How Much a Kitchen Extension Costs

A kitchen extension opens up what has now become the ‘heart of the home,’ giving you more room to cook, entertain and live. But it also adds value to your home, making it a profitable move for when you come to sell and move on.

Side and back kitchen extensions are extremely popular in London where space is at a premium.

Many families are remortgaging to pay for the extension using existing equity in their property, while others are using savings. So, what does a kitchen extension really cost? Read on to find out the typical extension costs in the UK and London and what you need to know before proceeding.

Average Costs for a Kitchen Extension

Costs vary depending on the materials you’ll use, the size of the area you intend to build, and what type of extension you’d like. The average kitchen extension costs in the UK and London are:

UK

• Small kitchen extension (15-20 m²): £30,000 to £45,000
• Medium kitchen extension (25-30 m²): £45,000 to £70,000
• Large kitchen extension (35-50 m²): £70,000 to £120,000+

London

• Small kitchen extension (15-20 m²): £40,000 to £60,000
• Medium kitchen extension (25-30 m²): £60,000 to £100,000
• Large kitchen extension (35-50 m²): £100,000 to £150,000+

It’s mostly the additional charges for labour that put up the price for an extension in London compared to the rest of the UK.

Most tradespeople will give a cost per square metre, which is often between £ 1,500 and £ 3,000. A small extension is around 15 square metres, and a larger version can be around 48 square metres.

An average-sized kitchen extension comes in at around 24 square metres and can take up to three months to complete.

Costs by Type of Extension

A single-storey ground floor extension would usually be at the rear of a property, but not always. It could, for instance, be at the side of your property or both, i.e. a wraparound extension. Then again, it’s also possible – but much costlier – to build a double-storey extension.

Single Storey Extension

A typical single storey kitchen extension, built by a small company, and measuring around 30 metres squared will cost an average of £30,000 with a range of £20,000 to £50,000.

The same ground floor extension, built by an individual, with a high-end finish could have an average cost more in the £45,000 to £50,000 region.

Double Storey Extension

A double storey home extension project requires scaffolding, instantly adding to the cost. These are also much more complicated to design and construct. But, on the plus side, they can not only extend the size of your kitchen and living area, but also add bedrooms to your home. As a result, they can be far more expensive.

The average costs for a typical (i.e. not unusually high end) double-storey extension, measuring 45 metres squared and fitted by an reasonably-priced contractor, would be £50,000 to £70,000

Side Return Kitchen Extension

Side return extensions are particularly popular amongst owners of Victorian properties as they are a great way to introduce more light into the back of the home.

If you opted for a small company, a side return extension of about 30 square metres would cost around £50,000 to £70,000

The same extension, built by an individual, with a high-end finish would cost around £75,000.

Rear Extensions

The cost of rear extensions typically ranges from £25,000 to £40,000 for a small basic extension, £40,000 to £70,000 for a medium-sized extension and £70,000 to over £120,000 for a large extension.

Wraparound Kitchen Extension

Wraparound kitchen extensions give you the best of both worlds: a rear extension combined with a side extension. They add a lot more space to the home, making them ideal for a growing family. However, because of the extra living space, you can expect to pay quite a bit more for your new addition.

The average costs for a typical wraparound extension, built by an averagely-priced company would be £70,000 to £100,000.

Kitchen Conservatory

A kitchen conservatory costs less than an extension since it’s quicker and easier to construct – they‘re actually often built offsite and simply added to your home. Similarly to an extension, they can help to create a larger kitchen and dining space. The difference between conservatories and extensions is that the former tends to let in more light, since it comprises mainly of windows, with a composite roof.

Costs Breakdown

There are a number of costs involved in the building of a kitchen extension. As well as the labour costs, there are the materials to think of and the installation of electricity, gas and water.

