Knowing how much a kitchen extension costs before you embark on your home improvement is vital. It will allow you to draw up a budget that includes all the elements this project entails so you can create the room you’ve been dreaming about.
Increasing the size of your kitchen is a popular way of extending a house, allowing you to say goodbye to a cramped cooking space that doesn’t connect with the garden and instead enjoy a spacious, light-filled modern room that’s a pleasure to cook in, has room for dining, and is a great place to spend time with friends and family.
There are many different factors that influence how much a kitchen extension costs from the building work to professional fees, any necessary permissions, and more, and our guide will provide the information you need on all of them. We’ll also let you know how you can make your money go further.
You can check out our extension cost calculator below, too, which will give you an estimate of what your kitchen extension will cost you wherever you live in the UK.
How much does a kitchen extension cost?
How much it costs to expand a kitchen all depends on how much work you plan to do. As well as build costs and professional fees, there will likely be the cost of applying for planning permission and getting building regulations approval to include also. Finally, you need to budget for the kitchen itself, including flooring and decoration.
When you are setting a budget for your kitchen extension, there will be a certain amount of flex in each stage, so we have broken the project down into cost areas.
Our expert tips provide all the information you need to achieve your ideal kitchen extension, while ensuring you set a realistic budget (and then stick to it), and you can find plenty of inspiration among our kitchen extension ideas under £200k and kitchen extension ideas for period homes.
How much are kitchen extension build costs?
Use this kitchen extension cost guide to understand what you might expect to pay for building work.
Fitting bespoke windows and doors: ‘There are many variations on bespoke windows and doors, however, prices for bespoke windows and doors can be up to £1000s per unit,’ says Emma.
Redesigning work, such as reworking an interior layout is likely to cost £500 to £900 per m².
Extra foundation costs will be incurred by difficult ground conditions, such as clay, peat, nearby trees or slopes. Ask a structural engineer (find one at istructe.org) and your local authority building control for an idea of likely foundation type.
Top tip: ‘Small extensions under 15 to 20m² achieve no economies of scale, so costs are higher per square metre,’ says experienced renovator Michael Holmes.
How much do kitchen extension professional fees cost?
Design fees for a kitchen extension will range from three to seven per cent of the overall build cost.
Planning drawings will cost around £2,700.
A measured survey of the existing house will cost from £800 to £2,000, depending on the size of the property.
The fee for construction drawings that are sufficient to build from (and for building regulations approval) will typically cost the same as planning drawings at around £2,700.
Structural engineer’s fees will range from £800 and are necessary to design the foundations, roof, any large span openings and structural alterations to the existing house.
How to control kitchen extension building costs
You can use our extension cost calculator to estimate how much adding a kitchen will cost you in your area when drawing up your budget, but bear in mind there are ways to cut the cost of an extension. You will also want to investigate ways to cut the cost of the kitchen itself.
‘Gather multiple quotes for the work before hiring any tradespeople, so you can be sure you’re getting the best deal,’ recommends Gregory Smith, property and construction expert at PriceYourJob. ‘Keep the extension within permitted development to avoid added planning costs (see below) and keep the design simple to minimise the need for complex structural work. This will bring down the cost of materials and labour.
‘To lower the cost of fixtures and fittings, choose basic kitchen carcasses and finish with quality doors and worktops. Most kitchens come in flatpack form, so you could fit these yourself to lower costs further.’
Fitting a kitchen is in the grasps of those competent at DIY and could save you £1,000 to £5,000.
Michael Holmes advises, ‘Agreeing an all-in rate, plus reasonable expenses and disbursements, gives greater control of costs for planning and construction design.
'If the architectural designer is retained to help put the project out to tender and appoint the builder under a formal contract, as well as to provide contract administration services, the fee will typically be a further three to seven per cent of the total contract value.'
'For a more ad hoc site attendance, service troubleshooting or adding design detail during the build, it is reasonable to agree a daily or hourly rate.’
Using standard building materials will help to keep the total lower as builders will be able to negotiate better deals. Doors and windows in regular sizes rather than bespoke will reduce costs. But that doesn’t mean you can’t be creative when you design an open plan kitchen diner, for example by exposing roof trusses for an impressive ceiling, using an interesting bond pattern for bricks or, as here, setting bricks on end.
This extension (above) to an Edwardian terraced property features distinctive brickwork and includes a bespoke kitchen, from £40,000, Onestà.
As for the cost of the kitchen itself? ‘A modest budget should never be an obstacle in achieving the kitchen of your dreams,’ says Ruth Lavender, design expert at Benchmarx Kitchens. ‘Advancements in the manufacturing of today’s kitchens have created endless opportunities to recreate high-end looks at cost-effective prices. Simply choosing clever combinations of cabinetry, worktops, lighting and appliances make it possible to create an expensive feel without overstepping on costs.’
Setting aside contingency funds for a kitchen extension
As you should when assessing any house renovation costs, build a contingency fund into your budget.
Let’s assume you have set a budget of around £22,200 for an extension measuring 4m x 3m at £1,850 per square metre, plus a new kitchen cost of £10,000. Always add in at least another £3,220 as a 10 per cent contingency should anything unforeseen occur.
Do you need planning permission for a kitchen extension?
