Hampstead Architecture and Planning

Extensions & Renovations

Kitchen Extension Architects in London

The kitchen extension is the heart of most family-home projects: a bright kitchen-dining-living space that opens to the garden. We design these spaces as architecture and joinery together, coordinating layout, light, ventilation and the connection to the garden.

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Practice leadership

Eyal Moran, Director and Lead Architect, is an ARB-registered architect, leading design judgement, planning strategy and technical coordination across client projects.

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The short answer

Do I need planning permission for a kitchen extension?

Not always. A single-storey rear or side kitchen extension can sometimes proceed under permitted development, but that right is removed for flats, listed buildings and much of conservation-area London. Where a householder application is needed, the council typically decides in about eight weeks. We confirm the route for your property before design begins.

The heart of the home

A kitchen extension is rarely just about the kitchen. It is about how cooking, eating, relaxing and the garden come together in one well-lit space, and how the joinery, island, storage and seating are arranged within it. The difference between a good kitchen extension and a great one is usually invisible on a plan — it is in the sightlines, the light at the time of day you use the room, and whether the everyday journeys around it feel effortless. We design the architecture and the kitchen as one, so the result is coherent rather than a kitchen dropped into a box.

Designing the room around how you live in it

We start from how the space will actually be used: where you cook, eat and sit, where the children do homework while dinner is made, and how the room connects to the rest of the house and the garden. That drives the zoning — the working kitchen, the island as a social hub, a dining area, somewhere soft to sit — and the practical support spaces a busy kitchen needs, such as a pantry or a utility room to keep noise and clutter out of the main room. Getting this layout right at design stage is what makes a kitchen extension feel generous rather than merely large.

The services that make a kitchen work

A kitchen is the most service-heavy room in a house, and these have to be planned, not retrofitted. Extraction is the big one — a recirculating hood is simple but a ducted extract to outside performs far better and needs a duct route resolved through the new roof or wall. Add the drainage and water for the sink and dishwasher, the gas or electric supply for the hob, underfloor heating zoned to the space, layered lighting for cooking and for evenings, and background ventilation under Approved Document F. We coordinate all of this into the building regulations drawings so the room works on day one.

Glass, light and not overheating

Kitchen extensions love glass — roof lanterns, rooflights and sliding doors to the garden — but glazing that is wonderful in spring can bake the room in July. We balance the openings with the orientation, specify glass with the right solar control, and design shading and ventilation so the space stays comfortable without blinds permanently down. We also detail the threshold to the garden for level, step-free access and a floor finish that can read as continuous inside and out, which is what makes a kitchen genuinely open to the garden rather than just facing it.

Working with your kitchen supplier

Most clients buy their kitchen from a specialist supplier, and the project succeeds or fails on how well that design and the architecture are coordinated. We set out the space, the services and the appliance positions, and work alongside your kitchen company so the cabinetry, the island, the extraction and the power and water all land where they should — resolved before plastering, not discovered afterwards. The result is an installed kitchen that fits the room as designed, with none of the classic clashes between builder, designer and supplier.

Opening up to one room: the structural decision

Most kitchen extensions are only half a new box; the other half is knocking the existing rear wall through so the old kitchen and the new space read as a single room. That existing wall is usually load-bearing, so removing it means a beam — typically a steel — carrying the floor and wall above, designed and calculated by a structural engineer. The decision that shapes the room is whether that beam sits below the ceiling as a downstand or is hidden flush within the floor build-up above. A downstand is cheaper but leaves a visible line where old meets new; a flush beam keeps the ceiling continuous so the space genuinely feels like one room, but asks more of the structure and the budget. Where the opening is wide, a goalpost frame with posts at each side may be needed, and temporary support has to hold the house up while the wall comes out. We resolve the beam type and the ceiling line at design stage, because it is far harder and more expensive to change once the steel is in.

