House
extensions
in Kensington, W8
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Hampstead Chartered Surveyors & Building ConsultancyKensington's rear elevations come in two kinds, plain rears with closet wings and formal rears onto communal gardens, and each takes a different extension.
House extensions in Kensington: what actually drives consent and buildability
Kensington extensions: plain rears and formal ones
The Kensington appraisal identifies two types of rear elevation. Most houses have plain rears with closet wings that usually project about halfway across and typically stop at least a storey below the eaves.
The void beside those wings has often been filled at lower ground floor with conservatory-type extensions, and where later extensions infill it the rear becomes solid and flat, losing its articulation.
The second type backs onto communal gardens, with formal rears in good brick and decorative finishes, seen in views east across Holland Park; alterations and extensions to those can be extremely harmful, breaking the composition and the rhythm along the terrace.
Many rear elevations can also be seen from side streets, and the appraisal records that rebuilding rear elevations has harmed the conservation area.
Gaps above garages and over single-storey rear additions count in the townscape, so a storey added over an existing addition is checked against the view it would close.
Policy CD13 measures depth and height by the neighbours' extensions, and in a listed house an extension needs listed building consent, as other larger changes do.
The Phillimore Estate's semi-detached villas of 1855 to 1870, some with substantial gardens behind, give more room for an extension than the yard-backed terraces of the eastern half.
Under the borough's Code a residential extension is Category 2: a signed checklist and a site construction management plan are approved before work starts, and neighbours are told well before the application goes in.
On the north side of Bedford Gardens, numbers 48 to 74 are the seven pairs of semi-detached houses completed in 1836; extensions, new windows, render and paint have altered them over the years, and in some cases the pairs have been unbalanced.
Behind them, the south side of Campden Street, numbers 54 to 71, was built within the rear gardens of the north side of Bedford Gardens, and a number of mews styles have grown up there.
On a semi-detached pair we draw both halves, so an extension to one side keeps the pair in balance.
We establish first which of the two rear types the house has, because a formal rear onto a communal garden and a plain rear onto a yard call for different extensions.
Sources: Royal Borough of Kensington and Chelsea: Kensington Conservation Area Appraisal; Royal Borough of Kensington and Chelsea: Local Plan (adopted July 2024); Royal Borough of Kensington and Chelsea: listed buildings explained; Royal Borough of Kensington and Chelsea: Code of Construction Practice.
House Extensions in Kensington: Questions
Can I fill the gap beside my closet wing in Kensington?
Often at lower ground floor, where conservatory-type extensions are common, but the appraisal warns that infilling the whole void leaves the rear solid and flat, and formal rears onto communal gardens are far more sensitive.
Do permitted development rights still apply to house extensions in Kensington?
Less than owners expect. RBKC has made Article 4 directions that strip permitted development rights for external works — window and front-door replacement, boundary walls, roof coverings and other front-elevation changes — from properties on streets including Kensington Square, Kensington Court Place and Kensington Church Street. Across the borough, 38 conservation areas cover nearly three quarters of the land, and proposals within them must preserve or enhance historic character — so we plan Kensington extensions as full applications from the start.
What does the planning application for a Kensington extension involve?
Making the conservation case. Kensington lies within the Kensington Conservation Area, on some of the most valuable residential streets in London, and RBKC requires proposals in its conservation areas to preserve or enhance their historic or architectural character or appearance. That test is the spine of the application — and early command of the borough's rules is what keeps a Kensington application on course, so we resolve them before the design is committed.
Which Kensington houses lend themselves to extension?
Kensington's houses are grand Victorian and Georgian townhouses and stucco terraces gathered around Campden Hill, Kensington Church Street and the Phillimore and Pembroke estates; most are listed or of group value, and the area is largely leasehold, which shapes the consent route. The garden-square terraces of Pembroke and Phillimore Gardens are natural candidates for reconfiguration, of which an extension is often one part.
How much should I allow for a house extension in Kensington?
A single-storey rear extension and a side return are each priced excluding VAT. A Kensington scheme is then priced against its own design and consents rather than against a headline figure.
Who else, besides RBKC, must approve a Kensington house extension?
Often the estate or the freeholder. In Kensington, estate and freeholder consent runs alongside the planning decision, and where the property is a leasehold flat, freeholder or council approval — frequently a Licence to Alter covering layout and services work — is needed as well. We run those consents in parallel with the RBKC application so the programme stays whole.
