Before we give you some up-to-date estimates to guide you with your kitchen extension project, there are some factors you’ll need to consider when working out the cost… The size of your extension, for example, the materials you plan on using and the amount of glass you want in the build to name a few.
The final price will be affected by every choice you make when extending, and that’s before you get into additional costs such as planning permission, engineer fees, surveys and more.
However, having a grasp on how much an extension costs is important to allow you to decide whether its viable option to be building an extension at all.
To help, we’ve created an easy reference which offers some approximate figures you can use to start to consider your project. Please bear in mind that these figures probably won’t match up perfectly with your builders quotes and will differ depending on where you live in the UK, but they should at least give you a good indication on what costs to expect.
Before making any financial commitments, take some time to consider whether an extension is right, or financially viable, for your property.
If this house is your ‘forever home’ then an extension is a no-brainer compared to the hassle of moving house. Financially, opting for an extension means you’ll save on stamp duty, moving costs and solicitors fees which aren’t recouped by adding value in the same way as your extension.
If you are planning on selling up in the future, you’ll need to ensure that the extension adds more value to your home than it costs to build. Speak to local estate agents and research ceiling prices in the area before making the decision to go ahead.
As a rough guide, most extension projects will cost around £1,350-£2,250/m² of new internal floor space. So a 25m² kitchen extension would come in somewhere between £35,750-£56,250, plus VAT
Not the most accurate of estimates I know, but the cost will vary greatly depending on, among other things, the materials you’re going to use, how and where it is going to be built and who’s going to build it. The £1,350-£2,250 price, however, is a very good range of pricing based on averages.
Let’s drill down on some factors that can affect the cost of your project, including:
Here are some example costs you might need to factor in:
If you’re planning on building a fairly straightforward, rectangular, single storey extension you should allow for around £1,250-£1,650/m². This price will vary depending on where abouts in the UK you live and the standard of build you opt for.
In more affluent areas of the UK such as London you could easily be paying £1,700-£2,500/m² meaning an 8x4m kitchen extension would cost between £43,000-£80,000.
For an excellent finish you can typically expect to pay 40% more than a standard finish.
A typical two storey extension won’t cost that much more than a single storey extension, at around £1,350-£1,750 per m².
Both options will require foundations, walls and a roof so by opting for a two storey extension you are only adding extra height to the walls, floor joists, windows and some additional stud work to form the walls on the first floor.
Obviously if you are planning on creating additional bathrooms or fitting out your additional bedrooms with high end furniture this will increase the overall price but for the shell of the extension, the difference between a single and two storey build is pretty negligable.
For a traditional timber frame build, as far as materials go, the cost of timber is lower, but not by much. And whether you opt for timber or brick & block construction, the rest of the build costs will be the same.
Traditional timber frame construction
Structural Insulated Panels (SIPS) construction
Modern methods of timber construction, such as structural insulated panels (SIPS), might cost more to begin with, but cost-savings will come from speed of construction (reduced labour costs), especially when it comes to insulating your extension. Also, because the structure is quickly weatherproofed, plumbing and electrical systems can be installed earlier than in brick buildings and the internal finishes can commence at the same time as the external finishes are being applied.
The exterior finish of your new extension is equally as important as the light and space you create inside. While you’ll be experiencing more of the interior finishes than the exterior, a high-spec’d, well-designed and well-built extension not only adds considerably more value but will give you more pleasure than a plain box stuck to the side of your house.
When considering your choice of external finishes, it’s important to understand that the external wall of the extension is purely decorative and acts merely as a weatherproof barrier to the internal supporting structure. This means, for example, that the extension can have blockwork structural walls but be finished in timber or composite cladding.
Your choice of cladding on the extension will obviously affect the overall cost. Timber cladding over the frame will be significantly cheaper than a brick envelope enclosing it. This also takes less time to install than brick.
Most extensions will be subject to the standard rate 20% VAT on materials and if you’re using a contractor to carry out the build then you will also be charged VAT on labour costs.
If you use individual tradespeople who are not VAT registered you can save the 20% VAT on their labour, but you will still have to pay VAT on materials.
Some extension projects are eligible for VAT relief, such as work to a building that has been unoccupied for at least two years.
To benefit from VAT relief from the above, you must use a VAT registered builder — you can’t reclaim the VAT yourself.
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