Local costs · South West · September 2026
How much does an extension cost in Bath and North East Somerset?
A mid-range 25 m² single-storey extension in Bath and North East Somerset costs about £66,000 to £81,000 including VAT, or £2,600 to £3,200 per m² at South West prices. Bath and North East Somerset’s own published charge for building control on a 10 to 40 m² extension is £696 (full plans, including VAT): the 14th cheapest of the 91 councils we checked, 17% below the typical council (£840). The council’s published fee list is older or has no date, so check the current fee with the council before you budget. With a measured survey, building regulations drawings, a structural engineer, Bath and North East Somerset’s own building control charge and a 15% contingency, plan for £80,500 to £102,000.
Work out your project in Bath and North East Somerset
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Typical prices in Bath and North East Somerset
| Project | Building work | Budget to plan for |
|---|---|---|
| Single-storey extension, 25 m² | £66,000 to £81,000 | £80,500 to £102,000 |
| Double-storey extension, 40 m² | £95,000 to £120,000 | £114,000 to £148,000 |
| Dormer loft conversion, 30 m² | £49,000 to £60,500 | £60,000 to £77,500 |
| Kitchen, medium | £9,200 to £16,300 | £10,600 to £18,800 |
| Bathroom refit | £6,100 to £9,200 | £7,100 to £10,600 |
Building prices in the South West run about 4% above the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.
Building control fees in Bath and North East Somerset
| Work | Charge |
|---|---|
| Extension up to 10 m² (full plans) | £696 |
| Extension 10 to 40 m² (full plans) | £696 |
| Larger extension, 40 to 60 m² (full plans) | £876 |
| Extension 10 to 40 m² (building notice) | Not published |
| Loft conversion up to 40 m² | £660 |
| Garage conversion | £408 |
Bath and North East Somerset’s own published charge for building control on a 10 to 40 m² extension is £696 (full plans, including VAT): the 14th cheapest of the 91 councils we checked, 17% below the typical council (£840). The council’s published fee list is older or has no date, so check the current fee with the council before you budget. Source: Bath and North East Somerset’s building control charges. The schedule doesn’t give a start date. The charges include VAT.
Check before relying on it: the schedule is older than 2025 or undated, so check it is still current.
Private building control firms (registered building control approvers) set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Bath and North East Somerset compares with every council we checked.
Notes on Bath and North East Somerset’s schedule
Bath and North East Somerset publishes one charge on its own page. It doesn’t say whether a building notice costs the same. The garage figure is for up to 30 m².
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 in writing.
Other councils in the South West
Building control for a 10 to 40 m² extension:
- Bristol: £735
- Wiltshire: £755
- Exeter: £800
- Mid Devon: £896
- North Devon: £896
- Plymouth: £973
- South Hams: £1,095
- Teignbridge: £1,095
- West Devon: £1,095
- Cornwall: £1,140
Questions people ask
How much does an extension cost in Bath and North East Somerset?
A mid-range 25 m² single-storey extension in Bath and North East Somerset costs about £66,000 to £81,000 including VAT for the building work, or £2,600 to £3,200 per m², based on South West prices reviewed in September 2026. With a measured survey, design, a structural engineer, Bath and North East Somerset’s own building control charge and a 15% contingency, plan for £80,500 to £102,000.
How much is building control in Bath and North East Somerset?
Bath and North East Somerset’s own published charge for full plans approval of a 10 to 40 m² extension is £696 (including VAT). The schedule doesn’t give a start date.
How much does a loft conversion cost in Bath and North East Somerset?
A mid-range 30 m² dormer loft conversion in Bath and North East Somerset costs about £49,000 to £60,500 including VAT for the building work, and about £60,000 to £77,500 with fees, Bath and North East Somerset’s own building control charge 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
- When quotes arrive, check each one against the typical range for your area
Work in Bath and North East Somerset? Firm listings on Estiquote’s map of checked local firms open soon: see what you’ll need. Listing will be free while we build the map, with at least 30 days’ notice before any charge.