House Extensions South Kensington

GS Renovation builds extensions across South Kensington, from rear additions to full wrap-around projects on the Victorian and late Georgian townhouses of the museum quarter. We manage the groundworks, steel, roof and fit-out as one project.

In South Kensington, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in South Kensington: the structural engineer we appoint designs the structure, we build it, and building control signs it off.

Kitchen extensions, rear additions and side return infills in South Kensington

The usual kitchen extension in South Kensington is a modest addition at lower ground or garden level, built to turn a dark lower-ground kitchen into a proper kitchen-diner. What would be a side return infill elsewhere is here the gap between closet wings, and the conservation area appraisals push back hard on infilling it, and Policy CD13 holds depth and height to the line of neighbouring extensions, so the scheme that gets approved is usually a lower, lighter addition that keeps the rhythm of the rear wings. We dig and lay foundations suited to the ground and the neighbouring structures, then tie the new build into the original brickwork with steel where the old rear wall is removed.

Plots in SW7 are often tight and hemmed in by neighbours on both sides, so we plan access, waste removal and material handling carefully. A steel beam sized by the engineer usually spans the new opening, and building control inspects the foundations, the structure and the finished envelope before the space is signed off.

Housing in South Kensington

Roughly 8,840 dwellings sit on the valuation list for South Kensington. 15% are houses and 85% flats, and by age 84% predate 1919, 3% are interwar and 12% post-war. Most homes here are flats, and a flat in South Kensington has no householder permitted development rights, so extending one needs planning permission and the freeholder's consent.

Sizing a South Kensington extension against the Brompton appraisal

Only a small part of the housing in South Kensington can extend as a house at all: 13% of homes are terraced houses and 2% are semi-detached or detached. A single storey rear extension within the size limits can still be permitted development for a house in a conservation area, unless those rights have been removed at the address. Anything larger is an application, and for houses in the Brompton Conservation Area the appraisal lists domestic extensions, including oversized rear extensions and roof additions, among the negative elements harming the area. That application is weighed on size relative to the house and the terrace, so the design starts from the smallest room that does the job.

Two practical items belong at the start as well. Kensington and Chelsea is in Mayoral CIL charging Band 1. Where an extension is large enough to be liable, the exemption for extending your own home has to be claimed before work starts, so the claim belongs in the pre-start paperwork rather than being tidied up afterwards. And a new footing beside a period house usually goes deeper than the old one next door, which brings the excavation rules of the Party Wall etc. Act into play. The building owner serves that notice, and in South Kensington the award is agreed before the digger arrives.

Planning and party walls in South Kensington

Whether your extension is permitted development or needs a full planning application depends entirely on the property. Many South Kensington houses sit within a conservation area and a good number are listed, which tightens permitted development rights considerably: a single storey rear extension to an unlisted house can still be permitted development in a conservation area unless an Article 4 direction removes it, but side, two-storey and roof additions are not, flats have no householder permitted development, and listed houses need listed building consent. A submission to the Royal Borough of Kensington and Chelsea is therefore often required. We advise honestly on which route your SW7 house falls under before any work starts.

Because the houses are terraced and share party walls, most extension projects trigger the Party Wall etc. Act, meaning you, as building owner, serve notice on the adjoining owners (or your surveyor does). We coordinate the drawings, the timing around the party wall process and the building regulations approvals so the paperwork and the programme move together rather than holding one another up.

Building at the back of a townhouse

A rear extension in South Kensington is built in a garden that can usually only be reached through the house, and that single fact shapes the entire job. Excavated spoil, concrete, blockwork, steel and glass all have to travel along a protected route through finished rooms, or be lifted over. Where a neighbour is willing to allow it, access through their side is sometimes quicker and we will always ask the question. Scaffold is the other early decision, because where it stands governs which route stays open for materials throughout the build.

Concrete is the hardest item to manage. A ready mixed load cannot be barrowed far, so we plan either for a pump or for mixing on site depending on what the street will take. Waste is bagged and lifted where there is no frontage to stand a skip on. All of this is settled before a start date is offered, because in SW7 the access strategy often decides the programme more than the building work does.

With 85% of homes in South Kensington flats, double storey extensions belong to the few houses here; a flat has no householder permitted development, so any extension to one needs planning permission from the Royal Borough of Kensington and Chelsea and the freeholder's consent.

• Building control inspections at foundation, damp course and steel stages
• Party wall process explained, and the extension built to the award
• Wrap-around extensions and infills

VOA Council Tax stock of properties, March 2025, for South Kensington and Queen's Gate. Counts rounded by the VOA.

Related reading for South Kensington homeowners planning house extensions: RSJ and steel beam installation in South Kensington, house extensions across Kensington and Chelsea, wraparound extensions, party walls and extensions, our London house extensions page and Side Return vs Rear Extension.

Why Choose GS Renovation in South Kensington

South Kensington homeowners choose GS Renovation because we handle an extension end to end, from the first planning conversation with the council to the final coat of paint. We understand conservation-area and listed constraints in SW7, programme properly around the party wall process, and build to last. Our founder's 30+ years on the tools underpins the work.

• Insulation and thermal detailing to current regulations
• Building control inspected at foundation, damp course and steel stages
• Photographs kept at each stage for your records

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.