And that’s just for starters. You’ll also have to pay for your architect’s design of the home extension (this often works out at around 10 per cent of the cost of the building) and any surveys or permits necessary. Trade professionals will vary in their charges for building work, but the following is a rough estimate of costs:

Interior Designer Costs

Hiring an interior designer for your kitchen extension can significantly enhance the final result. They’ll help you maximise space, select materials, choose colour schemes and ensure the new extension seamlessly integrates with your existing home, potentially saving you money by avoiding design mistakes that you’ll want to fix in the future. However, the upfront cost will impact your budget quite significantly, with project fees typically ranging from £1,500 to £5,000 depending on the asks and complexity,

Structural Engineer Costs

A structural engineer is crucial for ensuring your kitchen extension is safe, stable and compliant with building regulations. Their services usually cost between £500 and £2,000, depending on the project’s complexity and size. They’ll provide detailed plans, calculate load-bearing requirements of internal walls, specify necessary structural modifications and prepare technical drawings to submit to your local planning authority and to help your builder.

Carpenter or Joiner Costs

Carpenters and joiners are key to creating bespoke elements in your kitchen extension, with rates typically ranging from £130 to £180 per day. Their work might include custom cabinetry, shelving, fitted furniture or intricate woodwork that transforms the space. Costs vary based on the complexity of the design, materials used and the level of craftsmanship required.

Plasterer Costs

Plastering is essential for creating smooth, professional-looking walls and ceilings in your kitchen extension. Professional plasterers typically charge between £100 and £170 per day, with a small room taking approximately 1-2 days to complete. The costs depend on the wall area, the condition of existing surfaces and the desired finish.

Window Fitter Costs

Window, skylight or bi-folding door installation is a key component of your kitchen extension, with professional fitters charging between £110 to £170 per day. The total cost depends on the type, size and number of elements being installed. Modern, energy-efficient windows, including installation, can range from £500 to £1,500 each. A skilled glazier will ensure proper sealing, insulation, and alignment, preventing future issues like drafts or water ingress.

Roofer Costs

Roofing for a kitchen extension typically costs between £1,500 and £5,000, depending on the size and complexity of the roof. Factors influencing price include materials (such as tiles, felt or modern alternatives like GRP), roof pitch. A professional roofer will ensure proper waterproofing, insulation, and structural integrity, protecting your new extension from weather-related damage.

Painter and Decorator Costs

Painters and decorators typically charge £150 to £250 per day, with rates varying based on location and experience. They’ll prepare surfaces, apply primers, paint walls and ceilings and potentially add decorative touches. While it’s possible to do this part yourself, a skilled painter can transform the space, protecting surfaces and creating a polished, professional look.

Material Costs

The materials needed for a kitchen extension span structural, insulation, roofing, glazing, plumbing, electric and interior requirements. The cost really depends on the scale and finish: you can get basic materials from around £19,000, but if you’re looking for a high-end finish then you could pay more than twice this, at around £48,000.

Electrical Costs

Installing new lights and sockets is a key part of your kitchen extension. Expect to pay anything from around £120 to £300 a day for an electrician.

Plumbing Costs

Once your new kitchen is built you’ll need the appliances plumbed in and a working water supply set up. This means connecting the water to the pipework and drainage systems.

For a plumber, you’ll pay from £120 to £250 per day.

New Kitchen Costs

The cost of a new kitchen depends on the quality of the kitchen units, worktops and appliances that you’re looking for. Basic cabinets cost from £3,500, for instance, while luxury cabinets often come in at above £5,000. You’ll then have to pay for a kitchen fitter. He or she will charge anything from £125 to £160 per day.

Fixtures and Fittings Costs

You’ll no doubt require new light fittings for your new kitchen extension. For these, you can expect to pay from £100 to £300, depending on just how much you want to invest in this part of your décor.

Scaffolding Costs

The construction of your home extension may involve scaffolding, especially when it comes to installing the roofing and a Velux window or two. This normally works out at around £625 a week for a single scaffold of up to 10m high.

