Extension & Loft Conversion Costs by City and Area (2026)
Quick answer
A standard 30m² rear dormer loft conversion costs from about £43,500–£66,500 in Manchester and Leeds to £58,500–£88,500 in London in 2026, including design, structural engineer, approvals and VAT. A 20m² single-storey extension ranges from about £52,000–£68,500 in the North to £70,000–£91,500 in London. Each city guide below explains local planning rules, housing types, permits and house prices.
2026 costs compared by city and area
| City | Rear dormer loft (30m²) | Single-storey extension (20m²) | Local guide |
|---|---|---|---|
| London | £58,500 – £88,500 | £70,000 – £91,500 | Lofts · Extensions |
| Beckton (Newham) | £58,500 – £88,500 | £70,000 – £91,500 | Beckton guide |
| Leatherhead (Mole Valley) | £53,000 – £80,000 | £63,000 – £82,500 | Leatherhead guide |
| Maidstone | £53,000 – £80,000 | £63,000 – £82,500 | Maidstone guide |
| Portsmouth | £53,000 – £80,000 | £63,000 – £82,500 | Portsmouth guide |
| Bristol | £49,000 – £74,500 | £58,500 – £77,000 | Bristol guide |
| Essex | £49,000 – £74,500 | £58,500 – £77,000 | Essex guide |
| Peterborough | £49,000 – £74,500 | £58,500 – £77,000 | Peterborough guide |
| Birmingham | £46,500 – £70,500 | £55,500 – £72,500 | Birmingham guide |
| Nottingham | £46,500 – £70,500 | £55,500 – £72,500 | Nottingham guide |
| Glasgow | £45,500 – £68,500* | £54,500 – £70,500 | Glasgow guide |
| Manchester | £43,500 – £66,500 | £52,000 – £68,500 | Manchester guide |
| Leeds | £43,500 – £66,500 | £52,000 – £68,500 | Leeds guide |
| Liverpool | £43,500 – £66,500 | £52,000 – £68,500 | Liverpool guide |
| Llanelli | £43,500 – £66,500 | £52,000 – £68,500 | Llanelli guide |
Why costs differ between cities
- Labour and overheads: London rates run roughly a quarter above the Midlands; the North of England, Wales and Scotland sit below the national base.
- Housing stock: Victorian terraces suit rear dormers and side returns; 1930s semis suit hip to gable conversions; Leeds back-to-backs and Glasgow tenements bring their own limits.
- Planning: conservation areas and Article 4 directions remove permitted development rights, adding a planning fee and design time.
- Access: scaffold licences, skip permits, parking and steep streets add cost in dense areas.
- Scotland is different: building warrants replace building control, there is no Party Wall Act, and planning fees and permitted development rules differ.
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