Rear courtyard with a glass rooflight set into the paving.

House extensions in Cobham.

Fulham · SW6 · Fulham, four new-build houses with basementsCompleted work, photograph

In Cobham the first question is the Green Belt. It sets how much a house may grow above ground.

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Extending inside the Green Belt.

Volume cap
Green Belt additions are measured
Below ground
A buried floor can sit outside the cap
KT11
Detached houses on private estates

NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle house and kitchen extensions in Cobham KT11, under one contract. A rear kitchen extension typically runs £160k to £250k. A side return extension typically runs £140k to £220k. Call 020 7731 6841, and a budget estimate typically follows within seven days.

Cobham houses sit on generous plots, often on private estates. Beyond the town edge the land is Green Belt.

There, every addition joins a running total of volume and footprint. A garden room and a dormer both count.

So we often split the brief. Living space goes below ground, where a wholly buried floor escapes the cap.

Above ground, we keep the addition tight and well lit. Height and glazing do more than floor area.

In the town, conservation areas apply instead. Boundary changes fall under two Article 4 directions.

What the council allows in Cobham.

Council
Elmbridge Borough Council, Development Management Plan, 2015.
Green Belt
Each extension adds to a volume and footprint limit.
Below ground
DM18 exempts a floor wholly underground, inside the footprint, with discreet lightwells.
Conservation areas
Cobham dates from July 1973, Plough Corner from November 1990. The Tilt too.
Boundaries
Two Article 4 directions cover gates, fences, walls and temporary buildings.

Source: Elmbridge Development Management Plan 2015, Policy DM18, and its conservation areas list. Read on 25 October 2026. Policies change, so we read them again for your address.

What we have built in London.

Staircase with pale treads and lit niches in the wall.

Fulham·New build

Fulham, four new-build houses with basements

Four new houses with basements we built in Fulham SW6. Our Surrey work is still to come.

See the project

Completed work, photographs

What a house extension costs in Cobham.

£200k to £320kA wraparound extension. A project total, from our 2026 cost guide.

We have not yet completed a project in Surrey.

The guide figure is a London project total, before fees and VAT.

Open the calculatorThe 2026 cost guideCan I build it here?

How much can a Green Belt house in Cobham grow?

Additions are held to a volume and footprint limit.

We measure the house as it stands, then plan within it.

Should a Cobham extension go down instead of out?

Often, on Green Belt land.

A floor wholly underground, within the footprint, sits outside the limit.

Discreet lightwells keep it bright.

Will a new garden wall for my Cobham extension need planning?

It may. Two Cobham Article 4 directions cover gates, fences and walls.

Temporary buildings are covered too.

What does a wraparound extension in Cobham cost?

Our 2026 cost guide puts a wraparound at £200k to £320k in total.

No Surrey project is finished yet, so this is a London figure.

Tell us about your home in Cobham.

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What is the work?

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