04 / 04 House extension types
Kitchen Extensions
A kitchen extension adds new floor space at the back of your house. It turns a cramped kitchen into an open-plan kitchen diner where the family can cook, eat and spend time together, with doors out to the garden and light pouring in from above.
We are kitchen extension builders who handle the whole job as part of our house extensions service. That includes the foundations, steelwork, roof and glazing, the plumbing, electrics and the fitted kitchen itself.
- Part ofHouse Extensions
- Our process7 clear steps
- Answered here6 common questions
- FreeSurvey & itemised quote
01Which option
Kitchen Extension, Side Return or Renovation?
- Rear kitchen extension (this page): A single-storey extension across the back of the house. It adds depth and usually creates a kitchen diner.
- Side return extension: Fills the narrow side passage on a terrace to widen the kitchen.
- Wrap-around extension: A side return and rear extension together, for the largest open-plan space.
- Kitchen renovation: A new kitchen within the space you already have, with no extension needed.
02Design
Designing Your Kitchen Extension
- Layout: We plan the kitchen, dining and seating areas together, including the position of the sink, hob, island and appliances, before the structure is designed.
- Glazing: Bifold or sliding doors across the back, and rooflights or a roof lantern over the dining area.
- Roof: A flat roof with rooflights for a clean, modern look, or a pitched roof that matches the house.
- Islands: Services for an island sink or hob are laid in the floor before it is finished.
- Extraction: The cooker hood is ducted to the outside, planned into the walls or ceiling.
- Heating: underfloor heating installation keeps the walls free for units and suits large glazed areas.
03Planning
Do I Need Planning Permission for a Kitchen Extension?
Often not. A single-storey rear extension on a house in England is usually permitted development if:
- Depth: It extends no more than 3 metres from the original rear wall on terraced and semi-detached houses, or 4 metres on detached houses.
- Height: It is no more than 4 metres high, with eaves no higher than 3 metres within 2 metres of a boundary.
- Coverage: Together with other extensions and outbuildings, it covers no more than half the land around the original house.
- Materials: It looks similar to the existing house.
Deeper extensions, up to 6 metres or 8 metres, may be possible through the prior approval process. Under that process, the council asks your neighbours for their views before deciding. Planning permission is needed for flats and maisonettes, and extra controls apply to listed buildings, conservation areas and Article 4 areas. We check the route for your house and can apply for a Lawful Development Certificate.
04Building regulations
Do I Need Building Regulations for a Kitchen Extension?
Yes. Every kitchen extension needs building regulations approval, whether or not it needs planning permission. The main areas are:
- Foundations and structure: Foundations to suit the ground, and steel beams where the rear wall is opened up.
- Energy efficiency: Insulation and glazing to current standards. Large areas of glass must be balanced against insulation elsewhere.
- Ventilation: Extraction for cooking and background ventilation.
- Drainage: New drains for the sink and appliances, and rainwater from the roof.
- Fire safety: Smoke detection, and a safe escape route from the house.
- Electrics: New circuits certified under the wiring regulations.
If the extension is built over or within 3 metres of a public sewer, you will usually also need a build over agreement from the water company. We check the sewer records and survey the drains with a CCTV drain survey before the design is finished.
05Cost
What Affects the Cost of a Kitchen Extension in London?
Every extension is priced after a free survey, and you receive a written, itemised quote. The main factors are:
Every factor is priced line by line after your free survey — no guesswork, staged payments.
Book a free survey- 01
Size
The depth and width of the extension.
- 02
Glazing
Bifold or sliding doors, rooflights and roof lanterns.
- 03
Steelwork to open up the rear wall.
- 04
Foundations and drains, including any build over agreement.
- 05
The kitchen
Units, worktops, appliances and island.
- 06
Flooring and heating, including underfloor heating.
- 07
Access
Narrow side passages, or materials carried through the house.
- 08
Fees
Drawings, structural calculations, building control and any planning or party wall costs.
Timescale · 06
How Long Does a Kitchen Extension Take?
A single-storey kitchen extension is one of the quicker extension projects. The build time depends on the size, the glazing, the foundations and the lead time for the kitchen and doors. The new structure is built and made weathertight before the rear wall is opened up, so your existing kitchen can usually be used for much of the build. It will be out of use while the old kitchen is removed and the new one fitted, and we can help you plan a temporary kitchen. Your quote includes a programme for each stage.
One team · 07
One Team From Foundations to the Finished Kitchen
We coordinate every trade the kitchen needs:
- kitchen plumbing for the sink, dishwasher and washing machine
- gas hob installation by Gas Safe registered engineers, as the law requires
- domestic electrical installation for lighting, sockets and appliances
- kitchen and bathroom tiling for splashbacks and floors
- plastering and decorating
08Process
Our Kitchen Extension Process
Planned before we start, managed by one project manager, signed off at the end.
- 01
Free survey
We measure the house and garden, check the drains, boundaries and access, and talk through your kitchen layout.
- 02
Design and quote
Drawings, structural calculations and an itemised quote with a programme.
- 03
Approvals
A planning check, Lawful Development Certificate, prior approval or planning application, plus building regulations approval, party wall notices and any build over agreement.
- 04
Groundworks
Drains laid or rerouted, foundations dug and inspected.
- 05
Structure
Walls, roof and glazing built and made weathertight, then the rear wall opened up.
- 06
First fix and kitchen fitting
Wiring, plumbing and heating, plastering, then the kitchen, tiling and flooring.
- 07
Sign-off and handover
Building control completion, certificates and a final walk-round.
09Areas
Kitchen Extensions Across London
We build kitchen extensions across London, with a focus on east and south-east London. Find out more on our pages for kitchen extension in London, kitchen extension in Ilford, kitchen extension in Barking, kitchen extension in Dagenham, kitchen extension in East Ham and kitchen extension in Orpington.
10FAQs
Kitchen Extension FAQs
How much does a kitchen extension cost in London?
It depends mainly on the size, the glazing, the steelwork, the foundations and drains, and the kitchen you choose. We give you a fixed, itemised quote after a free survey, so you can see what each part costs.
Do I need planning permission for a kitchen extension?
Often not. A single-storey rear extension up to 3 metres deep (4 metres on a detached house) is usually permitted development. Deeper extensions may be possible through prior approval. Flats and conservation areas have extra controls.
How long does a kitchen extension take?
It is one of the quicker extension projects. The time depends on the size, the glazing and the kitchen lead times. Your quote includes a programme, and your existing kitchen can usually be used for much of the build.
Do I need building regulations for a kitchen extension?
Yes, always. Building control checks the foundations, structure, insulation, ventilation, drainage, fire safety and electrics, and issues a completion certificate at the end.
What is a build over agreement?
It is an agreement with the water company, usually needed if you build over or within 3 metres of a public sewer. We check the sewer records early, so it does not delay the build.
Can I supply my own kitchen?
Yes. We can build the extension and fit a kitchen you have bought, or arrange the whole kitchen for you. We coordinate the plumbing and electrics to suit your layout.
04House Extensions
Explore other house extension types
Next step
Book Your Free Survey
Tell us how you want your new kitchen to work. We will survey the house, check what your council allows and send you a written, itemised quote.
Send us photos of your kitchen and the back of your house on WhatsApp to get started, or use our contact form.
- Free survey
- Itemised written quote
- One project manager