How to plan a kitchen extension

Confused about where to start with your kitchen extension project? From budgeting to planning permission, this article will tell you all you need to know

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Planning your kitchen extension properly is an essential step in creating the home of your dreams, without having to move. It is the perfect opportunity to decide how your lifestyle could be improved with a simple change of layout, the introduction of natural light and the addition of appliances that could make your life easier.

Follow the steps below to make sure your kitchen extension is planned properly. Want advice on how to get the right look for your project? Check out our expert advice for designing your kitchen extension. Find out, too, how to cost your kitchen extension.


Related articles:  12 Kitchen extension ideas under 100k | The ultimate guide to extending your home

1. Decide what your kitchen extension needs

Is it important for your new kitchen extension to have a spacious cooking and prep area, or to offer a combination of separate dining, relaxing and entertaining functions? Write a list of all the features that you already have in your kitchen, then add the features and appliances that you wish to add to the space.

Kitchen extension essentials:

  • Kitchen as proportion of extension
  • Island unit
  • Breakfast bar
  • Dining area as proportion of extension 
  • Seating area as proportion of extension 
  • Walk-in larder
  • American-style fridge-freezer
  • Range cooker
  • Washing machine
  • Dryer
  • Separate utility room
  • Store room
  • Bi-fold doors
  • Outdoor dining area immediately outside

2. Figure out your kitchen extension budget

With plans in place, you can work out how much you can afford to spend on each element of your kitchen extension, and make alterations to plans if your budget won’t allow for certain design elements.

Prices will vary depending on the work you carry out, but as a guide:

  • Plan for between £1,200 – £3,000 per m² and up for building work
  • £17 – £200 per m² for a new kitchen
  • Painting a tiling the walls will cost between £50 – £100 per m² if you use a contractor
  • Flooring will cost between £25 – £100 per m²

For a more in-depth exploration of kitchen extension costs, check out our dedicated feature. Alternatively, use our free extension cost calculator to get an idea of how much your project is likely to cost.

Building regulation costs depend on:

  • What work is involved in the extension
  • The over all area of the proposed project

3. Decide where to place the kitchen extension

If you’re looking to create an additional space for a large, open-plan family kitchen, the first step is to assess which area of your home will benefit the most from an extension. You should explore all available options to extend and remodel, which may include knocking down internal walls and reconfiguring the existing layout, or converting a garage or utility space to change its function.

‘As one of the principal spaces in your home, the kitchen should ideally be accessible from the main hallway and not through another room,’ says property expert Michael Holmes. ‘Typically, extensions are added to the side or rear of a property to maximise links with the garden as well as create extra space internally. In a townhouse, you may find it makes sense to convert/extend the cellar to form a lower-ground-floor basement storey, ideally with a light well that will introduce natural light into the space.’

Once you’re decided where you’d like your extension to be located, consult a RIBA-registered architect to find out what can be achieved.

4. Find a good architect

You will need plans and construction drawings for the builder, and to show compliance with building regulations. Work with an architect or architectural technologist to provide these. ‘They can also inspire you with design solutions that you may not have considered,’ says Hugo Tugman, founder of Architect Your Home. 'Hire someone who specialises in homeowner projects and get them to do a small amount of paid-for work, such as a sketch design, to see if they are the right person for the job.’

Decide how much involvement you want them to have. ‘Some only offer a full service, also overseeing construction,’ says Alan Cronshaw of Acronym Architecture & Design. ‘Others offer a partial service, ending ties after planning and building control approval are gained.’ 

Find an architect at or an architectural technologist at

5. Spend time on the brief

Let your designer know what you want. ‘A common mistake is to brief your architect with a set of constraints without talking through the possibilities,’ explains Hugo. ‘When I work with a homeowner, I discuss the brief and sketch designs around their kitchen table, to involve them and ensure that what I am creating fits their needs and lifestyle.’

6. Apply for planning permission

If the work is classed as permitted development, you won’t need to apply for planning permission, but you may wish to apply for a certificate of lawful development, which proves the project is legal. If you do need planning permission, you will have to apply to the local council, and may need additional reports. Whichever route you are taking, you will need building regulations approval. It may be necessary to issue a party wall notice if you are building on or close to the boundary with a neighbour.

7. Put the kitchen extension out to tender

With the plans in place, you can go ahead and find reliable building contractors to tender for your extension work. Consider personal and professional recommendations, as well as through trade bodies such as the FMB (Federation of Master Builders).

Arrange to meet at least three contractors and, to obtain estimates, send them the plans, construction drawings and specification documents, plus the contract you want to use, so they can quote as accurately as possible.


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