Local costs · North East · September 2026
How much does an extension cost in Northumberland?
A mid-range 25 m² single-storey extension in Northumberland costs about £56,000 to £68,500 including VAT, or £2,200 to £2,700 per m² at North East prices. Northumberland’s own published charge for building control on a 10 to 40 m² extension is £780 (full plans, including VAT): 7% below the typical council (£840). With a measured survey, building regulations drawings, a structural engineer, Northumberland’s own building control charge and a 15% contingency, plan for £68,500 to £87,000.
Work out your project in Northumberland
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Typical prices in Northumberland
| Project | Building work | Budget to plan for |
|---|---|---|
| Single-storey extension, 25 m² | £56,000 to £68,500 | £68,500 to £87,000 |
| Double-storey extension, 40 m² | £80,500 to £101,000 | £97,000 to £126,000 |
| Dormer loft conversion, 30 m² | £41,500 to £51,000 | £51,000 to £66,500 |
| Kitchen, medium | £8,500 to £15,000 | £9,700 to £17,300 |
| Bathroom refit | £5,600 to £8,400 | £6,400 to £9,600 |
Building prices in the North East run about 12% below the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.
Building control fees in Northumberland
| Work | Charge |
|---|---|
| Extension up to 10 m² (full plans) | £780 |
| Extension 10 to 40 m² (full plans) | £780 |
| Larger extension, 30 to 50 m² (full plans) | £960 |
| Extension 10 to 40 m² (building notice) | £780 |
| Loft conversion up to 40 m² | Not published |
| Garage conversion | £660 |
Northumberland’s own published charge for building control on a 10 to 40 m² extension is £780 (full plans, including VAT): 7% below the typical council (£840). Source: Northumberland’s building control charges. Schedule date: Scheme of charges November 2025. The charges include VAT.
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 Northumberland compares with every council we checked.
Notes on Northumberland’s schedule
Northumberland publishes its own scheme, with one charge that includes the inspections and is the same for a building notice. Extensions, lofts and garage conversions share two bands, under 30 m² and 30 to 50 m², so the 10 to 40 m² figure is the under 30 m² charge; 30 to 50 m² costs £960. We left the loft figure out because a 40 m² loft falls across both bands.
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 North East
Building control for a 10 to 40 m² extension:
- Stockton-on-Tees: £697
- Darlington: £710
- Durham: £743
- Sunderland: £840
- Newcastle upon Tyne: £918
- Gateshead: £965.34
- South Tyneside: £970
Questions people ask
How much does an extension cost in Northumberland?
A mid-range 25 m² single-storey extension in Northumberland costs about £56,000 to £68,500 including VAT for the building work, or £2,200 to £2,700 per m², based on North East prices reviewed in September 2026. With a measured survey, design, a structural engineer, Northumberland’s own building control charge and a 15% contingency, plan for £68,500 to £87,000.
How much is building control in Northumberland?
Northumberland’s own published charge for full plans approval of a 10 to 40 m² extension is £780 (including VAT). Schedule date: Scheme of charges November 2025.
How much does a loft conversion cost in Northumberland?
A mid-range 30 m² dormer loft conversion in Northumberland costs about £41,500 to £51,000 including VAT for the building work, and about £51,000 to £66,500 with fees, Northumberland’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 Northumberland? 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.