Kitchen extensions are becoming increasingly popular as homeowners look to create open-plan kitchen diners that become the ultimate sociable space. Plus, they can add value to a property so can be a great investment. But how much do they cost? We explain everything in this guide.

How much does a kitchen extension cost?

Kitchen extension costs in the UK can range from £20,000 to as much as £200,000. How much you’ll spend depends on various factors, including the type of extension you choose, the size, the complexity of the design and where you live, but here are some average costs to expect:

Type of kitchen extension	Average cost
Side return extension (30m2)	£68,000
Rear extension (30m2)	£64,000
Wraparound extension (45m2)	£101,850

These prices are excluding VAT and are averages for the whole country. At HaMuch, we use our database of hourly and daily rates to help you estimate kitchen extension costs for your area. Take a look at the table further down the page to get an idea of how much a kitchen extension will cost in your nearest town or city.

Kitchen extension cost per m²

The cost per square metre for a kitchen extension typically ranges from £1,500 to £3,000 or more, depending on factors such as the complexity of the design, quality of materials and your location. Basic extensions with standard finishes may fall towards the lower end of the cost spectrum, while more extensive projects or those involving premium materials and bespoke features may command higher prices.

What affects the cost of a kitchen extension?

There are several factors that can affect the cost of a kitchen extension:

• Size: As you’d expect, the bigger the extension, the more it will cost. However, you may find that the cost per m2 goes down on larger extensions.

• Complexity: The more complex your design, the more expensive your kitchen extension will be.

• Choice of materials and finishes: If you choose high-end fixtures and finishes, you’ll pay more than if you choose budget materials. However, premium materials may increase the value of your property more than lower-end materials.

• Structural alterations and reinforcements: If you’re removing load bearing walls, you’ll need to factor in the cost of reinforcements such as RSJs. It’s important not to cut corners on structural reinforcements as they are what keeps your property stable.

• Planning permission: Many kitchen extensions will fall under permitted development, so you won’t need to apply for planning permission. But if you do, the average application costs £300.

• Additional features and amenities: If you want to add extra or more premium features to your kitchen extension, like skylights or bifold doors, expect to pay more. Adding extra amenities like downstairs toilets will also increase the cost as you’ll need new plumbing.

• Your location: Labour and material costs vary across the country. If you live in London or the south east, you’ll pay more than those living in other areas.

Types of kitchen extension

The type of kitchen extension that’s right for you will depend on your budget, your type of property and how much additional space you want. Your builder will be able to advise on the best type of kitchen extension for your property:

Side return

Side return extensions are ideal for terraced properties with unused space at the side. While they’re often only small extensions, they can help add a huge amount of space to your kitchen for a relatively low cost compared with other extension types.

Side return extensions are ideal for adding more light to your kitchen with skylights and bifold or sliding doors. They also have the benefit of not eating into your garden, which is ideal if your garden space is already limited.

Rear

Rear extensions are perfect if you don’t have space for a side return or you want to add more space than a side return extension would allow. However, they obviously extend into your garden, so consider how much of your garden you’re willing to lose.

Rear extensions are ideal if you want to add a lot of extra space for a kitchen diner or fully open-plan living area. They can also create a great blend of the inside and outside with big bifold doors.

Wraparound

Get the best of both worlds with a wraparound kitchen extension that combines a side and rear extension. You can add much more space with a wraparound extension, creating a dream kitchen diner that becomes the hub of the home.

How long does it take to do a kitchen extension?

How long it takes to complete a kitchen extension depends on its size, complexity, the weather conditions and availability of materials and labour.

On average, a basic side return kitchen extension may take around 2 to 3 months to complete, while larger or more intricate projects like wraparound extensions may take 6 months or more.

Does a kitchen extension add value?

Yes, a well-designed and professionally executed kitchen extension can significantly increase the value of your property. By expanding living space, enhancing functionality and improving the look of your home, a kitchen extension appeals to potential buyers and commands a higher resale value.

However, it’s always best to consider a kitchen extension as a lifestyle choice as opposed to a pure investment, as you may not always get your money back. But even if you don’t make money on your kitchen extension, it’s still more likely to attract buyers and help you sell your home quicker.

How to do a kitchen extension on a budget

If you know you need the extra space but don’t have a huge budget for your kitchen extension, there are a few things you can do to get a great kitchen extension on a budget:

• Avoid planning permission: Only extend as much as you are allowed under permitted development rights so you don’t have to pay for planning permission.

• Keep it simple: Keep your design simple to keep building and material costs down.

• Use standard fittings and affordable brands: Stick to standard-size door and window frames to avoid bespoke or custom-made products, and use well-known but mid-range brands for your fixtures.

• Keep your neighbours on side: Party wall surveyors can cost thousands to draw up if your neighbours object to your plans. Keep your neighbours in the loop by showing them your drawings early, so when you notify them officially they don’t object.

• Manage the project yourself: Some people prefer to use an architect to draw up the plans for their kitchen extension and then manage the project from start to finish. This could cost up to 25% of the build cost, so if you have a simple extension design you may be able to draw up plans with your builder then manage the project yourself.

Can I extend my kitchen without planning permission?

Yes, in many cases, you can extend your kitchen without planning permission. You just need to ensure that your extension meets the requirements for permitted development. For your extension to be considered permitted development, you’ll have to meet the following conditions:

• The property hasn’t been extended since 1^st July 1948

• Your property isn’t in a conservation area

• It’s a house, not a flat

There are also rules for permitted development, including:

• The extension can’t use more than half the land surrounding the original building

• The extension can’t be taller than the tallest part of the original building

• The height of the eaves can’t exceed 3 metres once the extension comes within 2 metres of a boundary

If you’re unsure about whether your kitchen extension can be built under permitted development rights, make sure you speak to your local authority before going ahead. If you build an extension without planning permission, they can fine you or even force you to tear it down.

Do I need an architect for a kitchen extension?

While you don’t legally need an architect for a kitchen extension, it’s often a good idea to use one. Architects bring expertise in design, planning regulations and structural considerations, ensuring your extension meets building regulations and maximises space effectively.

To save money on an architect, you could engage them only for drawing up the plans. Architects usually charge between 5-12% of the construction cost for this, so it’s cheaper than using them to manage the whole project.

That being said, if you are planning a small or simple extension, you may be able to draw up plans with your builder to save money.

Can I build on top of my kitchen extension?

Yes, it's possible to build on top of your existing kitchen extension, which is known as a double or two storey extension. Before you go ahead, you’ll need to check that the foundations are adequate to withstand an additional floor. Make sure you have structural assessments done and speak to an architect to determine whether it’s feasible to build on top of your kitchen extension.

If you’re ready to compare quotes for your kitchen extension, post your job on HaMuch now. We’ll send it to extension builders in your area who will be happy to help.

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