From the design through to planning; from costs to the trades you employ — there are lots of things to consider if you’re taking on a kitchen extension.

A well-executed kitchen extension will not only transform how you live in your home by creating a hub where you eat, relax and entertain, but can also add real wow-factor, too.

Here’s what you need to know to build a successful kitchen extension, whatever its size or shape.

How Much Does a Kitchen Extension Cost?

Getting to grips with how much your kitchen extension might set you back is one of the first things you need to know to establish what your budget will get you.

In general, a single storey kitchen extension is likely to be £1,000-£2,000/m², giving a typical cost of £25,000-£50,000 for a footprint of around 25m². The total cost of the project, however, will depend largely on the specification of the kitchen itself, with kitchens varying dramatically in price depending on the choice of supplier, the materials used and the appliances specified.

knocking through kitchen extension

The homeowners of this cottage removed walls to create a bigger kitchen-dining-living space

Get an idea of your costs with our free Extension Cost Calculator

Do I Need Planning Permission for a Kitchen Extension?

If you are going to be adding a kitchen extension to create your new multi functional space, then you may be covered under Permitted Development (PD) rights and therefore not require planning consent.

However, bear in mind that if your house is in a Conservation Area or national park, the amount of work you can do under PD is usually reduced.

To be covered under Permitted Development rights, a single-storey extension should:

  • be a maximum height of four metres
  • not extend beyond the original rear wall of the house by more than six metres if it is an attached house (i.e. semi-detached), or eight metres for a detached home
  • If you are adding a side extension, this must be single-storey with a width of no more than half that of the original house.

If Your Building is Listed…

Then you will require planning permission regardless of whether you are adding an extension or knocking through a wall. If you have any doubts, you should check with your local planning department.

What Kind of Kitchen Extension Should I Add?

How you extend will largely depend on your budget and the space that’s available. If you have a terraced or semi-detached home with a kitchen to the rear, adding a small rear extension for an open-plan kitchen diner leading out to the garden could be the best solution.

If you have restricted garden space, then a small side-return kitchen extension could provide you with useful extra space.

Where budget and outside space allows, consider a large rear kitchen extension spanning the width of the house, incorporating an open-plan kitchen, dining and living space.

clad kitchen extension

This contemporary extension features aluminium bifold doors, slim aluminium window and a frameless rooflight from IQ Glass. The brick and wood cladding tie the extension in with the materials used on the original house

Building Regulations for a Kitchen Extension

Your work will require Building Regulations approval to ensure that the minimum design and construction standards are achieved. These cover all manner of subjects such as fire and other forms of safety, insulation, drainage, electricity and access.

The role of a Building Control officer is to ensure that the minimum standards set out by the Building Regulations have been met. If you are carrying out a kitchen extension, Building Control will need to be notified.

Send a Full Plans application to the local authority, where you pay a fee and the building inspector visits the site at the various stages of the build and inspects the work as it proceeds.

Planning the Layout of Your Kitchen Extension

When planning the layout of your kitchen extension, you will need to keep in mind the basics of what each kitchen requires (fridge freezer, cooker, sink) and then add features around these items.

If you are looking to create a multifunctional space with your kitchen extension, such as an open plan kitchen-diner-living room, zoning the cooking and eating areas will be important. This can be done using furniture and storage.

A kitchen island between the work station units and the dining table, for instance, is a perfect break between the separate spaces, and is also a place where you can store pots and pans, and even install a hob and second sink. A breakfast bar can also serve as a way of zoning the kitchen from the dining area.

Remember, however, to leave enough space to move around; giving at least one metre between worktops.

Units will need considering too, and your choice will depend on how you will be using the space and the style you are going for.

For instance:

  • Do you want appliances on show or built-in?
  • Will you be storing dried goods in cupboards or will they be sited in a separate pantry, or indeed the freezer?
  • Do you have a lot of crockery that needs a home?
  • Do you own a lot of deep pans which will need equally deep drawers or shelves?
  • Will you require multipurpose worktops that house built-in knife racks or pull-out electrical sockets?

