Kitchen extension cost - what to budget for a new and large room

Thinking of upgrading your kitchen? Here's how much it will cost, according to the experts

Kitchen island and pink cabinets with white countertop in front of bay windows
(Image credit: GOAStudio + Kitchen Co-ordination)

If you and the family have outgrown your current kitchen and are currently dreaming wistfully of extending, there's probably one thing making you hesitate: the kitchen extension cost.

Kitchens have long since surpassed serving a single function of cooking and eating; they can now also be a place to do school or office work, household chores like the laundry, as well as a socialising space for guests and residents alike. Enter kitchen extension ideas to save the day, and expand the kitchen so that it can serve the growing needs of the house.

But there's no denying that extending a kitchen is expensive, and it's important you take the time to understand by exactly how much. There's a lot of factors that will affect the kitchen extension cost, which is why we've asked the experts to tell us all so that you can plan and budget for the kitchen of your dreams.

Our guide will take you through everything you need to know, from the factors that influence kitchen extension cost, to the current prices you can expect to be facing. Keep reading to have all your questions answered and to start bringing your new kitchen into reality.

Pink kitchen cabinets with matching island

(Image credit: Herringbone Kitchens)

Kitchen extension costs - everything you need to know

George Omalianakis chartered architect
George Omalianakis

George Omalianakis is an expert residential and award winning architect, member of the Royal Institute of British Architects (RIBA), registered with the Architects Registration Board (ARB), and member of the Green Register of Construction Professionals.

An RIBA residential architect is the professional to guide you through your kitchen extension project, develop your design ideas, obtain local authority and other approvals on your behalf, and manage the whole process from initial sketches to liaising with the builder and all other professionals.

'Firstly, it should be noted that estimating exactly how much a kitchen extension will be is difficult, as it completely depends on the size of the extension and the age of the property', says William Durrant, Owner, Herringbone Kitchens. 'And also whether you're going for a bespoke kitchen or off the shelf.'

Being as detailed as possible with your architect or builder is important, as they'll be able to give you a more accurate figure of how much the extension is going to cost. The more you plan your extension and specify exactly what you want, the easier it will be for the workers to give you a price. 

The Hillarys renovate or relocate tool predicts that a kitchen extension could currently cost up to £30,000, and take 11 months to complete. This is just an average figure, and should by no means be taken as the expected price of your extension. We recommend getting several quotes before you commit to one. Try sites like MyJobQuote and PriceYourJob. There's also a kitchen extension cost calculator on MyBuilder.

U-shaped kitchen layout with glass patio doors

(Image credit: GOAStudio)

What factors affect kitchen extension cost?

There are several factors which directly influence your kitchen extension cost: 

  • Size of the extension
  • Location
  • Structural changes, bespoke features and finishes
  • Planning permission fees

Size of the extension

White kitchen cooking island in front of large dining area

(Image credit: GOAStudio)

The larger the extension, the more it will cost. That much is obvious. 

Sometimes builders will give a quick estimation of how much the extension is going to cost per sq m, for example £2000/sqm for the floor area added. This would mean that for a basic extension of 12sqm the cost will be £24K, though this only covers the main building work, and excludes glazing products, kitchen fittings, and any particularly expensive finishes that are priced separately. 

But, the economies of scale also apply. A builder could say that the first 12sqm will be £2000 each, but after that the price per sq m will drop to £1500. The larger the extension is the less it tends to cost per sqm of floor area.

You want to land on an extension size that is just large enough to meet your internal needs. Going beyond this would be a waste of money. 'You will discover the right size by playing around with a few plans and layouts to see how best you can organise the internal space', says George Omalianakis, Residential Architect ARB / RIBA, GOAStudio. 'The extension should do the bare minimum to allow sufficient circulation and meet your needs.'


Pink kitchen cabinets with white countertop in front of bay windows

(Image credit: Herringbone Kitchen)

Kitchen extension cost will vary across the country; the same project will produce different quotes in different places. 

'Costs tend to be higher in London by a factor that varies by around 20% compared to the rest of the country', explains George. 'This is because labour wages tend to be higher and various other costs are higher too. Also, in London a kitchen extension project might cost more due to site access or other site related difficulties that need to be factored in by the builder.'

So if you're a London resident you can expect to see a higher kitchen extension cost. Any project with difficult site access will also be more expensive.

Structural changes, bespoke features and finishes

Brick wall kitchen with wooden and grey counters and island units

(Image credit: GOAStudio)

'In construction terms you will want to avoid complex structural alterations (requirement for beams = costs)', says George. 'Your architect and structural engineer will help you assess this and find the most straightforward way to meet your requirements.' 

If your extension simply involves knocking down a wall and building a new one, this isn't going to produce sky-high prices. But if your extension requires new beams, an island unit, bespoke windows and doors, and a new sink fitting, you're going to see the cost rocket upwards.

Glazing products, like skylights, rooflights or glazed boxed windows will likely add an extra few thousand on to the final price, as will new fittings and appliances. Does your extension involve a new oven, fridge freezer, dishwasher and sink? If so, you'll have to start asking around kitchen designers and suppliers for quotes that meet your budget.

There's also the quality of materials to think about. You could go for gold-plated taps, a copper splashback, and corian, concrete or granite worktops if you wish, but be prepared to pay a lot more. 

