Local costs · South East · September 2026
How much does an extension cost in Oxford?
A mid-range 25 m² single-storey extension in Oxford costs about £72,500 to £89,500 including VAT, or £2,900 to £3,600 per m² at South East prices. Oxford charges £1,125 for building control on a 10 to 40 m² extension (full plans, including VAT): the 8th dearest of the 91 councils we checked, 34% above the typical council (£840). With design, a structural engineer, building control and a 15% contingency, budget £89,500 to £115,000.
Work out your project in Oxford
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Typical prices in Oxford
| Project | Building work | Budget to plan for |
|---|---|---|
| Single-storey extension, 25 m² | £72,500 to £89,500 | £89,500 to £115,000 |
| Double-storey extension, 40 m² | £105,000 to £132,000 | £128,000 to £167,000 |
| Dormer loft conversion, 30 m² | £65,000 to £80,000 | £80,500 to £102,000 |
| Kitchen, medium | £9,700 to £17,200 | £11,100 to £19,800 |
| Bathroom refit | £6,500 to £9,800 | £7,500 to £11,300 |
Building prices in South East run about 15% above the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.
Building control fees in Oxford
| Work | Charge |
|---|---|
| Extension up to 10 m² (full plans) | £925 |
| Extension 10 to 40 m² (full plans) | £1,125 |
| Larger extension, 40-60 m² (full plans) | £1,255 |
| Extension 10 to 40 m² (building notice) | £1,125 |
| Loft conversion up to 40 m² | £1,190 |
| Garage conversion | £860 |
Oxford charges £1,125 for building control on a 10 to 40 m² extension (full plans, including VAT): the 8th dearest of the 91 councils we checked, 34% above the typical council (£840). Source: Oxford's building control charges, 1 April 2026. Inc VAT column.
Private approved inspectors set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Oxford compares with every council we checked.
Notes on Oxford's schedule
Own schedule. Single charge, same for full plans and building notice. Garage conversion figure is the <=40 m2 band.
Planning
If your extension needs planning permission, a householder application in England costs £548. Many single-storey rear extensions are permitted development and need no application, and a lawful development certificate (£274) confirms it.
Other councils in South East
Building control for a 10 to 40 m² extension:
- Milton Keynes: £840
- Horsham: £858
- Crawley: £858
- Folkestone and Hythe: £942
- Hart: £960
- Rushmoor: £960
- Windsor and Maidenhead: £990
- Maidstone: £1,023
- West Berkshire: £1,055
- Wokingham: £1,055
- Winchester: £1,085
- Runnymede: £1,182
- Waverley: £1,280
Questions people ask
How much does an extension cost in Oxford?
A mid-range 25 m² single-storey extension in Oxford costs about £72,500 to £89,500 including VAT for the building work, or £2,900 to £3,600 per m², based on South East prices reviewed in September 2026. With fees and a 15% contingency, budget £89,500 to £115,000.
How much is building control in Oxford?
Oxford charges £1,125 (including VAT) for a 10 to 40 m² extension (full plans), according to its published schedule (1 April 2026).
How much does a loft conversion cost in Oxford?
A mid-range 30 m² dormer loft conversion in Oxford costs about £65,000 to £80,000 including VAT for the building work, and about £80,500 to £102,000 with fees and a 15% contingency.
Before you get quotes
- How to compare builders' quotes line by line
- Plan your whole budget, including the costs people forget
- Trades: price an extension element by element with editable unit rates