Two-storey extensions in West Sussex
Whether you're in the biggest town in West Sussex or a village outside it, we can design, get approval for and build your extension.
West Sussex at a glance
- Nation
- England
- Price region
- South East England
- Postcode areas
- BN, PO, RH
- Main town
- Crawley
- Towns listed
- 19
- Site visits
- Free, no obligation
Choose your town
- Crawley
- Worthing
- Bognor Regis
- Littlehampton
- Horsham
- Haywards Heath
- Chichester
- Burgess Hill
- East Grinstead
- Shoreham-by-Sea
- Emsworth
- Lancing
- Rustington
- Broadfield
- Hurstpierpoint
- Barnham
- Selsey
- Westergate
- Steyning
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.
West Sussex towns we list: Crawley (RH10), Worthing (BN11), Bognor Regis (PO21), Littlehampton (BN17), Horsham (RH12), Haywards Heath (RH16), Chichester (PO18) and Burgess Hill (RH15). Every other address in West Sussex is covered as well.
Which type suits your house?
Which type suits your house in West Sussex depends mostly on where you have room. A deep garden points to a rear extension; space beside the house points to a side or over-garage extension; a house that already has a single-storey extension can often take a first floor on top.
The rules in England
West Sussex 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 West Sussex
How much does a two-storey extension cost in West Sussex?
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 West Sussex?
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 West Sussex?
Yes. We list the main towns here, but we cover the whole of West Sussex 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.