Cost Guide 2025

House Extension Cost in Belgravia

A house extension can transform your home, adding valuable living space. Costs cover foundations, structural work, roofing, glazing, internal fit-out, and connection to existing services. In Belgravia (SW1), costs reflect the area's Prime Central London market position, with a 25% premium over London averages.

£3,125 – £6,875/sqm Estimated range for
Belgravia (SW1)

House Extension Costs in Belgravia

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 25sqm Project Includes
Standard
Quality materials, clean design
£3,125 – £4,000 £78,125 – £100,000 All structural work, standard fixtures, full fit-out and decoration
Premium
Designer brands, bespoke elements
£4,000 – £5,000 £100,000 – £125,000 Premium materials, designer fixtures, underfloor heating, smart controls
Luxury
Finest materials, fully bespoke
£5,000 – £6,875 £125,000 – £171,875 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.

A 25sqm House Extension in Belgravia

Here's what a typical 25sqm house extension project would cost in Belgravia at each specification level.

Standard
£78,125 – £100,000
25sqm at £3,125–£4,000/sqm
Quality materials, clean finish
Premium
£100,000 – £125,000
25sqm at £4,000–£5,000/sqm
Designer brands, bespoke elements
Luxury
£125,000 – £171,875
25sqm at £5,000–£6,875/sqm
Finest materials, fully bespoke

What Affects House Extension Costs in Belgravia

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.

  • Foundation requirements and ground conditions
  • Proximity to boundaries and neighbours
  • Roof design — flat, pitched or glazed
  • Level of glazing and bi-fold doors
  • Connection to existing structure

Belgravia Area Profile

Postcodes: SW1

Market tier: Prime Central London

Price adjustment: +25% vs base London rates

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.

Belgravia: ×1.25 multiplier

Get a Precise Quote for Your Belgravia Project

Every house extension is unique. Let our RIBA chartered architects provide a detailed, no-obligation estimate tailored to your property and specification.

Use our interactive calculator for a personalised estimate

House Extension in Belgravia — FAQs

How much does a house extension cost in Belgravia?
House extensions in Belgravia cost between £2,200-£4,000/sqm depending on specification. A standard 25sqm rear extension starts around £55,000, while a premium specification with high-end finishes can exceed £80,000-£100,000.
Do I need planning permission for a house extension in Belgravia?
Many single-storey rear extensions of up to 6m (detached) or 3m (terraced/semi) fall under permitted development. However, properties in conservation areas in Belgravia often have restricted PD rights. We provide full planning guidance for every project.
How long does a house extension take in Belgravia?
A typical ground-floor rear extension takes 10-16 weeks on site. Side-return extensions are often quicker at 8-12 weeks. Double-storey extensions may take 14-20 weeks. Access constraints in Belgravia can affect programme.
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