Basement construction in Clapham.
Fulham · SW6 · Fulham basementsCompleted work, photograph
Basements under Clapham terraces, designed to Lambeth’s Policy Q27. Engineered, priced and built by one team.
A Clapham basement, with the garden kept.
- Q27, 2021
- Lambeth’s basement policy
- 70 per cent
- Of the rear garden kept undug
- One storey
- Below an existing house
NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle basement conversion and construction in Clapham SW4, 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.
Clapham is mostly Victorian terraces, with longer gardens than Chelsea or Kensington.
Lambeth allows one storey of basement under an existing house.
Beyond the house, a basement may only extend to the rear.
Its roof must sit at garden level, so the space above stays usable.
At least 70 per cent of the rear garden generally stays undug.
Our basements are in Fulham and Chelsea. In Clapham we have made joinery for a house.
What Lambeth allows below a Clapham house.
- Council
- London Borough of Lambeth, under its Local Plan adopted in September 2021.
- Policy Q27
- One storey below ground, and none beneath an existing basement.
- The garden
- Beyond the footprint, rear only, with 70 per cent of the garden kept.
- Front lightwells
- Only where needed for daylight. In conservation areas, grilles rather than open areas are likely.
- Assessment
- A Stage 1 Basement Impact Assessment goes in with the application. A qualified professional prepares it.
- Flooding
- A positive pumped device protects the basement from sewer flooding.
Source: Lambeth Local Plan 2021, Policy Q27 Basement development. Read on 7 October 2026. Policies change, so we read them again for your address.
Basements we have built, and our Clapham work.
Fulham·Basements
Fulham basements
Basements dug, waterproofed and finished by our own team, under Fulham terraces.
See the project
Clapham·Joinery
Clapham bespoke joinery
A Clapham house, its cabinetry and wine storage made by Cochrane Bespoke.
See the projectCompleted work, photographs
What basement construction costs in Clapham.
£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 guide figures are whole project totals.
Fees, party wall costs, contingency and VAT sit outside both.
Open the calculatorThe 2026 cost guideBasement costs in full
What Clapham owners ask about basements.
In Clapham
Basements nearby
- Basement construction across London
- Basement construction in Fulham
- Basement construction in Chelsea
- Basement construction in Kensington
- 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
- Wandsworth, Putney and Barnes
- Brixton
- Dulwich
Further reading, from the journal
How deep can a Clapham basement go?
One storey below ground, under Lambeth’s Policy Q27.
A second level under an existing cellar is not supported.
How much of a Clapham garden can a basement take?
Lambeth generally keeps at least 70 per cent of the rear garden undug.
The built part sits at garden level, so the space above stays usable.
What is a Basement Impact Assessment in Lambeth?
A Stage 1 screening report by a qualified professional, sent with the application.
It covers groundwater, ground stability, flooding, heritage and nearby basements.
Lambeth may ask for further stages, and the applicant pays for their review.
Can I dig a lightwell at the front of a Clapham house?
Only where the rooms need it for daylight and outlook.
In conservation areas, pavement grilles are likely instead of open areas.
What does a basement cost in Clapham?
Our basement band runs £450 to £780 a sq ft, construction only.
Converting a cellar is £180k to £300k as a project total.
A new dig runs £500k to £900k and more in our 2026 cost guide.
Tell us about your home in Clapham.
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