How Much Does A House Extension Cost


Building extensions can be a daunting task as you have to get a clear insight into the extension rules, services as well as the cost, which is often very tricky to get. Getting a clear idea about the cost of extensions will not only help you in deciding your budget but will also help you plan further.

So, how much does a house extension cost?

According to the builders in Cheshire area, the cost of building an extension depends on certain factors including the type of extension you’re planning for, the location, extension rules etc.

Usually the small and single-storey extensions are cheaper than double-storey, kitchen and bathroom extensions. Also, the location is a very important deciding factor while determining the cost. For example, if you live in London or a nearby area, the cost of extensions will be fairly higher than any other part.

Below is a rough estimate of the cost of extension in different areas :

Single storey extension

The average single-storey extension cost ranges from £1,350 to £1,950 per meter square. This range will get increased for London and the nearby areas, it could be anywhere between £1,800 and £2,300 per meter square.

Also, the prices will also vary depending upon the quality of extensions. Generally, the high-quality extensions will cost a little more than the low-quality ones.

Overall, a single-storey extension in London will cost you around a minimum of £40,000 and a maximum of £67,000.

Double Storey Extension

If both the storeys are of same size, then you can estimate an approximate cost by adding 50% to the building cost of one storey extension. It is as simple!

Suppose, the single-storey cost is £40,000, then double-storey extension cost will be

£40,000 + 50% = £60,000

Again, about 10% vat will be added and these prices will be a bit high for the London and South East areas.

Kitchen And Bathroom extensions

Kitchen and bathroom extensions are a little bit tricky. This is because you need to take several things into account such as permissions, plumbing and other fittings.

Depending upon the type of your extension, you can take a minimum value of £5,000. This price will vary according to what you actually want in your bathroom such as adding showers, toilets, WCs etc.

Kitchen extensions are obviously pricier than bathrooms. You can take a minimum value of £10,000 for a low to middle range kitchen. Again, the price will go up if you’re planning for a fancy and modern kitchen.


The average extension cost outside London can fall between £1,200-£1,500 per meter square.

For the South East and London, this cost will go up around £1,500-£2,000+ per meter square.

For a double-storey extension, add 50% to the cost of your single-storey extension. Similarly, add £5000 – £10,000, if you’re planning to add a bathroom or kitchen. Moreover, consider other factors like plumbing, kitchen fittings, adding windows /doors etc while estimating your cost.

To get a more precise calculation, it is recommended to get at least 3 to 5 quotes.


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BDC 319 : Aug 2024