Find out how much a basement conversion costs in the UK. Compare average prices, explore conversion options, and receive free quotes from trusted local basement conversion specialists.
London basement conversions are among the most expensive in the UK due to high labour costs, complex ground conditions, and strict planning regulations. However, they also offer the highest return on investment, often adding 15-20% to property values in prime areas.
| Project scope | Average cost |
|---|---|
| Basic cellar conversion (20m²) | £35,000 – £45,000 |
| Mid-range conversion (30m²) | £50,000 – £65,000 |
| High-end conversion (40m²) | £70,000 – £90,000 |
| Luxury with excavation (50m²+) | £100,000 – £150,000 |
Our vetted specialists carry out basement conversions across Kensington, Chelsea, Fulham, Hammersmith, Islington, Camden, Hampstead, Clapham, Battersea, Greenwich and the wider Greater London area, covering cellar conversions, full excavations, underpinning and waterproofing.