How Much Does A Kitchen Extension Cost In 2021

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Kitchen extensions are one of the most popular renovation projects, and for good reason. Not only can a well planned kitchen extension change your home and the way you live, but it can also add value when you come to sell it.

There are so many items that need to be budgeted for a kitchen extension; not only the construction and the kitchen itself, but other costs such as professional fees, application costs and windows & doors, amongst many others.

We look at all of the costs that you should budget for when calculating your kitchen extension cost, to make sure you have tight control over your project...plus some inspiring kitchen extensions too!

If you are thinking about a kitchen extension in the near future and need some help finding an architect or designer, we can match you with the most suitable ones for your project.

Find an architect

Kitchen extension by Ask My Architect

So how much does a kitchen extension cost?

If you want a quick high level kitchen extension cost, our extension cost calculator will be able to give you an estimate. Our cost calculator should only be used as a guide and you can refine your costs as you go through your project with help from your architect and builder.

Once you have an idea of the high level kitchen extension cost, it's good to draw up a detailed budget to make sure that your costs don't escalate. 

We will cover off the main costs that you will need to consider for your budget. If you want a template to use, then our budget tool is really helpful and you can update it for your project.  

Contemporary kitchen extension by Cryer & Coe Architects

Labour and Build Costs

Labour and build costs are the chunkiest element of a kitchen extension cost - you will often see costs quoted per square metre.

The labour and build costs per square metre will vary greatly depending on many factors, including your location in the UK and the type of finish. 

For example, a simple brick kitchen extension will be easier and cheaper for a builder to carry out. You will also have a larger number of builders to choose from if the project is straightforward. 

If you are using high end materials and your design is complicated, it will take your builder far longer which will add to the labour and build costs. You may also find that some builders won't want to work on a kitchen extension that is niche in design, so you will have fewer builders interested in your project which could add to the cost.

Brick extension with an apex roof by The Practical Planning Company

Broadly speaking, labour and build costs range broadly from £1,200 + VAT to around £2,500 + VAT. The upper end would be in the London area with a high-end finish, with the cost lower outside of London and the South-East of England. 

Often overlooked when trying to calculate an initial kitchen extension cost is the VAT, where you should add 20% to the build costs. This is so important and you should factor these costs from the outset.

With an increase in construction costs in the current climate, it's sensible to be prudent when budgeting for the labour and build costs. A contingency of 15%-20% is always recommended to help with any unforeseen price rises.

Remember when your builder quotes for your kitchen extension cost, they will not quote for a price per square metre but will break it down based on a detailed brief. The greater the detail that you provide the builder, the more accurate the price will be. This will also make it easier when comparing quotes with several builders, as well as stopping the costs escalating when they start the build.

Kitchen extension with a large sky lantern and bi fold doors by Mulhern Iremonger Design Studios

Professional Fees and Application Costs

Before you start any build work, a significant part of the overall kitchen extension cost is the professional fees and application costs. These can vary depending on the scale of your project and who you involve in helping you to plan your renovation.

Architects fees can vary depending on what you need them to help with and what type of architectural designer you work with. 

Architects or designers fees can start from around £800 for a planning application, through to several thousands for designs and planning application costs, with a RIBA Architect being more expensive than an architectural designer. 

If you have a large project, you may wish to use an architect to tender with builders and project manage your build. This would be an additional fee, and this type of work is often calculated as a percentage of your overall labour and build cost.

The cost of planning permission for your kitchen extension is £206 (in England & Wales), the cost is roughly the same across the UK. You may not need to apply for planning permission, however if you don't it's sensible to apply for a lawful development certificate which costs around £100 across the UK.

A building control application will require a structural engineer to carry out the calculations for the application. These will also be hugely important for the builder. Expect to pay from £500 for the structural engineers fees however this may increase for larger, more complicated projects. There will also be an additional cost from your architect for the structural drawings, which is often quoted in the upfront planning and application fee from an architect.

All kitchen extensions will require a building control application and you should expect to pay in the region of £800 - £1,000 for the application and inspector fees. The costs vary depending on your local authority and the scale of your project.

It's also worth including a budget for surveyors fees which could include work on the Party Wall, drains, bat or tree survey. 

Rear extension creates a wonderful large kitchen by Lost and Found Architects

Kitchen Products

The exciting part of any kitchen extension is choosing the new kitchen. Make sure you spend lots of time researching what you like, looking for inspiration on social media and pinning with wild abandonment!

The cost of the kitchen can start at around £5,000 and can go anywhere in excess of £60,000 for a handmade bespoke kitchen.

If you are looking for something at the budget end, think about upcycling a second hand kitchen - it's good for the environment and you could get really great value for money. 

Popular kitchen manufacturers that don't cost a fortune and are still quality projects include Howdens, IKEA and DIY kitchens. These are standard in style but can really look wonderful, especially if you style them with the right worktops and accessories. 

