Kitchen Extension Cost

By Kim
Last updated 12th July 2023 - Reading time: 0 mins
At a glance
  • The average cost of a kitchen extension is around £30,000
  • The job will approximately take between 5 - 10 weeks to complete
In this article, you'll find out the following:
  • A breakdown of pricing information including types of kitchen extensions and everything that's involved in such a task
  • How long the job may take and a general overview of what types of jobs can be performed
  • How to find and hire a kitchen installer

Are you considering having a kitchen extension built and want to know the costs?

Well, the average cost of a kitchen extension is between £25,000-£35,000.

But what can affect the overall costs?

There are many different options and types when it comes to building a kitchen extension. With this in mind, the price for a kitchen extension can vary greatly.

In this complete guide we cover all types of kitchen extensions such as rear kitchen extensions, kitchen diner extensions, open plan kitchen extensions, a small kitchen extension and more!

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Read on to find out how much a kitchen extension will cost you exactly...

Kitchen extension guide

Average Cost of Building a Kitchen Extension:

Depending on the complexity of the job, it usually takes: 5-10 weeks


How Much Are Kitchen Extensions?

Your location can affect the cost of a kitchen extension as well as the complexity of the job. The size of the extension, the finishes, the flooring, and the kitchen type can also affect the overall cost.

The average cost for a kitchen extension is around £25,000-£35,000. In London, this price could be closer to £40,000-£55,000.

Kitchen extension prices

You will need to think about the original demolition costs, the build itself, and the new kitchen.

The build quality is important too, for example:

  • A straightforward kitchen build will usually cost around £1320-£1620 per m2
  • A good quality build would be around £1700-£2000 per m2
  • an excellent quality build will cost around £1800-£2500 per m2

There are many variations when it comes to building a kitchen extension. A small, basic kitchen extension could cost as little as £12,000. A larger extension with top-quality kitchen fittings could cost in excess of £100,000.

If you need some inspiration, check out our complete kitchen ideas guide!

I am based in Wales and I’d like to have a wall knocked down and my kitchen extended. What sort of costs can I expect to face if I approach kitchen fitters in my area to perform this work? I’d like to have the new kitchen be of mid-quality.

"hello, A mid range kitchen for a good supplier for an average size kitchen would be in the area of £4000 and probably £600 to fit it. as for knocking the wall down then will depend on the opening and how much weight is above I.e single story or more as this determine the steel size. as a guess with no sizes there could be another £1000"

Kitchen Extension Prices

Below is a table highlighting the costs for different types of kitchen extensions based on their size and finish:

Extension Type Average Cost
Basic Kitchen Extension – Small (15m2) £12,000-£16,000
Basic Kitchen Extension – Medium (24m2) £19,000-£26,000
Basic Kitchen Extension – Large (48m2) £38,000-£52,000
Average Kitchen Extension - Small (15m2) £19,000-£26,000
Average Kitchen Extension - Medium (24m2) £26,000-£34,000
Average Kitchen Extension - Large (48m2) £52,000-£67,000
Deluxe Kitchen Extension - Small (15m2) £21,000-£30,000
Deluxe Kitchen Extension - Medium (24m2) £34,000-£48,000
Deluxe Kitchen Extension - Large (48m2) £67,000-£100,000
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Supply Only Costs

Below is a table highlighting the supply costs of a kitchen extension. This indicates all of the costs that may come up without the cost of labour:

Type of Supplies Average Cost
Basic Kitchen Units £3000-£5800
Average Kitchen Units £4300-£7600
Deluxe Kitchen Units £5100-£10300
Basic Kitchen Worktops £20-£40 per m2
Average Kitchen Worktops £75-£200 per m2
Deluxe Kitchen Worktops £300-£500 per m2
Washing Machine £200-£500
Oven £300-£800
Hob £100-£400
Cooker Hood £200-£500
Dishwasher £300-£600
Fridge Freezer £200-£800
Basic Flooring £10-£30 per m2
Average Flooring £30-£60 per m2
Deluxe Flooring £50-£100 per m2
Wall Décor (Tiles/Wallpaper/Paint) £20-£50 per m2
Windows £200-£600 each
External Door £400-£900
Internal Door £50-£300
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Additional Costs

There are a number of additional costs that may come up when it comes to fitting a kitchen extension.

