Recent research has shown that £6.5 billion was added to British house values in a year by extensions or other alterations.

Real estate experts Savills have shown that in a 12-month period up to March, around 220,000 property owners elected to upgrade their homes. On average, this activity was estimated to have boosted house prices by £30,000 each. This figure shows that significant value can be added to a building through a home extension, with Cheshire being a county in which high value houses are in particular demand. Lucian Cook, who heads residential research for Savills in the UK, has said:

“The cost of taking the next step up the housing ladder and the difficulties in acquiring the mortgage finance to do so appear to have encouraged a significant proportion of owner occupiers to extend or alter their existing home.”

Cook has suggested that alterations in policy may have had some influence on the behaviour of the public. He has singled out stamp duty changes and the impact of a review about the British mortgage market as being of possible significance in this regard.

The research in question has focused attention on extensions in London to a degree. However, it has made the general assumption that an extension can add about 10% to the value of a house. Further, it has looked at developments in areas outside the capital, including Cambridge, St Albans, Guildford, and Maidenhead.

The research has shown however, that more extensions have been carried out in markets with a high value. This has been accounted for in part as being the consequence of more money being available than elsewhere.