Kensington & Chelsea, London
Boroughs · West London
Kensington & Chelsea · Prime central

House extensions in Kensington & Chelsea

London's most demanding borough for extension consenting. Every project needs a heritage-fluent architect and a builder used to premium-listed work.

Typical all-in (inc VAT)
£180k–£300k
Cost vs London base
+20%
Postcodes covered
SW3 · SW5 · SW7 · SW10

Housing stock in Kensington & Chelsea

Stucco terraces, mansion blocks, Georgian and early-Victorian townhouses — mostly Grade II.

Basement extensionRear infillRoof / mansard

Planning in Kensington & Chelsea

RBKC is the strictest planning authority in London for extensions. Basement policy is tight (post-2015), Article 4 removes PD in most zones, and heritage officers scrutinise everything.

Party Wall Act — what to expect

Basement work almost always triggers major Party Wall Awards on both flanks — plan for surveyors on all sides.

Read the Party Wall etc. Act 1996 guide for full detail on notices, timelines and surveyor costs.

Typical costs in Kensington & Chelsea

For a mid-spec 25 m² kitchen extension, all-in (professional fees, planning, party wall, VAT and 12% contingency), expect roughly £180,000 to £300,000. High-spec finishes, structural glazing or a full basement dig-out will push above the top of this range; a smaller side-return can come in under the bottom.

Cost tier
Prime central · +20% vs London average

Our calculator applies a 1.20× multiplier automatically for Kensington & Chelsea projects. Get an itemised breakdown in 60 seconds.

Get your Kensington & Chelsea estimate

Areas we cover in Kensington & Chelsea

SW3SW5SW7SW10W8W11W10

Why homeowners in Kensington & Chelsea pick us

  • KYB-verified builders only
  • Local Kensington & Chelsea project experience
  • Fixed, itemised written quotes
  • Full insurance & warranty checks
Call now WhatsApp