Kitchen Extensions Marylebone

A kitchen extension in Marylebone starts with a hard fact about the stock: 92% of homes here are flats and 8% are houses, and the houses are terraced. That makes the rear of a Georgian townhouse the main place a new kitchen room can be built, often as a narrow addition at garden or lower ground level. For owners in mansion blocks, the kitchen grows inside the flat instead. Westminster City Council is the planning authority for both, and it runs its own building control service.

In Marylebone, 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 Marylebone: 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.

The rear of a Marylebone terraced house is where extensions go

In Marylebone a kitchen extension is a rear addition to a terraced house, because 8% of homes are terraced and none are semi-detached or detached. There is no side return to fill on a typical Georgian plot and no wraparound option, so the new room sits behind the house at garden or lower ground level. The width is set by the party walls on each side and by how much of the back elevation the designer leaves visible above it.

That shape drives the build. A long, narrow room needs its light from above, so the roof glazing and its position against the neighbours' windows matter more than the rear doors. The steel over the new opening in the back wall is sized by the structural engineer we appoint and often bears into the party walls. That is notifiable work under the Party Wall etc. Act, and you as building owner serve the notices on the neighbours. We sequence the steel, the roof and the kitchen fit-out in one programme.

Housing in Marylebone

The Council Tax list puts Marylebone at about 12,620 homes, 92% flats against 8% houses; 54% went up before 1919, 16% between the wars and 29% after 1945. Most homes here are flats, and only a ground floor flat in Marylebone with its own garden can extend its kitchen.

Why a Marylebone flat cannot simply add a kitchen room

A Marylebone flat has no householder permitted development rights, so any extension to it needs a full planning application. The national rules for extensions cover houses only, not flats and maisonettes, and 92% of the homes here are flats. The garden flat on the lower floor of a converted townhouse is the one flat that can sometimes build outward, and then only with planning permission and, under most leases, the freeholder's written consent.

For everyone else in Marylebone, the extra kitchen space comes from inside the lease line. That usually means joining the kitchen to the reception room, moving it into a larger room, or rearranging the hall. Each of those normally needs a licence to alter from the freeholder under the lease, and taking out a structural wall needs steel sized by the structural engineer we appoint. We plan the opening, the new services and the kitchen units as one job, so the managing agent sees one start date and one finish date.

Where the national size limits stop applying in Marylebone

The national limits are a starting point in Marylebone, not the answer. A single-storey rear extension on a terraced house can go three metres past the original back wall without an application, subject to the other conditions, or six metres with prior approval, and no higher than four metres. The larger prior approval route is not available on Article 2(3) designated land, which includes conservation areas, and any side extension there needs householder planning permission.

East Marylebone has been a conservation area since 1982, with its boundary widened in 1990. Westminster's guidance for its conservation areas says an extension must respect the scale of the house and be architecturally subordinate to it, and full width rear extensions are generally not acceptable except in some cases at basement level. So your designer is likely to draw a part-width room, and we programme around the planning decision date and order steel only once consent is issued.

Building control for the kitchen and the lower ground floor in Marylebone

Westminster runs its own building control service, and if you use it rather than a registered building control approver, a new kitchen room in Marylebone goes in as full plans. The council allows a building notice only where the work leaves the layout of the building unchanged and falls outside the Fire Safety Order, and an extension changes the layout. Full plans also give the structural engineer's calculations a formal check before the steel arrives on site.

Many Marylebone kitchens sit on a lower ground floor, and owners often ask about digging down for ceiling height. Digging that floor down is likely to count as basement development, and Westminster has taken away the permitted development rights for basements across the whole city, so expect to need planning permission. If you want both, the kitchen plan and the basement drawings are prepared together, and we build the slab, the drainage and the units in that order.

• Flat roofs with rooflights or a roof lantern over the kitchen
• Soil stack and gully rerouting beneath the new floor
• Floor levels matched through the old opening

VOA Council Tax stock of properties, March 2025, for Marylebone & Park Lane and Bryanston & Dorset Square. Counts rounded by the VOA.

Alongside kitchen extensions in Marylebone, the pages that usually help next are kitchen renovation in Marylebone, kitchen extensions across Westminster, a wraparound kitchen-diner, how building control inspects an extension, our London kitchen extensions page and Steel-Framed Doors Guide.

Why Marylebone Homeowners Choose GS Renovation

You get one team for the structural opening, the drainage, the roof glazing and the kitchen itself, run as a single programme so no trade waits on another. We build to your approved drawings and to the steel sized by the structural engineer we appoint. We give the managing agent or your neighbours a clear sequence and working hours before work starts, and we keep the inspection records and trade certificates together, ready for your completion certificate.

• Drains surveyed by camera before the footprint is fixed
• Building control and Part P certificates handed over together at the end
• Founder with 30+ years of hands-on experience

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.