London homeowners can make a whopping £156,000 if they invest in a 30 metre extension on their home, research from Barclays with Countrywide has revealed.

The Barclays Mortgages Home Improvement report for 2015 found that even when building costs are taken into account, homeowners in the capital can vastly increase the value of their homes – giving them the £156,000 return.

The index also found that homeowners make hefty returns in Brighton (£69,000) and Winchester (£61,000), although the least profitable to build a 30 metre extension would be in Hull, where homeowners would lose out by £17,000.

The average return for a UK homeowner would be £14,000.

Andy Gray, Barclays managing director of mortgages, said: “Clearly our research shows that some of these improvements can add value. But it is important to note this is not the case everywhere.

“Also, many people decide to improve their home simply out of necessity, perhaps due to a growing family, and adding value is not a primary consideration.

“Each homeowner should research the best option for them, taking into consideration the home improvements they would need to make, how much this would cost and investigate whether moving property may actually be the better option.”

UK homeowners who stay in their properties for 14 years on average said they have added a collective £164bn to their value of their homes through improvements.

More than two in five (42%) wanted to see a designer kitchen installed, while second and the third most desirable improvements were adding an en-suite bathroom (38%) and swimming pool (29%).

In terms of what homeowners were planning next nearly half (45%) wanted to repaint their interiors, while a quarter (25%) planned to install new carpets.