Comparing builder quotes without comparing apples with pears

A kitchen extension is where owners most often receive builder quotes that look wildly different, and the gap is almost always in what each one has assumed rather than in the price of the work. If one builder has priced a ducted extractor, underfloor heating, rooflights and a resin floor while another has allowed for a recirculating hood, radiators and standard tiles, the cheaper number is not better value — it is a different project. The way to get comparable quotes is to price them all against the same drawings and specification, with the kitchen units, worktops and appliances carried as a clearly stated provisional sum so the builder is not guessing what you will choose. That single figure is usually the largest variable, and leaving it vague is how budgets drift once work has started. Our building regulations drawings and specification give every builder the same basis to price against, so the numbers you compare are genuinely like-for-like and the tender reflects the room you actually want, not four different interpretations of it.

What we produce

Typical deliverables

  • Kitchen-dining-living layout design
  • Planning drawings where required
  • Joinery and island coordination
  • Lighting and ventilation strategy
  • Building regulations drawings
  • Structural engineer coordination

London-specific

What to keep in mind

  • Glazed extensions need overheating and shading consideration
  • Extractor and drainage routing affects the design
  • Conservation areas may restrict rooflights and materials
  • Party wall and drainage issues on boundary work

How the process works

From first call to completion

  1. Brief

    We understand how you cook, eat and live.

  2. Design

    We develop the space and kitchen layout together.

  3. Planning

    We prepare any application required.

  4. Technical

    We resolve services, ventilation and structure.

  5. Build support

    We coordinate with the builder and kitchen supplier.

Considering this for your property?

Tell us the address and a short description of the work. We will advise which drawings, approvals and consultant inputs your project is likely to need.

Avoiding pitfalls

Common risks & mistakes

  • Designing the extension before the kitchen layout
  • Forgetting extractor and ventilation routing
  • Over-glazing without managing summer overheating
  • Mismatched floor levels to the garden

Frequently asked questions

Do you design the kitchen as well as the extension?

We design the architecture and the kitchen layout together and coordinate with your kitchen supplier, so the space and the installed kitchen work as one.

How do you stop a glazed kitchen overheating?

Through orientation, glazing specification, shading and ventilation strategy, designed in from the start rather than fixed afterwards.

Will a kitchen extension need planning permission?

It depends on the property and the works. Conservation areas, flats and listing often require permission. We assess your property.

Can the floor flow into the garden?

Yes, with careful level and threshold detailing and the right finishes, we can create a continuous indoor-outdoor floor.

What about ventilation and extraction?

These are designed in early, including extractor routing and background ventilation, and coordinated with the building regulations information.

How much does a kitchen extension design cost?

We work to fixed fees agreed in writing before each stage, not open-ended hourly rates, scaled to the size and complexity of your scheme. The simplest way to start is our £395 route review, which confirms the right drawings and application route and is credited in full against your project if you proceed. The fixed-fee drawing packages and what each includes are published on our packages page, and a fuller design service for a larger kitchen extension is quoted after we have reviewed the property and brief.

How long does a kitchen extension take from brief to build-ready drawings?

Two things run in parallel on a kitchen extension, and the programme is set by whichever finishes last. The first is consent: where a householder application is needed the council's statutory target is about eight weeks from validation, and where the works are permitted development that clock does not apply, though building control still does. The second is the room itself. The layout has to be settled early, because the extract route, the drainage, the power and the position of the island all follow from it, and those decisions are carried into the building regulations drawings rather than resolved on site. The variable owners underestimate is the kitchen supplier — cabinetry design and appliance lead times sit on the supplier's calendar, not ours, which is why we fold them into the sequence during design rather than discovering them at plastering.

Discuss your project

Tell us about the property, location and the work you are considering. We will advise which architectural drawings, approvals or consultant inputs are likely to be needed.

Areas

Kitchen Extension Architects across London

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North London

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Central London

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West & South West London

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East & South East London

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East & South East London

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