ExtensionsKensington W8
House extensions in Kensington.
Extensions for Kensington terraces, villas and garden flats. Drawn to the borough’s CD13 tests, priced open book, built by one team.
Extending a Kensington house from the back.
NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle house and kitchen extensions in Kensington W8, under one contract. A rear extension runs £280 to £320 a sq ft, construction only. A side return runs £310 to £340 a sq ft. Call 020 7731 6841, and a budget estimate typically follows within seven days.
Kensington runs from stucco terraces to brick villas. Many houses back onto communal gardens.
The borough treats those garden sides with care. A rear elevation can matter as much as the street front.
So an extension here is drawn to the whole terrace, not just the plot.
Many houses are split into flats. A garden flat extension needs the freeholder’s licence as well.
We price it open book, and the same team builds it.
What the council allows.
- Council
- Royal Borough of Kensington and Chelsea, which covers all of Kensington.
- Communal gardens
- Rear elevations facing communal gardens may matter as much as fronts, the plan says.
- Symmetry
- An extension must not unbalance a terrace’s symmetry or close an important gap.
- Rear additions
- Policy CD13. Keep the even rhythm of rear additions, and stay below the eaves.
- Access
- It must not cut off rear access, for the house or its neighbours.
Source: Kensington and Chelsea’s Local Plan 2024, Policies CD4, CD5, CD11 and CD13. Read on 3 October 2026. Policies change, so we read them again for your address.
Built under the same rules.
Chelsea·Townhouse
Chelsea basement and extension
A kitchen extension and a new basement in Chelsea, in the same borough.
See the project
Kensington·New build
Kensington new-build houses
Two new houses we built in the same borough. Living rooms open onto light wells.
See the projectCompleted work, photographs
What it costs.
£280 to £320a sq ft, construction only. Our rear extension band.
£310 to £340a sq ft, construction only. Our side return band.
£200k to £320kA wraparound extension. A project total, from our 2026 cost guide.
A garden flat and a whole house price very differently.
Bands are per square foot, construction only. Guide figures are project totals.
Fees, party wall costs, contingency and VAT sit outside both.
Extensions in Kensington, answered.
Can I extend a Kensington house that backs onto a communal garden?
Often, but the garden side is judged closely.
The borough treats those rear elevations almost as carefully as the front.
We draw the extension against the whole terrace, as seen from the garden.
Can a Kensington garden flat be extended?
Sometimes, if the flat owns the garden and the freeholder agrees.
Your lease will say whether structural work needs consent.
The borough’s CD13 tests then apply as they would to a house.
Do I need planning permission for a rear extension in Kensington?
Often. Permitted development is narrower in a conservation area.
Flats have no householder permitted development rights at all.
We check the house’s status before anything is drawn.
Will my neighbours need party wall notices for a Kensington extension?
Usually, where the work is on or near a shared wall.
Notices go out before work starts.
We run that alongside the design, so it does not hold the build.
What does an extension in Kensington cost?
A rear extension runs £280 to £320 a sq ft, construction only.
A side return runs £310 to £340 a sq ft.
Our 2026 cost guide puts a wraparound at £200k to £320k in total.
Related pages.
From the journal358 notes, free to read
Kensington, written up.
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3 min read
Planning permission for a London extension: timing and refusals
A decision date is not a start date. What sits either side of the council decision, plus pre-application advice and refusals.
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4 min read
Side return or rear extension? Cost and how to choose
Side return or rear extension for a London terrace? What each one is, what moves the cost of each, and how a design and build contractor chooses.
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3 min read
Rear extension cost in London, what the number covers
What a London rear extension costs per square foot. What the build rate covers, what moves it, and how it compares with a side return.
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Extensions, Kensington
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