'In terms of kitchen floor finishes, you can go from a budget vinyl or wood-effect laminate option (from around £15/sqm supply), to ceramic tiles (from around £20/sqm), to engineered timber flooring (from around £40-80/sqm) to polished concrete finish as a feature flooring (from around £100/sqm)', summarises George.

Permission planning fees

open plan kitchen backing on to garden through glass patio doors

(Image credit: GOAStudio)

'If you need planning approval for your kitchen extension you will need to pay a fee of £234.00 to your local planning department for them to assess your application and hopefully approve it', says George. 'If your extension can be considered under Permitted Development then the application fee for the submission is currently £103.00 in England, though these fees tend to go up and always check with your local planning authority or ask your architect to advise on the current fees.'

It's likely that your project will also need a Building Regulations approval in addition to the planning approval. For a typical extension you can budget anything between £600-£1,200 for this. Before you make the submission you can ask the Building Regulations Inspector to review your plans and prepare a quote for this fee to know in advance how much it will cost.

A few other fees may or may not be relevant to your extension project. If you build near the boundary with your neighbours, a fee of a few thousand pounds will need to be paid to a Party Wall Surveyor, who will carry out a condition survey, liaise with both Parties, and put an agreement together. If your extension is near a public drain at all, it will need to be approved by the local water authority, which will be another few hundred pounds (currently the discounted online submission fee for Thames Water is £299.00, as an example).

Lastly, if your property is under a leasehold ownership then you will need your Freeholder to agree to any alterations you do to your property. This will bump the overall kitchen extension cost up further, as you may need to account for solicitor fees.

How much is a kitchen extension 2022 UK?

View of white kitchen with wooden furniture from patio

(Image credit: GOAStudio)

'Realistically, you’re looking at paying an average of £30,000 for a kitchen extension in 2022', says Thomas Goodman, Property Expert, MyJobQuote. 'But costs do vary. A small kitchen extension without any fancy features may only cost £16,000. But if you go for a large extension with a bespoke design and high-end fittings, you’re likely to pay nearer £100,000.'

It's helpful to think of kitchen extension cost in terms of cost per sq m, as you'll be able to track the rise in price along with the increase in size. 'You can expect to pay around £1400 - £2000 per sq m for a kitchen extension in 2022', says Natalie Mitchell, Property Expert, 'In addition to the extension, you may also have to buy the kitchen suite (appliances). You can expect to pay around £200 - £1000 per sq m for the kitchen suite.'

Natalie gives the following price brackets as a rough guide for the current price of kitchen extensions:

  • A small kitchen extension of around 6 sq m would cost around £9600 - £18,000
  • A medium kitchen extension at around 9 sq m would cost around £14,400 - £27,000
  • A large kitchen extension at round 18 sq m would cost around £28,800 - £54,000
  • A small kitchen suite (6 sq m) would cost around £1200 - £6000
  • A medium kitchen suite (9 sq m) would cost around £1800 - £9000 
  • A large kitchen suite (18 sq m) would cost around £3600 - £18,000

These price brackets are fairly broad, but they should point you in the right direction in terms of an estimated price. It's always better to think of the cost as landing on the higher end of the scale, to cover any unforeseen expenses.

Is a kitchen extension worth it?

Obviously you're going to be wondering whether a kitchen extension is worth investing such a large amount of money. Aside from making serious improvements for the household to experience right now, a kitchen extension will add value to your home and give you a higher return on investment, should you decide to sell up in the future.

'Any extension that is not awfully oversized and disproportionate to the size of your home is likely to add more value than the cost of building it', says architect George. 'When it comes to assessing the financial value of adding a kitchen extension, the local estate agents are your best friends.'

'Ask them what type of kitchen extensions are the most desirable in the area, what kitchen-adjacent spaces are a must to potential buyers. You'll be able to get a better sense of where to draw the line when it comes to the cost of the fittings, units and appliances.'

What is the cheapest type of extension?

Wooden floor and dining table in open plan kitchen

(Image credit: GOAStudio)

'With the rising cost of materials and labour, a kitchen extension is unlikely to be cheap', says Thomas, MyJobQuote. 'But you can still minimise costs by sticking to a simple design and by using materials that are easy to source.'

A single storey extension with a simple design is going to be the cheapest to build, especially if it's a small rear or side return extension. If you have a garage, it might be worth considering converting this into extra kitchen space, as most of the structural work will already be in tact. 

'Consider space-saving bench seating dining arrangements and alternatives to island units (such as L-shaped or U-shaped kitchen layouts) that are still able to accommodate breakfast bar areas in less space', suggests George. 'And when it comes to glazing, you want to avoid glass-to-glass assemblies. You can create a lot with standard sized skylight, door and window products.' Opting for Velux roof lights and uPVC patio doors rather than bespoke glazing will keep the kitchen extension cost down.

If the kitchen itself is more of an issue than the size, it might be worth looking into how to buy a second-hand kitchen, as this will give your culinary space a complete revamp for a fraction of the price of an extension. 

Katie Sims

Katie Sims has been writing for Ideal Homes since spring 2022. She qualified from her Master’s in Media and Journalism in 2021 and has been writing freelance since. She has worked on Ideal Home’s ecommerce team where she researched the best home products on the market, and on the news team, researching the latest trends for feature pieces.