The average extension is around 24m2, which is typically considered medium in size. A general costing for a 24m2 extension starts from £20,000 but can range to over 5 times this amount. The floor size can still take many forms and an extension cost is very much dependent on the style and complexity of the extension that you have. For instance, one 24m2 extension may cost a dissimilar amount to another of the very same size due to its entirely different style or layout as well as what the extension will be used for. Below outlines what you can expect to pay for a 24m2 extension.

For ease of comparison, we’ve compared the prices of three c. 24m2 extensions across four of the most popular extension types; single-storey, double-storey, side extensions, and rear extensions. On average, any sort of extension could set you back between £20,000 to £125,000 but as we mentioned, this varies massively depending on the type of extension you choose, as well as its size. As these extension costs are all for c. 24m2 extensions, you’ll be able to see things more comparatively.

Single-Storey Extension Cost

Arguably the most popular extension type and used to augment the space of typically a kitchen or living room on the first floor of a home. For a medium-sized single-storey extension, you’re looking at between £35,000, all the way up to £50,000 for the most premium of finishes.

Double-Storey Extension Cost

For an extension split across two floors of the same rough size, you’re likely going to be looking at a fair bit more. However, as space is spread across two floors, its impact will feel far greater. It’s worth keeping in mind that 24m2 would be considered small for a double-storey extension but they would start from £42,000 and go up to about £80,000 for a premium offer.

Side Extension Cost

This kind of extension is a very common choice for homes with plenty of space on one or both sides of the property. Again 24m2 would be on the smaller side of medium here but prices start from £20,000 and could double to £40,000 for a slightly larger or more premium extension.

Rear Extension Cost

If you’re planning on extending into your garden, then a rear extension is likely going to be ideal for you. At 24m2, you’re going to be getting a decent, medium-sized extension for your money. Prices for a rear extension of this scale start at around £25,000 and could go up to £40,000.

Factors affecting your extension cost

Your extension cost is largely dependent on the following factors:

  • Glazing requirements – you may want large doors or panes of glass. This is generally more costly than brick alternatives.
    Plumbing and services – the use of the room plays a large factor. If you require toilet facilities for example, this will boost the costs.
  • Condition of the existing area – if extra labour is required to clear the area and prepare the surface for a concrete base, this can add to the costs.
  • Level of finish – Specific finishes for luxury extensions will also ramp up the budget, for interiors such as polished concrete floors or large custom-fitted doors.

Why should I invest in a home extension?

A great question, and one that is really worth extensive consideration before going ahead with any new renovation project. Ultimately, you want a home extension to do two things. Firstly, add the sought-after additional space you desire and, secondly, increase the value of your home.

We provide a multitude of consultative services in a bid to help you extend your property in the right way. As building contractors in Surrey, we have a wealth of experience in delivering many different types of extensions, we’ve built garage extensions, porch extensions, wrap-around extensions, double-storey extensions, single-story extensions, and more. You can read more about our extension installations here. 

How do I decide what type and size of extension to go for?

Firstly, it’s important to identify what sort of space you are working with. If there is space to the side of your home, then it may make sense to opt for a side return or wrap-around extension. However, if you’re a bit more landlocked, then you may want to build up with a two-storey extension.

Surrey Building Projects Ltd can provide all of these different services helping you to extend your property in a way that suits you best. Some of the most popular extensions are adding an additional room with a conservatory or converting a garage to create additional interior space.

How do I get in touch and find out more?

At Surrey Building Projects Ltd we’d be delighted to help you price up your extension and take you from the initial planning stage all the way to execution. We take pride in advising our customers on every stage of the project ensuring that they are able to afford and accommodate the additional space. If you would like to find out more, then either fill out the form on our website, give us a call on 01276 583053 or send an email to

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