All of these questions will need answering from the outset so you can ensure your kitchen design meets your requirements.

open-plan kitchen extension

The homeowners of this four-bed home created a large open-plan kitchen diner with a kitchen extension that now links the outside in. Image: William Goddard

How Long Will a Kitchen Extension Take?

Project time depends largely on whether you will be extending the property, the type of interior fit-out, and specifications you choose. A single storey kitchen extension, for example, will on average take 12 weeks, however if you are specifying underfloor heating this will add to the time.

open plan kitchen extension

The skylight, lighting and zones help to create a family-friendly kitchen diner space. Image: Rational

Bringing Natural Light into a Kitchen Extension

Big or small, kitchen extensions give you the opportunity to create a light-filled space, so don’t forget to think about windows and doors to help lighten and brighten the room and connect the inside out. 

One of the benefits of having an open-plan kitchen space where you dine and relax is that you are not sacrificing natural light by having smaller separate rooms.

If your kitchen extension is to the rear of the property, consider bifold doors that open to the garden.The full-height glazing will allow in plenty of sunlight as well as offering views of the outside.

If you are choosing to add a side-return extension or are after more privacy, then opting for clerestory windows is a good design solution. A bank of rooflights is another popular option as light then penetrates deeper into the space.

Choosing the Right Artificial Lighting For a Kitchen Extension

Include a lighting scheme which is practical but also brings the wow-factor in the evenings.

  • Under cupboard lights, sometimes controlled by dimmable switches, are a favourite for offering a soft glow to worktops
  • Spotlights on the ceiling can offer a brighter, white light suitable for areas such as work stations where you’ll want good visibility
  • Pendant lights can be hung over the dining table, but look great in a row over a kitchen island, too
Kitchen extension lighting

Drop-pendant lighting has been used effectively to highlight the kitchen space. Image: Original BTC

Who Do I Need to Build My Kitchen Extension?

Chances are that your kitchen extension will demand some form of structural work and you will need to enlist the services of a designer as well as builders. Once you have chosen a designer, they will draw up plans for the project (to be submitted to the local planning department if your project is going to require approval), and to provide the builders with during the tender process.

When selecting builders to carry out the work:

  • Make sure they come recommended and ask to see previous projects and speak to previous clients for peace of mind.
  • Try to avoid paying day rates.
  • Agree on a fixed price where possible.

You may, however, wish to go down the route of employing a design and build extension company who will be able to handle everything from the design through to the building works and fit-out.

kitchen extension_shaker designThis kitchen by Brayer Design features an island unit that doubles as a prepping and cooking area with sociable seating

Bringing Electrics and Plumbing Services into a Kitchen Extension

You do need to make sure that your current electrics and plumbing services are adequate enough to cope with extra load in your kitchen extension.

  • Electrics: Your electrician will need to check the existing system to see whether rewiring is necessary. They will then return to carry out second fix electrics – such as connections to plug sockets – before the worktops are fitted.
  • You will need to call in a plumber to check the existing pipework is in good condition. You will need to ensure you have both a hot and cold water supply, as well as a waste pump from the sink to the outside. Appliances, such as your washing machine and dishwasher, will also need to be connected to the water supply.
Kitchen extension - blinds

A kitchen extension gives you the chance to include lots of windows to let in as much light as possible but if privacy is an issue, factor in blinds, like these roller blinds from English Blinds

How Will I Heat my Kitchen Extension?

Radiators are a cheap way to heat the kitchen diner, however plinth heaters are a good choice if you are limited on wall space as they fit neatly between the bottom of the base units and the floor. Heated towel rails – complete with pegs for tea towels – are also popular.

At the higher end of the scale is underfloor heating (UFH) which, while more expensive and more hassle to install, is perfect for providing even and comfortable heat on kitchen floor types (such as stone or tiles) which are prone to feeling cold. UFH will, however, require the removal of floorboards and existing tiles — adding to both time and costs.

Choosing the Right Kitchen Appliances

Looking to update your kitchen appliances? Take a look at these best buys from

View these kitchen diner projects for inspiration

Main header image: AR Design


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