Double-storey extensions for homes in Aylesbury
Planning a double-storey extension in Aylesbury? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in AylesburyFrom £42,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsHP17, HP19, HP20, HP21, HP22
Double-storey extension prices in Aylesbury
Labour and material costs vary across the UK, so for Aylesbury we use our South East England factor (×1.12). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Aylesbury: £1,740 to £3,360 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £42,500 – £51,000 | £48,000 – £63,500 | £61,500 – £81,000 |
| 4 m × 4 m, two floors 32 m² | £55,500 – £66,500 | £64,500 – £84,500 | £82,000 – £108,000 |
| 4 m × 6 m, two floors 48 m² | £83,000 – £99,500 | £96,500 – £126,500 | £123,500 – £161,500 |
Try the guide-price tool to see a range for your own size and finish.
Local to Aylesbury
Site visits are available across Aylesbury (HP17, HP19, HP20, HP21, HP22). The same team covers Chesham (12 miles), Bletchley (13 miles), High Wycombe (13 miles), Amersham (13 miles), all within easy reach.
Thame, in Oxfordshire, is roughly 9 miles from Aylesbury and also on our list. Homes across the South East range from Victorian terraces in the older town centres to large detached houses on the edges, so the right extension type varies street by street.
Do I need planning permission in Aylesbury?
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
Applications are decided by the local planning authority (your district, borough or unitary council).
Included in a typical project
- Householder planning application where needed
- Insulation, plastering, electrics and plumbing to finish
- Foundations sized for two floors
- Building regulations drawings and structural design
- Ground and first floor structure, roof tied into the existing roof
- Measured survey, design and planning drawings
The roof is what makes a two-storey extension look right or wrong. We match the pitch and materials of the main house wherever possible and plan the upstairs layout around the existing landing so the new rooms feel original rather than bolted on.
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Common questions in Aylesbury
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Aylesbury, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How long does a double-storey extension take to build in Aylesbury?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 8–16 weeks design and approvals.
Will my neighbours in Aylesbury be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £1,740 to £3,360 per m² of new floor area including VAT, compared with £1,960 to £3,810 per m² for single-storey work, because the foundations and roof are shared across two floors.
Does a double-storey extension need planning permission?
Often, yes. In England a two-storey rear extension can be permitted development only if it projects no more than 3 m and sits at least 7 m from the rear boundary, with matching roof pitch and obscure side windows. Side extensions over one storey always need planning permission. We confirm the route at the survey.
Book a free site visit in Aylesbury
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.