Below is a list of the additional costs that you may need to think about with this type of work:

Light Fittings

When you get a kitchen extension, you may need to move your light fittings so that they are centred in the room.

Although you could choose to re-install the existing lighting fixtures, now might be a good time to update them.

Kitchen extension supply cost

The average cost for installing new light fittings is around £80-£200.

The cost will depend mostly on the type of light fitting that you are having installed.

Radiator Fitting

When your kitchen is extended, it may require a larger radiator to heat the extra space in the room, or you may just want to upgrade to a more efficient radiator that will heat the space more quickly.

The average cost for removing and replacing a radiator is around £200-£300, depending on the radiator's type and size.

If you are moving the radiator to a new location, then this will require extra plumbing work and could end up costing much more.

Window Installation

Your new kitchen extension may require at least one new window, depending on the size of the extension and how much light is needed to brighten the room.

The average cost for a new window installation is around £200-£600. The cost will depend on the size of the window and the difficulty of the job.

Labour Costs and Timescales

When it comes to building a kitchen extension, there are many different parts to the job, and you will need to hire more than one contractor to get all of the work done.

Below is an overview of the contractors that you may need to hire for this type of work:

Interior Designer

If you don't have a complete idea of what you're looking for with your new kitchen extension, an interior designer could help you design your dream kitchen.

They will work with you to create an aesthetically pleasing space that is fully functional and ticks all of your boxes. An interior designer will usually charge around £25-£60 per hour on average.

Structural Engineer

It's a good idea to hire a structural engineer before you go through with an extension as they will be able to advise how practical the extension is and will be able to establish all of the alterations you can make during the extension.

They will also advise you on the materials needed to complete the job and how to ensure the new structure is safe. A structural engineer will usually charge around £40-£100 per hour on average.


Once you've got your design in place and it's ready to go, you can then start contacting builders for a quote on the building work. This way, they'll be able to give you a much more accurate price.

Always ask the contractor for examples of their previous work so that you can ensure they can complete everything you're asking for to a high standard.

You can expect to pay around £140-£250 per day on average to hire builders for this job.

Kitchen Installer

A kitchen installer can provide you with a complete, high-quality kitchen fitting. They will provide designs and manufacture units for your dream kitchen.

They will also take care of all of the installation work.

All of this will usually come as a complete price. Alternatively, you can buy your own kitchen and hire a kitchen fitter to do the installation work.

You can expect to pay around £125-£160 per day on average for a kitchen fitter.


If you are having wood cladding installed on your extension, or if you would like to have hardwood floors installed, you may need to hire a carpenter or joiner to do this part of the work.

You can expect to pay around £130-£180 per day on average for this part of the work.


Once the extension is built, you will need to plaster the ceilings and walls. Many plasterers can also render the exterior of your extension if you wish.

A plasterer will usually charge around £100-£170 per day on average.

Window Fitter

A window fitter will be able to fit any window you want in your new extension. They can also install additional things such as bi-folding doors, sliding doors, or even a skylight. A window fitter will usually charge around £110-£170 per day on average.


A roofer will be able to design the roof for your extension to your requirements. This is someone who specialises in roofing construction, and so they will be able to offer the best advice.

They will also design and build a suitable roof for your extension, which is aesthetically pleasing. Roofers will usually charge around £145-£225 per day on average.

Painter and Decorator

A painter and decorator will handle the décor of the interior and will be able to offer you the best advice on how to get your kitchen looking perfect.

Kitchen extension labour cost

They will paint and wallpaper your walls and will also gloss wooden areas such as the doorframes. A painter and decorator will usually charge around £100-£190 per day on average.

You can choose to hire a company to handle the entire extension for you. This will include all the building work, fixtures and fittings, and decorating.

Alternatively, you can take a look at the information above and shop around for various contractors for each part of the job.

Fitting a new kitchen extension will take several weeks and possibly even months to complete.

The timescales can vary greatly depending on the type of extension, the extension's size, and the additional work included, such as fitting the kitchen and any extra plumbing or electrical work needed.

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Cost Factors of Building a Kitchen Extension

Several factors can affect the cost of your kitchen extension. You can find a list of these cost affecting factors below:

Size of Extension

The size of the kitchen extension will affect the overall cost of the job. The larger the extension is, the longer the job will take, plus you will also need more materials for a larger job.

