Skip to main content Skip navigation

House Extension Cost Calculator

Are you looking for more space or thinking of buying a house and extending it yourself? Well before you go dreaming of sky lights and kitchen islands, take a look at our House Extension Cost Calculator below to determine how much you may expect to pay for the labour costs in England and Wales.

Bear in mind you will also need to budget for materials and other costs such as planning permission, but it should hopefully help you with your first step.

We’ve also given a very rough estimate of how much an extension could add to the value of your property. This potential value is based on the average asking price per square metre of property in different areas and should be used as a rough guide only. Our experts say once a house is a certain size there can be a price ceiling that potential buyers are willing to pay and so an extension may not necessarily lead to an increase in value, but it reveals the wildly different values of a square metre across England and Wales so it could also show you where you could get more for your money if you’re thinking of moving.

Simply add your postcode below and select the size of extension.  

How much does it cost to add an extension to your home?

House Extension Cost Calculator

Size of extension

Tips to cut the cost of your extension

  • Choose a simple design – the most cost-effective floor plan is square (future buyers will appreciate neutrality, too)
  • Plan ahead as much possible
  • If you have time, consider being your own project manager 
  • If you have good DIY skills, do some of the more basic work yourself 
  • Hire someone to produce your planning and building regulations drawings for a fixed, all-inclusive price
  • Hire a reputable builder with proven problem–solving skills
  • If possible, find individual subcontractors who turn over less than the VAT threshold – they won’t charge you any VAT on labour
  • Buy off–the–shelf where you can  
  • Buy second hand where possible
  • Avoid complicated groundworks

Extending or converting areas of your house can be a great way to both improve your own enjoyment of your property and increase its value too. With a bit of savvy and a lot of careful planning, you could be well on your way to your dream home in no time. 

Need some inspiration? Take a look at these four homes with EPIC extensions.

Related articles