunstable, Bedfordshire
Semi-detached rear extension in Dunstable
Semi-detached rear extension in Dunstable: single or two-storey extensions for semi-detached houses, with side access and one party wall. We measure the house, show you what the rules allow, price it in writing and build it.
Dunstable is covered from our Bedfordshire round, including LU6. Semi-detached houses are common across Bedfordshire, and their side access makes rear extensions quicker to build.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Dunstable?
A semi-detached rear extension in Dunstable is priced at £2,010–£3,290 per square metre including VAT as a guide, before kitchen fit-out and fees. East of England prices run slightly above our West Midlands baseline; clay soils near trees are the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £24,000–£39,500 |
| 4 m wide × 5 m deep (20 m²) | £40,500–£65,500 |
| 4 m wide × 6 m deep (24 m²) | £48,500–£79,000 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission for a semi-detached rear extension in Dunstable?
Planning for a semi-detached rear extension in Dunstable follows the English householder rules.
In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Dunstable like to extend?
Post-war semis and newer estates are typical of Dunstable, and many have room for a full-width extension. Shrinkable clay is common in the East of England, so foundations near trees and hedges are designed to NHBC-style depth guidance.
How a semi-detached rear extension in Dunstable comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Semi-detached rear extensions near Dunstable
Close by, we work in Luton, about 4.5 miles away, and Leighton Buzzard, about 6.2 miles away.
- Semi-detached rear extension in Luton
- Semi-detached rear extension in Leighton Buzzard
- Semi-detached rear extension in Flitwick
- Semi-detached rear extension in Harpenden
- Semi-detached rear extension in Tring
Other work in Dunstable:
FAQ
Semi-detached rear extension questions in Dunstable
Is the site visit in Dunstable free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
What postcode areas do you cover around Dunstable?
Including LU6, and the surrounding Bedfordshire area.
What if my neighbour has already extended?
That can make a matching depth easier to justify. We measure theirs at the survey.
Do you handle building control in Dunstable?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Can you match the brick or stone on my Dunstable house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.