Skip Hire Costs

You’ll usually need to hire skips and get a permit for them if they’re going to be on the road. A builder’s six to eight-yard skip comes in at an average cost of £220 to £410 a week.

Rental Costs

Not only is it hard to function at home without a kitchen, but having an extension built can result in a lot of dirt and mess which you don’t want trailed around the rest of the house. For these reasons many homeowners opt to rent a property for a few months while their property is being remodelled, which can certainly add to the overall cost of the extension.

Factors that Affect Costs

Having a kitchen extension built isn’t a ‘one size fits all scenario’ with a typical fixed cost. There are plenty of different issues which can affect the cost of your renovation – even if you’ve chosen the same type of extension as your neighbour opposite.

The type of professionals you require ie soil samplers, tilers, and carpet fitters, will matter as well as whether they are self-employed or work with a company (the size of that company will also matter since larger companies will tend to charge more). In addition, extensions to property in London will always cost more, due to the higher cost of labour there.

Size and Type of Extension

The size of the extension will obviously affect the price, as will the difficulty (or simplicity) of the design

A wraparound extension will be far larger and more complex to build than a single storey rear extension so will obviously cost more. The same applies to a double storey extension. An extension can be any size and the larger it is, the more materials you’ll use and the longer tradesmen will remain onsite.

Structural Changes

If you have a neighbour whose property adjoins your own then you’ll need to get a party wall agreement. This can come to about £1,000 and you’ll require the assistance of a structural engineer.

Surveys you may be asked to undertake before starting the build, in order to comply with Building Regulations, include those for the potential of flooding and how the build will affect the natural environment and wildlife in the area. These typically cost around £700.

Quality of Kitchen Components

The type of materials you choose will certainly have a bearing. A worktop with a composite finish will cost a lot less than one made from Italian marble, for instance.

When it comes to fitting out your kitchen extension, there’s a rough estimate of what the materials, such as cabinetry, worktops and appliances will cost.

The percentage is based on the overall value of the property, with five per cent spent on the interior of the new kitchen extension. This breaks down further into:

• 30 per cent of your budget on cabinetry
• 15 per cent on appliances
• 10 per cent on worktops
• 5 per cent on flooring

Planning Permission Fees

As well as complying with Building Regulations, your extension may also require planning approval from the local council (which costs around £200 per application).

It can be possible to use permitted development rights to add on a ‘larger rear extension’, but this must be given the go ahead by the local authority. An application for this is around £100.

The Process

A kitchen extension involves multiple stages, typically spanning six months to year (maybe longer) from initial planning to completion. The process begins with consultations with an architect or designer, followed by obtaining necessary planning permissions and building regulations approval. Next, you’ll select contractors, with a detailed tender process helping you choose the right professionals. The actual construction involves groundwork, structural modifications, building the extension, installing utilities and finishing with interior work. Careful project management and clear communication are both crucial to ensuring a smooth, successful kitchen extension that meets your vision and budget.

Reasons to Get a Kitchen Extension

If you need extra space for a growing family, a kitchen extension is far more cost-effective than moving house and also less hassle.

Another plus point of an extension is that you’ll usually recoup much of the cost when you eventually come to sell the house, as typically extensions add value.

DIY Vs Hiring a Professional

Yes, you’ll pay a lot more to have your kitchen extension professionally built, than if you do it yourself. But, you’ll also have the peace of mind that it’s been done properly, and in a reasonable timescale.

You’ll also get a legal guarantee with the extension if it’s been carried out by a team of professionals.

Finding Someone for Your Kitchen Extension Project with The Page

At The Page, we can match you with a curated list of tradesmen specifically suited to carry out the work you require:

• Find someone to build you an extension
• Find someone to create you a new kitchen

You can rest assured that all tradesmen listed on The Page have been personally met, verified and their work assessed. Where applicable they are also members of a professional body for their particular trade.