Kitchen Extensions New Barnet

A kitchen extension in New Barnet depends on which half of the stock you live in. Half the homes here are houses and half are flats, and the houses are interwar semis, post-war houses and some Victorian terraces. A semi suits a rear or wraparound kitchen, a terrace suits a side return, and a flat has no householder permitted development at all. We build the shell, the steel, the drainage and the fitted kitchen as one programme.

In New Barnet, 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 New Barnet: 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.

Rear, wraparound or side return on a New Barnet house

The shape of the extension follows the house type, and in New Barnet semi-detached and detached houses make up 32% of homes against 15% for terraced houses. On a semi the gain is across the full back wall, and it can turn the corner into the side passage so the kitchen becomes an L with a dining end. That corner needs a post or a longer beam where the two new walls meet the old ones, and the structural engineer we appoint decides which before the kitchen is drawn.

A terrace gains its width from the side return, the strip beside the back addition. The new roof runs up to the boundary, so the gutter detail and the neighbour's wall come into the design early, and the Party Wall Act may apply, with notice served by you as building owner. The openings are in the flank of the outrigger and often the back of the main house too. Either way the downstand or flush beam fixes where the wall units and the island can sit, so we settle the steel before the kitchen plan is signed.

Housing in New Barnet

Take the 10,670 or so homes the valuation list gives the New Barnet and Hadley Wood statistical areas: 50% flats, 50% houses, 17% from before 1919, 32% interwar and 52% post-war. Where many homes are flats, a kitchen extension to a flat in New Barnet is possible only on the ground floor, with a garden of its own, planning permission and the freeholder's written consent.

How far a New Barnet kitchen can go without a planning application

Permitted development allows a single-storey rear extension up to three metres beyond the original rear wall of a semi or terrace, and four metres on a detached house. It also caps the height at four metres, which matters when you want a pitched glass roof or a raised lantern over the island. The depth is measured from the original house, so a conservatory or utility added by a past owner counts towards it.

Through the prior approval route, and outside designated land, the rear limit rises to six metres for a semi or terrace and eight metres for a detached house. Neighbours are notified and can comment, so the timing goes into the programme before any groundwork. Your designer or agent makes the submission; we build to what comes back and give them the construction details they need to describe the job accurately.

Side additions, designated land and ground floor flats

A wraparound adds a side element, and on Article 2(3) designated land such as a conservation area every side extension needs householder planning permission. The national Planning Data service lists 16 conservation areas for Barnet, so the first check on any New Barnet address is whether it falls inside one. If it does, the side part of the kitchen cannot start until a planning decision is in, which also means the drawings have to be ready earlier.

Half of New Barnet's homes are flats, and a ground floor flat with a garden is in a different position from a house. Householder permitted development rules apply to houses only, so a flat needs planning permission for any extension, and the lease will almost always require the freeholder's written consent too. The kitchen itself can often be reworked inside the flat first, with the extension drawn so it can follow once both consents are in hand and the lease terms are clear.

Solid floors, drainage and glazing in post-war New Barnet houses

52% of New Barnet's homes were built after 1945, and post-war houses commonly sit on a solid concrete ground floor. Joining a new slab to an old one means matching levels, lapping the damp proof membrane and deciding where underfloor heating pipes cross the line of the old back wall. Interwar homes, a further 32% of the stock, are more likely to have suspended timber floors, where the air bricks must be kept vented once the extension covers them.

The sink usually moves to an island or the new back wall, so the waste has to reach the existing run with a proper fall. If a public sewer crosses the garden, a build over agreement with the water company goes into the programme. Roof lights and sliding doors are ordered from the approved drawings early, because their lead times often set when the shell can be closed and the kitchen fitters start.

• Flat roofs with rooflights or a roof lantern over the kitchen
• Wet underfloor heating laid in the new screed
• New kitchen circuits, with Part P certification from a registered electrician

VOA Council Tax stock of properties, March 2025, for the New Barnet and Hadley Wood statistical areas, which also take in East Barnet and Hadley Wood. Counts rounded by the VOA.

Related reading for New Barnet homeowners planning kitchen extensions: kitchen renovation in New Barnet, kitchen extensions across Barnet, fitting the kitchen itself, the Party Wall Act on a boundary build, our London kitchen extensions page and Renovating a 1930s Semi.

Why New Barnet Homeowners Choose GS Renovation

We run the whole kitchen extension under one programme: groundwork, steel to the structural engineer's calculations, drainage, roof, glazing, then the plastering, electrics by a registered electrician, and the kitchen fit itself. You deal with one site manager rather than splitting the job between a builder and a separate kitchen company. We work to the drawings your designer produces and to building control inspections, and we tell you at quotation which parts of your New Barnet house affect the steel and the drainage.

• Site left safe and secure at the end of every day
• Cooker extract taken outside through the new roof or flank wall, not recirculated
• 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.