Extension Calculator

Will an extension increase the value of my house?

We’ve used ONS data on property prices per square metre to help you find out what extra floor space could be worth in your area.

The value of an extension will depend on many things that we haven’t allowed for here, like the quality of construction, what type of room it is, and the exact location of the property within your local authority. This calculator uses average values for houses across local authority areas, so should only be used as a guide.