Cost of building a Kitchen Extension

Building a kitchen extensionThe demands of a growing family, a desire to add value to your house, or simply wanting a bigger space to socialise can be some of the reasons you’re ready to press the start button on your kitchen extension project. Understanding the cost of building a kitchen extension is crucial for you to plan and make the decision.

Estimates put the cost of making your dream kitchen extension a reality in 2022 at between £30,000 and £300,000, with the average running at around £30,000, so it’s vital that you take the time at this stage to plan properly to avoid costly mistakes.

Some questions you should be considering at this stage include:

  • How big your extension is, and the volume/quality of materials required.
  • A realistic time period for the project. Allow for up to 16 weeks for a two-storey extension, for example.
  • Associated charges such as planning permission, surveys and structural engineer fees.
  • Hiring professional and skilled tradespeople to undertake the work (this is where the Guild can help).

At, our job is to help you find recommended trades including builders, carpenters and electricians to deliver the best service and keep you within budget. We have hundreds of skilled tradesmen to choose from wherever you are in the UK. Just click here to start your search.

Our guide gives you the essential information you need to know to get started and highlights some costs you may not be aware of.

How much is a kitchen extensionIs an extension right for your home?

The idea of a spacious open-plan kitchen can be seductive, but you should consider these points before taking the next steps:

  • If this is your forever home, then it’s a good option compared to buying a bigger house and stumping up for moving costs, solicitors’ fees and stamp duty. Do keep in mind that increasing the size of your home may push you into a higher council tax bracket.
  • According to, a single storey kitchen extension can add somewhere between 5 – 10% to the value of your home. So, it’s a good idea to plan your budget accordingly. Speak to estate agents in your area to get a viable estimate so your costs don’t outstrip the value added.
  • The UK government has relaxed planning rules for extensions, doubling the measurements allowed without planning permission. Now, you can add a single-storey extension of up to 3m in depth (for an attached property) and up to 4m for a detached home.

Building a kitchen extensionHow much does an average kitchen extension cost?

Fundamental costs of a kitchen extension include how many storeys you intend to build on, what size and shape you envisage, and the amount of glazing required. What quality level are you aiming for? Standard, good or excellent? And are you planning to project manage yourself? This will affect the final financial outlay per square metre. As a rule of thumb, check out these estimates for a single storey extension:

  • Basic quality: £1,350 to £1,650/m²
  • Good quality: £1,700 to £2,000/m²
  • Excellent quality: £2000 to £2,500/m² or more.

The ubiquitous side return extension, which often does not require planning permission and therefore less time, can cost around the same.

If you live in London or other high value areas in the UK, be prepared to let out the purse strings more. And of course, the sky’s the limit if you want a seriously high quality finish.

The table below will give you a guide to other key outlays:



Architect fees 

Approx 7% of construction cost

Structural engineer fees, covering foundations, roof, any large span openings and structural alterations to the existing building.





Planning permission

Approx. £206 for a single storey extension. Allow around 8 weeks for the application to be processed.

Design fees

Range between 3-7% of the total build cost.

Building regulations approvals

These vary in cost, but the certificates you require will include structure, electrics, fire safety and glazing. Click here for a full list.

Lawful Development Certificate


Party Wall Agreement 

Not always required, but between £1,000 – £2,000 per every affected neighbour if you live outside of London.

Builder, electrician and installation fees

With hundreds of skilled tradespeople at Find a Craftsman, you can take your time to find the best fit in terms of experience and budget.

New kitchen, bi-fold doors, specialist flooring, heating, glass

Many companies offer interest-free payment plans for new kitchens, with a basic set-up costing around £3,000. Aluminium bi-fold doors cost an average of £3,825. If you’ve got your heart set on a polished concrete floor, factor in around £130 per square metre. Heating the space can run at between £500 – £2,000. Basic double glazing starts at around £100 per square metre, so your visions of a light-filled space might significantly push up the overall budget.


The majority of contractors will add 20% to their services. Although bear in mind that some projects are eligible for VAT relief, so check if your build qualifies.


How much does planning permission for a kitchen extension cost?

It may be tempting to jump straight to the fun part of hiring an architect to draw up plans. But it’s essential you tick off the planning permission first. As mentioned above, a basic permit costs £206, although you must check with your local authority. Also be aware of these extra costs:

  • £200+ for projects that affect trees
  • £400+ for a mandatory ecology report in some areas
  • £350+ for a flood-risk assessment
  • £200 – £700 + (exc. VAT) for a historic building report if your home is a Grade I or Grade II-listed building.

What’s your choice of construction system?

If you’re needing a cup of tea (or something stronger) after reading the above, there are ways you can keep costs under control. Concrete blockwork is an affordable system most of our builders featured on at will be highly skilled in. Structural insulated panels are initially a pricier route to go down, but the cost will be mitigated by less labour costs on site and future savings on energy bills. A timber frame is also an option and the whole package– frame, design work, delivery and assembly – will be a one-off charge, so you won’t have any unexpected financial add-ons.

Building a kitchen extensionShould I build my own kitchen extension?

Some estimates suggest that the DIY route can save you up to 40% in comparison to hiring a main contractor who will take care of the entire project. This involves purchasing materials directly and undertaking most of the labour. But it can be a false economy if you run into serious issues, you didn’t foresee or botch up an important stage and have to go back to the drawing board. For peace of mind, it may be better to consider leaving it to the professionals. If you’re really keen to put your own stamp on the space, perhaps you could undertake the painting and decoration and save some money that way? (Although The Guild can help with that too).

Looking to compare kitchen extension costs?

Whether you have humble or grand designs for your kitchen extension, practical or show stopping, it’s important to get the basics right. After thoroughly researching your options and having a rough budget in mind, it’s time to start contacting tradespeople for a range of quotes.

The Guild of Master Craftsmen is the UK’s most established trade association, proudly representing tradespeople and artisans who have skill, integrity and expertise for over 40 years. There are hundreds of reliable, trustworthy and experienced contractors at your fingertips at Find a Craftsman for all of your tradespeople needs.