Another popular option is choosing cabinets and worktops to fit an IKEA or Howdens kitchen. Not only will you save on the cost but you will still get an individual and bespoke look. You should pay around £10k for this type of kitchen.

Mid range kitchens are around £20,000 from a kitchen designer or showroom. This cost will vary depending on the size of your kitchen and the finish too.

For a handmade, bespoke kitchen then you will pay far more due to the materials used and the time involved for the carpenter to make it, where you pay anything in excess of £40,000. This option is worthwhile if you have a large budget and plan on staying in your home for the foreseeable future.

Large side return kitchen extension by Amos Goldreich Architecture

Windows and Doors

For many, sliding, bifold or patio doors in the kitchen extension will give it the wow factor. The costs of doors vary depending on the material used, the size and the type of finish. For example, a minimal framed sliding door will cost far more than a standard frame. Similarly Crittall steel will be a huge investment in your kitchen extension and add a large proportion to the cost. 

Expect to pay around £1,200 - £2,000 / square metre for bifold doors, with sliding doors costing around 50% extra. Steel framed doors (often referred to as Crittall doors) will cost around £3,000 / square metre, so if this is out of your budget then consider aluminium replicas.

Incorporating skylights or a lantern will bring in even more light in your kitchen extension. The higher spec you go here will add to the kitchen extension cost. If you are looking to save, off the shelf velux windows can cost from around £300 - £500. Expect to pay from £1,000 per square metre for a custom made skylight, with the costs increasing with added features. 

In terms of standard windows, you may be replacing these as part of your kitchen extension. The cost of new windows vary depending on the material used, so expect to pay from £150 / metre for a standard PVCu and around £1,000 / metre for a wooden sash window.

Large modern extension by Emmett Russell Architects

Other Products

All of the other extras add on quite a bit and start to creep up, so it's important to have tight control of these costs when planning a kitchen extension.

In terms of kitchen flooring, there are so many amazing options to consider. A luxury vinyl will cost around £20 / square metre. Expect to pay around £30 - £40 / square metre for a porcelain tile and around £50 - £60 / square metre for a good quality engineered wooden floor. 

Items such as the fridge, oven and extractor fan should also be budgeted early on. If you are looking to get an instant hot water tap then this will again cost far more than a standard tap - you will pay from £400 to over £1,000 for an instant hot water tap.

Other kitchen extension costs to consider include handles, internal doors, paint and skirting. It's important to get a detailed view of these costs early on to stop the costs escalating.

Single storey kitchen extension by Hough Architecture

Heating 

A kitchen extension is a great time to install underfloor heating, as it's far best to fit it during the upheaval rather than retrospectively. The upfront costs can be significant however you should expect a reduction in energy bills as well as taking up less room on the walls with the radiators, making it easier to plan furniture layouts. Expect to pay around £80 - £100 / square metre for a specialist installing wet underfloor heating.

If you don't opt for underfloor heating then you will need to allow a budget for radiators. Also consider whether you are replacing the boiler as part of the kitchen extension. It's often a good time to relocate your boiler if it's taking up space in a kitchen cupboard. A straightforward boiler swap will cost around £2,000, with the cost rising if you are moving the boiler or changing the pipes to cope with more pressure.

Kitchen extension by Cryer & Coe Architects

Don't Forget the Contingency

With rising construction costs, it's more important than ever that you include a contingency within your budget for your new kitchen extension. 

A sensible contingency would be an additional 15-20% of the labour and build cost, which could help mitigate any additional construction costs.

Remember to have trade-offs so that if your kitchen extension cost is rising beyond your contingency then you have ways to mitigate it; this might be the type of flooring or kitchen products.

There are other ways to save on your kitchen extension cost, from the design to the materials used, if the cost is coming in more than you anticipated.

Large kitchen extension by Alexander James Associates

What Else Should I Consider For My Kitchen Extension Cost

If your kitchen extension is in the basement or part of a double storey extension, then you should expect the costs to be far higher than a standard single storey kitchen extension. A basement extension will cost around £3,000 / square metre for the labour. You should expect to pay an additional 50% of the single storey build if you are carrying out a double storey extension.

Think of the long term investment and don't scrimp on costs to save in the short term. For example, you may decide to keep the kitchen extension small to save money. However, in the long run you might wish you had extended further. It's worth looking at the incremental cost and whether you could stretch your budget or indeed delay the kitchen extension until you can get exactly what you want.

Don't scrimp on a good quality builder. Although you want to keep the labour and build costs low, if the quality of work is poor then you may need to invest more in the future to fix poor workmanship.


If you are thinking about a kitchen extension in the near future and need some help finding an architect or designer, we can match you with the most suitable ones for your project.

Find an architect


Published: November 4, 2021


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