If you take this route, it’s still worth getting a certificate of lawful development, which costs £103 in England. This is useful when you come to sell as you will be able to show that your kitchen extension did not require planning permission.
How much does planning permission for a kitchen extension cost?
If your kitchen extension needs planning permission, the fee for a residential single storey extension in England is £206.
If your extension requires planning permission, you may need the following additional reports:
- If your project affects trees, a tree report, at a cost of £200 upwards;
- If your home is within a flood zone, a flood risk assessment: £350 upwards;
- Many local authorities require an ecology report: from £400 upwards;
- In areas of archaeological interest, an archaeological report based on a watching brief during excavation: this can cost several thousand pounds;
- If your home is listed, a historic building report is likely to be required.
What are building control costs for kitchen extensions?
Fees for building regulations approval will depend on the size of extension. ‘Single storey would cost around £350; £550 for double storey both with a private building control company,’ says Emma.
‘You should always ask your builder which building control company they like to work with as having a strong relationship with your inspector can help avoid delays on site and added costs,’ she advises.
How much does a party wall agreement for a kitchen extension cost?
A chartered surveyor can arrange party wall agreements for your kitchen extension. ‘Costs depend on how complicated it is and if a party wall surveyor is required could be up to £1,000 plus VAT,’ says Emma.
There are ways to save. ‘If your neighbour formally consents to the works, you can avoid having a party wall settlement and save on the fees,’ says Michael; the government’s planning portal has details.
How much are kitchen extension design costs?
Kitchen extension design can be anywhere from £17 per m² to £144 per m², bearing in mind that costs can be much higher for a bespoke option. The costs of the design work may be included in what you spend on the kitchen itself, or reflected in your total architect fees.
Kitchen extension bi-fold and sliding door costs
Whether yours is a period home or a contemporary one, you may well want to include bi-fold or sliding doors in your kitchen extension design. So what should you expect to pay? Expect to pay an average of £3,825 for aluminium bifold doors and £3,000 for aluminium sliding doors, according to Checkatrade.
Kitchen extension lighting scheme costs
A kitchen lighting scheme from a specialist designer can be well worthwhile. ‘Operate ambient, accent and task lighting on different circuits, for control of zones and the freedom to alter the mood,’ says Luke Thomas, associate at John Cullen, which charges from £102 per hour’s consultation.
Kitchen extension concrete flooring costs
Concrete flooring is on trend and hardwearing kitchen flooring. ‘It can be laid both internally and externally, giving spaces impact,’ says Jonathan Reid, director of GreyMatter Concrete. Expect to pay from £120 to £144 per m² for a 50m² 10cm thick floor.
Kitchen extension tile costs
Kitchen tiles are an excellent way to make a statement. ‘There are so many options, from rustic terracotta to hand-poured encaustic tiles,’ says Harriet Roberts, co-founder of Bert & May, which offers reclaimed tiles, with prices starting from around £100 per m². However, if you shop at DIY sheds or larger chains, such as Topps Tiles, you can find wall and floor tiles for as little as £10 per m².
Kitchen extension heating works costs
You’ll need to consider heating a kitchen in a new extension, and underfloor heating is an option. ‘If you have a relatively new and energy-efficient boiler, check whether it is powerful enough to handle the additional heating demand,’ advises Michael Holmes. ‘If your boiler is more than 10 years old, consider replacing it, as a more energy-efficient design will help offset the cost.’
Kitchen extension decorating costs
The average cost to paint a room is £400, according to Checkatrade, while you can expect to pay around £650 to tile a kitchen floor, experts there say.
‘Decorating is one of the easier DIY tasks for those looking to reduce costs of an extension,’ says Michael. ‘Skilled decorators tend to spend more time prepping than painting and this makes all the difference to the finish, so if you plan to decorate, don’t cut corners on sanding, filling, priming and undercoating.’
‘Tiling is a skilled job and, given the high cost of tiles, is not one to complete on a DIY basis unless you have the skill, time and a good quality tile cutter.’ If you think you're up to the job, our guide to tiling a wall is a great starting point.
‘Second-fix carpentry is another good area for the skilled DIYer,’ adds Michael. ‘Laying wooden flooring, hanging doors, installing skirting and architrave and fitting the kitchen itself are achievable tasks. Fitting worktops requires more skill and the correct tools for cutting out sinks.’
How much will a kitchen extension add to the value of your home?
When working out kitchen extension costs, it's vital to consider how much the project might add to the value of your home so you can ensure what you spend doesn't outstrip this figure.
‘Kitchen extensions are definitely seen as a great way to add value to your home as the kitchen is what really sells a home,’ says Emma. ‘Nowadays, people expect a large family/entertaining space centred around the kitchen.’
Gregory agrees. ‘If your existing kitchen is small and impractical for modern living, then an extension is going to add value. Especially so in family-sized houses, as it will be at the top of potential buyers’ priorities for a new home. They’ll be expecting a kitchen design that’s big enough to house all the mod cons, along with plenty of space for dining.’
It's really worthwhile speaking to local estate agents for a more accurate estimate when planning your kitchen ideas, but as a guideline, a single storey kitchen extension can add somewhere between 5 and 10 per cent to the value of your home; while double storey extensions with an extra bedroom may add up to 20 per cent. This is very dependent on the local market, the quality of the extension you add and many other factors – which is why it's worth speaking to a trusted local agent first.