Basement conversions are among the most complex renovation projects. Costs include underpinning or lowering the slab, structural waterproofing (tanking), ventilation, lighting design, and full fit-out of the new space. In Belgravia (SW1), costs reflect the area's Prime Central London market position, with a 25% premium over London averages.
Belgravia is London's grandest residential neighbourhood, characterised by sweeping stucco-fronted crescents and garden squares designed by Thomas Cubitt in the 1820s. Properties here are among the most valuable in the world.
| Specification | Price per sqm | Typical 40sqm Project | Includes |
|---|---|---|---|
|
Standard
Quality materials, clean design
|
£3,750 – £5,000 | £150,000 – £200,000 | All structural work, standard fixtures, full fit-out and decoration |
|
Premium
Designer brands, bespoke elements
|
£5,000 – £6,875 | £200,000 – £275,000 | Premium materials, designer fixtures, underfloor heating, smart controls |
|
Luxury
Finest materials, fully bespoke
|
£6,875 – £10,000 | £275,000 – £400,000 | Bespoke joinery, natural stone, top-tier appliances, architectural detailing |
Prices include VAT and are based on Belgravia (SW1) market rates. Prime Central London pricing reflects the premium specification expectations and specialist requirements typical in this area. Actual costs depend on site-specific factors. All prices are guide estimates for 2025.
Here's what a typical 40sqm basement conversion project would cost in Belgravia at each specification level.
The Belgravia Conservation Area is one of London's most strictly protected. The Grosvenor Estate maintains additional architectural controls beyond statutory planning requirements.
Key streets and roads in Belgravia include Eaton Square, Chester Square, Belgrave Square, Wilton Crescent, Eaton Place. Properties in these locations often have specific architectural characteristics that influence renovation costs, including Grosvenor Estate licence and design approval required, ultra-premium specification expectations, complex basement regulations, strict construction management plans required, specialist stucco restoration.
Every basement conversion is unique. Let our RIBA chartered architects provide a detailed, no-obligation estimate tailored to your property and specification.
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