Cost Guide 2025

House Extension Cost in South Kensington

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 South Kensington (SW7), 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
South Kensington (SW7)

House Extension Costs in South Kensington

South Kensington is a prestigious area home to world-renowned museums, embassies, and some of London's finest stucco-fronted terraces. Properties here command premium prices and demand the highest quality renovation.

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 South Kensington (SW7) 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 South Kensington

Here's what a typical 25sqm house extension project would cost in South Kensington 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 South Kensington

Extensive conservation areas across South Kensington strictly control all external alterations. White stucco facades must be maintained to exact specifications.

Key streets and roads in South Kensington include Onslow Square, Pelham Crescent, Thurloe Square, Sumner Place, Queen's Gate. Properties in these locations often have specific architectural characteristics that influence renovation costs, including stucco facade maintenance requirements, RBKC basement development restrictions, embassy security considerations, premium specification expectations.

  • 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

South Kensington Area Profile

Postcodes: SW7

Market tier: Prime Central London

Price adjustment: +25% vs base London rates

South Kensington is a prestigious area home to world-renowned museums, embassies, and some of London's finest stucco-fronted terraces. Properties here command premium prices and demand the highest quality renovation.

South Kensington: ×1.25 multiplier

Get a Precise Quote for Your South Kensington 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 South Kensington — FAQs

How much does a house extension cost in South Kensington?
House extensions in South Kensington 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 South Kensington?
Many single-storey rear extensions of up to 6m (detached) or 3m (terraced/semi) fall under permitted development. However, properties in conservation areas in South Kensington often have restricted PD rights. We provide full planning guidance for every project.
How long does a house extension take in South Kensington?
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 South Kensington can affect programme.
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