Local costs · South West · September 2026
How much does an extension cost in Plymouth?
A mid-range 25 m² single-storey extension in Plymouth costs about £65,500 to £81,000 including VAT, or £2,600 to £3,200 per m² at South West prices. Plymouth charges £973 for building control on a 10 to 40 m² extension (full plans, including VAT): 16% above the typical council (£840), though its published schedule is older or undated. With design, a structural engineer, building control and a 15% contingency, budget £81,500 to £105,000.
Work out your project in Plymouth
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Typical prices in Plymouth
| Project | Building work | Budget to plan for |
|---|---|---|
| Single-storey extension, 25 m² | £65,500 to £81,000 | £81,500 to £105,000 |
| Double-storey extension, 40 m² | £95,000 to £120,000 | £116,000 to £152,000 |
| Dormer loft conversion, 30 m² | £58,500 to £72,500 | £73,000 to £93,000 |
| 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 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 Plymouth
| Work | Charge |
|---|---|
| Extension up to 10 m² (full plans) | £582 |
| Extension 10 to 40 m² (full plans) | £973 |
| Larger extension, 40-100 m² (full plans) | £1,101 |
| Extension 10 to 40 m² (building notice) | £1,203 |
| Loft conversion up to 40 m² | £882 |
| Garage conversion | £587 |
Plymouth charges £973 for building control on a 10 to 40 m² extension (full plans, including VAT): 16% above the typical council (£840), though its published schedule is older or undated. Source: Plymouth's building control charges, Not stated ("Changes to fees are updated every April"). Full-plan column headed "inc VAT"; inspection column VAT status not labelled.
Check before relying on it: the schedule is older than 2025 or undated, so check it is still current.
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 Plymouth compares with every council we checked.
Notes on Plymouth's schedule
Own page. Bands <=15 / 15-40 / 40-100 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.
Other councils in South West
Building control for a 10 to 40 m² extension:
- Bath and North East Somerset: £696
- Bristol: £735
- Wiltshire: £755
- Exeter: £800
- Mid Devon: £896
- North Devon: £896
- South Hams: £1,095
- Teignbridge: £1,095
- West Devon: £1,095
- Cornwall: £1,140
Questions people ask
How much does an extension cost in Plymouth?
A mid-range 25 m² single-storey extension in Plymouth costs about £65,500 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 fees and a 15% contingency, budget £81,500 to £105,000.
How much is building control in Plymouth?
Plymouth charges £973 (including VAT) for a 10 to 40 m² extension (full plans), according to its published schedule (Not stated ("Changes to fees are updated every April")).
How much does a loft conversion cost in Plymouth?
A mid-range 30 m² dormer loft conversion in Plymouth costs about £58,500 to £72,500 including VAT for the building work, and about £73,000 to £93,000 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