Basement construction in Kensington.
Kensington · W8 · Kensington new-build housesCompleted work, photograph
Basements under Kensington terraces and villas, within the borough’s one storey rule. Engineered, monitored and built by one team.
Basements under the one storey rule.
- RBKC
- The borough that wrote CL7
- One storey
- Under half the garden at most
- W8
- Terraces, garden flats and villas
NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle basement conversion and construction in Kensington W8, under one contract. A basement runs £450 to £780 a sq ft, construction only. Call 020 7731 6841, and a budget estimate typically follows within seven days.
Kensington runs from stucco terraces to brick villas on the hill. Many houses are split into garden flats.
Many terraces back onto communal gardens, so the house’s own garden is often small.
Kensington and Chelsea was the first council to limit how far basements go. Its rule, now Policy CD11, sets one storey under half the garden.
Every Kensington basement now needs planning. We prepare the application, the structure and the traffic plan together.
What the council allows in Kensington.
- Council
- Royal Borough of Kensington and Chelsea, which covers all of Kensington.
- Extent
- CL7, adopted January 2015, was the first policy to limit basement extent. Since 2024 it is Policy CD11.
- Later changes
- Under the 2016 Basements SPD, the storey cannot be split into two floors later.
- Planning
- An Article 4 direction since April 2016 means every basement needs planning.
- On site
- A Construction Traffic Management Plan goes in with the application. The Code of Construction Practice, revised 2019, governs the site.
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.
Dug and built in the borough.
Kensington·New build
Kensington new-build houses
Our dig for two new houses here in Kensington, three floors down.
See the project
Chelsea·Townhouse
Chelsea basement and extension
A new basement and kitchen extension in Chelsea, in the same borough.
See the projectCompleted work, photographs
What a basement costs in Kensington.
£450 to £780a sq ft, construction only. Our basement band.
£180k to £300kConverting an existing basement. A project total, from our 2026 cost guide.
£500k to £900k+Digging a new basement. A project total, from our 2026 cost guide.
The band is a rate per square foot, construction only.
The cost guide figures are whole project totals, before fees, contingency and VAT.
A garden flat, a terrace and a villa each price differently. So we price the house itself.
Open the calculatorThe 2026 cost guideBasement costs in full
What Kensington owners ask about basements.
In Kensington
- Every service in Kensington
- House extensions in Kensington
- Luxury refurbishment in Kensington
- Interior design in Kensington
- Party wall surveying in Kensington
- Architects in Kensington
Basements nearby
- Basement construction across London
- Basement construction in Fulham
- Basement construction in Chelsea
- Basement construction in St John’s Wood
- Basement construction in South Kensington
- Basement construction in Knightsbridge
- Basement construction in Belgravia
- Basement construction in Holland Park
- Basement construction in Hampstead
- Basement construction in Notting Hill
- Basement construction in Clapham
- Notting Hill and Holland Park
- South Kensington
- Chelsea
Further reading, from the journal
Can I dig a basement under a Kensington garden flat?
Sometimes, if the flat owns its garden and the freeholder agrees.
The lease usually needs a licence for structural work.
Policy CD11 still applies, one storey under half the garden.
Why did Kensington and Chelsea limit basements?
The council wanted to limit the disruption of large basement digs.
It adopted CL7 in January 2015 to limit their extent.
Can I extend an existing cellar in Kensington?
Yes, within Policy CD11. The rules cover extensions to existing basements too.
Lowering an existing cellar is often the simplest route.
We survey it first and test the depth against the policy.
What does a Kensington basement cost?
Our basement band is £450 to £780 a sq ft, construction only.
A new dig runs £500k to £900k and more, as a project total.
A conversion of an existing basement runs £180k to £300k.
Tell us about your home in Kensington.
Your name and one way to reply are enough. It goes straight to the studio.
- Already have an architect or designer? We build to their design. Working with your designer
- An NDA on request, and your home is never published without your consent. How we work in confidence