Quality of Extension

The quality of the extension will also affect the overall cost that you pay. You can pay more for top-quality materials.

If you choose to do this, the job's overall cost will increase depending on the difference in price for those materials.

It's a good idea to shop around for the best materials to suit your particular extension and your budget.

Electrical Work

There may be some electrical work involved with building your new extension. You may need new sockets or lights wiring in.

Also, depending on the age of your home and the condition of your current electrical system, you may need to upgrade your electrics altogether.

An electrician will usually charge around £120-£350 per day on average.


When your extension is complete, you'll likely need some plumbing work in your new kitchen.

Kitchen extension cost

This can include connecting the water supply to the pipework and drainage systems, installing new pipework, and connecting your appliances to the water system.

A plumber will usually charge around £120-£250 per day on average.

Location of Property

The location of your property can affect the overall cost of your kitchen extension.

Those based in London can expect to pay anywhere from 10-50% more for their kitchen extension than those based in the North or other parts of the UK.

What's Involved in Building a Kitchen Extension?

Below is a step-by-step guide on the process of building a kitchen extension. Each step represents a new week.

As you can see, it takes a lot of preparation and many weeks to complete an extension.

The guide below is a rough estimate on the timescales as each extension is different, and so the timescales will be different accordingly.

Week 1

  • Ensure access to the site is clear
  • Get all of your bricks and building materials delivered to the site
  • Ensure the area is safe and ready for building

Week 2

  • The first week of construction, the builders will come and dig up your foundations
  • Building control will need to attend to approve the new foundations
  • Reinforcements will be laid in the foundations if required
  • Pipework and drainage systems will be installed in the foundations
  • Concrete flooring will be installed and levelled off
  • Building control will return to approve the groundwork

Weeks 3 and 4

  • Bricklayers will build and install a damp-proof course
  • Lintels will be installed within the brickwork if required
  • Sand will be laid on the floor, and a damp-proof membrane will be installed
  • Insulation will be installed
  • Concrete slab flooring will be installed
  • Building control will attend and conduct another inspection

Week 5

  • Make sure all of the window frames, door frames, lintels, and wall tiles have arrived
  • The builder will create blockwork and brickwork
  • Cavity wall insulation will be installed
  • Lintels for the windows and doors will be fitted
  • Wall tiles will be installed to fix the walls together
  • The door and window frames will be installed

Week 6

  • All internal walls will be erected
  • Ensure all of the roof tiles, windows and doors have been ordered at this point
  • Double-check that your carpenter or joiner is ready for the following week

Week 7

  • Your carpenter or joiner will now build the structure for the roof
  • Rooflights and dormers will be fitted if required

Week 8

  • The roof battens will now be cut to size and fitted over the roof membrane
  • Roof slates or tiles will be installed
  • Finishing details of the roof will be installed, primed and painted/stained
  • The floor screed will be installed

Week 9

  • Any external rendering will be completed if required
  • Doors and windows will be installed
  • Drainpipes and guttering will be installed
  • Pipework, drainage, and electric work will be carried out

Week 10

  • The extension will be sealed off at this point
  • Steels and pad stones will now be installed
  • Joins will be finished to a good standard

Week 11

  • Walls will be boarded and insulation inserted
  • Plastering will be completed and should be left for around a week to completely dry

Week 12

  • The remaining electric work will be carried out, and sockets will be made live
  • Appliances will be plumbed in
  • Your choice of flooring will be installed
  • All kitchen units will be installed

Week 13

  • Any issues will be reported this week, including heating issues, electrical issues, leaks, or problems with the doors and windows
  • Any problems will be rectified

Week 14

  • Building control will return to sign off on the finished project

Can I Build a Kitchen Extension Myself?

Due to the amount of work that goes into an extension, it's not a job that can be completed as a DIY job.

There are many building regulations that need to be followed, and the job can take an extremely long time, even with a team of experienced contractors doing the work. It's important that an extension is built safely and correctly.

DIY kitchen extension

With this in mind, you should look to hire reputable contractors with all of the relevant skills and experience needed to build a kitchen extension.

