Two-storey extensions in Buckinghamshire
Two-storey extensions in Buckinghamshire: guide prices for South East England, the rules that apply in England, and the towns we cover.
Buckinghamshire at a glance
- Nation
- England
- Price region
- South East England
- Postcode areas
- HP, MK, SL
- Main town
- Milton Keynes
- Towns listed
- 13
- Site visits
- Free, no obligation
Choose your town
- Milton Keynes
- High Wycombe
- Aylesbury
- Bletchley
- Amersham
- Chesham
- Gerrards Cross
- Chalfont Saint Peter
- Marlow
- Amersham on the Hill
- Newport Pagnell
- Beaconsfield
- Buckingham
Guide prices in South East England
| Extension type | Per m² | Typical project |
|---|---|---|
| Two-storey rear extension | £2,200–£2,970 per m² | £61,500–£83,000 |
| Two-storey side extension | £2,260–£3,030 per m² | £94,500–£127,000 |
| Two-storey wraparound extension | £2,360–£3,250 per m² | £132,500–£181,500 |
| Part single, part two-storey | £2,200–£3,030 per m² | £79,000–£109,000 |
| Extension over a garage | £1,930–£2,800 per m² | £34,500–£50,500 |
| First-floor extension over an existing single storey | £1,980–£2,860 per m² | £27,500–£40,000 |
| Two-storey front extension | £2,420–£3,300 per m² | £29,000–£39,500 |
Including VAT, Standard spec. See all prices and fees.
Across Buckinghamshire we cover Milton Keynes (MK5), High Wycombe (HP11), Aylesbury (HP17), Bletchley (MK1), Amersham (HP7), Chesham (HP5), Gerrards Cross (SL9) and Chalfont Saint Peter (HP8), plus the smaller places around them.
Which type suits your house?
Rear, side, wraparound or over the garage: each adds space in a different way. For most houses in Buckinghamshire, one or two of these will clearly suit the plot better than the rest, and we'll tell you which.
The rules in England
Buckinghamshire is in England. Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
The full England rules explained
Extension types
- Two-storey rear extensions
- Two-storey side extensions
- Two-storey wraparound extensions
- Part single, part two-storey extensions
- Extensions over a garage
- First-floor extensions
- Two-storey front extensions
By house type
- Two-storey extensions for semi-detached houses
- Two-storey extensions for detached houses
- Two-storey extensions for end-of-terrace houses
Rooms and uses
- Kitchen extensions with bedrooms above
- Extra bedroom and en-suite extensions
- Two-storey annexe extensions
- Garage conversions with a room above
Design and approvals
- Two-storey extension plans and drawings
- Planning permission for two-storey extensions
- Structural engineering for two-storey extensions
- Building regulations for two-storey extensions
- Party wall notices for extensions
- Design and build two-storey extensions
Questions about extensions in Buckinghamshire
How much does a two-storey extension cost in Buckinghamshire?
In South East England our guide for a two-storey rear extension is £2,200–£2,970 per m² including VAT, about £61,500–£83,000 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Side and wraparound extensions cost a little more per m².
Do I need planning permission in Buckinghamshire?
Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026).
Do you cover the whole of Buckinghamshire?
Yes. We list the main towns here, but we cover the whole of Buckinghamshire including villages. The first site visit is free.
What happens at the first visit?
We look at your house, the boundaries, access and drains, talk through what you need and explain the approvals. Then we price the design stage, including the measured survey, in writing.