Kitchen Extensions Hampstead

A kitchen extension in Hampstead begins with what kind of home you own. 78% of homes here are flats and 22% are houses, and householder permitted development rules for extensions cover houses only, not flats and maisonettes. So a house owner in NW3 weighs a rear or wraparound kitchen against Camden's guidance, while a garden flat owner starts with a planning application. Either way we build the shell, the drainage and the new kitchen in one programme, so the room is finished by the same team that dug the footings.

In Hampstead, a rear kitchen extension of about 30 square metres typically costs £45,000 to £97,500 excluding VAT, or £60,000 to £100,000 for a side return (indicative London ranges, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Hampstead: the structural engineer we appoint designs the foundations and steel, we build the room and fit the kitchen, and a registered electrician certifies the electrics.

What kitchen extension a Hampstead house can take

A Hampstead house can take a single storey rear kitchen extension that stays subordinate to the original building, and on a wider plot a wraparound that also fills the side. 11% of homes here are terraced houses and 11% are semi-detached or detached, and the site describes the stock as period cottages and substantial Victorian villas. On a cottage the back wall is low and the garden can be short, so the extension tends to be shallow and the steel the engineer specifies over the new opening is modest. On a villa the rear elevation is taller and the back rooms deeper, which leaves more to play with.

Camden's Home Improvements guidance sets the frame for both. It says a rear extension should be subordinate to the house in location, form, footprint, scale, proportions, dimensions and detailing, and should leave a reasonably sized garden. That means your designer tests the depth against the garden before drawing the glazing, not after. For us the footprint fixes the dig: how far the foundations run, where the new drain goes and how much spoil has to leave through a side passage or through the house.

Housing in Hampstead

Hampstead's housing, as the Council Tax list records it, is about 11,670 homes: 22% houses, 78% flats, with 63% pre-1919, 10% interwar and 27% built since 1945. Since most homes here are flats, only a ground floor flat in Hampstead with its own garden can extend its kitchen.

Conservation area rules and daylight tests in NW3

Check the conservation area first, because it changes the paperwork before anything is dug. The Hampstead Conservation Area was designated on 29 January 1968, together with North End, the Elms, Vale of Health and Downshire Hill, and your designer confirms whether your street is inside it. Camden's guidance says properties in conservation areas have no permitted development rights for side extensions or two storey extensions, so a wraparound there goes through a householder application. That application must include a heritage statement describing the significance of the heritage assets affected, which your designer or agent writes and which often settles the brick and roof form we then order.

Your neighbours' light is the second test. Camden's guidance asks rear extensions to meet the 45 degree and 25 degree tests in its Amenity guidance, or to show BRE compliance through a daylight test. Where a Hampstead villa stands close to the next house, those lines can cap the height of the boundary wall or pull a pitched roof down toward the fence. We build to the section that passes. Parapet height, roof fall and gutter detail all follow from it, so any change on site goes back to the designer rather than being settled with a trowel.

Garden flats, basements and why planning comes first

A Hampstead garden flat can gain a bigger kitchen, but only through a planning application, because householder permitted development rules for extensions apply to houses only and not to flats and maisonettes. With 78% of homes here flats, that rule reaches a large part of NW3. The lease matters as much as the permission: the freeholder's consent, the managing agent's conditions and the other flats' access over the garden all shape where the site welfare goes, how materials arrive and which days the noisy work can run.

Some owners ask about digging down to put the kitchen on a new or deeper lower ground floor. Camden's Article 4 direction on basements, adopted on 1 June 2017, covers the whole borough, so every basement excavation needs planning permission. Camden also requires a site specific Basement Impact Assessment with any application that includes a new or extended basement. Excavating near a neighbour's foundations can also be notifiable under the Party Wall Act, and the building owner serves those notices. If the brief can be met at garden level, keeping the new kitchen there keeps the job on a simpler footing, and we can price both options so the difference is clear.

Roof lights, green roofs and the kitchen fit-out

The roof of a Hampstead kitchen extension is shaped by Camden's guidance as much as by the design. It says roof lights on ground floor extensions should sit away from the building line or be obscure glazed, to avoid light spilling up at the windows above. It also prefers biodiverse green roofs with a substrate depth of 100mm to sedum roofs. That depth adds weight when wet, so the joists, the upstands and the outlets are sized for it from the start, and the roof light kerbs are set before the membrane goes down.

Trees are the last thing to clear before the dig. In a conservation area Camden requires six weeks' notice before work on any tree with a trunk diameter of more than 75mm at 1.5 metres, so a root that sits in the line of the footings has to be planned for early. Once the shell is watertight the programme runs straight on: first fix wiring and plumbing, plaster, floor, then the units, worktops and appliances. A registered electrician checks the first fix before the walls are closed, then tests and certifies the new circuits before handover.

• New kitchen circuits, with Part P certification from a registered electrician
• Airbrick ducts to keep existing timber floors ventilated
• Cooker hood extraction ducted through the roof or flank wall

VOA Council Tax stock of properties, March 2025, for Hampstead Town, Frognal and Fitzjohns & Royal Free. Counts rounded by the VOA.

Two or three things usually come up alongside kitchen extensions on a Hampstead job: kitchen renovation in Hampstead, kitchen extensions across Camden, fitting the kitchen itself, the Party Wall Act on a boundary build, our London kitchen extensions page and Getting Daylight Into a Deep Plan.

The GS Renovation Difference in Hampstead

You deal with one firm from the first dig to the last worktop joint. The structural engineer we appoint designs the steel into the old back wall, and our own trades run the groundworks, drainage, shell, roof and kitchen fitting in one sequence. We build to the drawings your designer takes through planning and give building control notice before each stage. The firm is run by its founder, who brings decades of hands-on building experience, and you get a written programme showing when the kitchen is out of action and when it is back.

• Aftercare and snagging support once the job is finished
• Old kitchen kept in use until the new shell is weathertight
• Boiler flue, soil pipe and gully moved off the rear wall in the right order

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.