Building Regulations & Planning Permission for Kitchen Extensions

Many kitchen extensions are classed as permitted developments, so there is no need to apply for planning permission. To ensure your kitchen extension is compliant, you need to make sure:

  • It is no taller than four metres
  • The extension does not extend further than six metres past the rear of an attached property or up to 8 metres for a detached home.
  • The build Is a single-storey extension at least half the size of the current building.

Before building a kitchen extension, you should contact your local council to check whether the job will fall under permitted developments.

You may need to obtain a party wall agreement and notify your neighbour before the build if you live in an attached property that shares walls.

Kitchen extension regulations

Building regulations approvals may be required at certain stages of the build. To ensure your build follows regulations, you should hire a qualified contractor who has experience with kitchen extensions.

They may notify building control on your behalf, which will involve a visit from a building control officer who will assess the build and sign off the work.

Types of Kitchen Extension

There are various types of kitchen extension that you can choose from. Below is a list of the most popular kitchen extensions:

Rear Kitchen Extension Cost

A rear extension is erected at the back of the house and often uses up space in the rear garden.

This is a great option for those who live in terraced or semi-detached houses who may not install a different type of extension due to the nature of their property. It also works great for detached houses.

Rear extensions typically range from £15,000 to £60,000.

Side Return Kitchen Extension Cost

A side return extension uses up space at the side of the house. This is a great option for those who don't want to use up their garden area.

Kitchen extension types

This type of extension is only suitable for semi-detached or detached homes with adequate space at the side for building.

Side return extensions are normally priced at £23,000 to £40,000.

Wrap-Around Extension Cost

A wrap-around extension is a combination of the side return extension and the rear extension.

This is a great option if you are looking for a large extension or don't want to take up too much room on either side of the house. This option will only work on semi-detached or detached properties.

The price you pay for each of these extension types will depend on the size of the extension, the quality of the build, and your location in the UK.

Wrap-around extensions cost approximately £40,000 to £70,000.

Benefits of Building a Kitchen Extension

There are several benefits to building a kitchen extension. Below is a list of the main benefits when it comes to this type of work:


Having a kitchen extension allows you to create more room in the kitchen so you can install aesthetically pleasing features such as a centre island. It will also open up the room and make it appear brighter and less cluttered.

You can do many things with the extra room, including adding a seating area, adding a bar, or adding extra cupboard space.

Installing a kitchen extension will give you all of the opportunities to create an inviting space for hosting, serving family meals, and maximising the room's appeal.

A kitchen extension is a very desirable feature and will add value to your home when you come to sell it.


A kitchen extension will provide you with a lot of extra space. You can use this space for several things, such as storage, which will allow your home to appear tidier and less cluttered.

You could also incorporate a seating area in the kitchen in the form of a kitchen diner extension which may free up another room in the home that can then be converted into something else.

As your family grows, it may be practical to increase your kitchen's size to accommodate for preparing extra or larger meals.

Hiring Contractors to Build a Kitchen Extension Checklist

You will need to consider a few things before hiring contractors to install an extension for you.

Below is a list of some of the main things that you should consider when looking for the right contractors for the job:

  • Does the contractor offer any guarantees with their work?
  • How much is the work to complete? – Ask for a breakdown of costs so you can ensure you are paying a good price for each element of the job.
  • Is the contractor experienced in building the type of extension that you are looking for?
  • How many years' worth of experience does the contractor have in building extensions?
  • How many contractors will carry out the job?
  • Will the contractor fix any issues that may arise?
  • Will the contractor take care of any relevant waste removal?
  • Do you need to hire any additional contractors for different parts of the work?
  • Will the contractor follow all of the relevant building regulation guidelines?


How do you plan a kitchen extension?
Below is a list of things that you can do to plan a kitchen extension:
  • Create a wish list of kitchen extension ideas
  • Set a budget
  • Find out if you need planning permission
  • Decide on the type of kitchen extension
  • Plan out the kitchen and find a designer
  • Think about your kitchen layout
  • Hire all of the relevant contractors
  • Set a timeline
How much does it cost to build a single-storey kitchen extension?
The average cost for a single-storey kitchen extension is around £25,000-£30,000.
How much value will a kitchen extension add to my home?
You can expect the average kitchen extension to add around 5-10% to the value of your home.
Do I need planning permission for a kitchen extension?
You won't normally need planning permission for a kitchen extension as long as the build follows permitted development guidelines.


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