Applications to build or extend basements in residential properties have increased by 9% between 2013 and 2015, according to Direct Line research.
In 2015 at least 1,968 planning applications were made to local councils in Great Britain, of which around three quarters (74%) were granted.
A huge proportion (75%) of all basement planning applications in 2015 were made in London, compared to regions like Wales and Yorkshire which received less than 1% of planning applications.
In the Capital there has been an 11% increase in planning applications for residential basements, up from 1,348 in 2013 to 1,497 in 2015. Second to London is the South East, which has seen an 8% increase to 165 in 2015. When combined, London and the South East account for the vast majority of basement applications in Britain in 2015.
There is a clear relationship between the regions which are seeing increases in applications to build basements and the average house price in that region. London has the highest average house price of any British region (£457,759) and the largest proportion of residential basement applications (75%). Property prices are so high for those living in London that extending existing properties may be a more cost effective, less disruptive alternative to moving home.
The regions with the lowest average house prices like the North East (£121,085) and Scotland (£134,625) had two of the smallest shares of residential basement applications in Great Britain (0.4% and 0.6% proportionately).
In terms of successful applications, the North West (90%) and West Midlands (87%) saw the highest proportion of applications approved by local councils. All planning departments across British regions approved at least two thirds of residential basement applications in 2015.
Nick Brabham, head of Direct Line SELECT Premier Insurance, said: “With house prices on the increase, especially in places like London and the South East, it makes sense that British homeowners are doing everything they can to their properties in order to maximise space and value. Over the past twenty years loft conversions have been a popular choice for extending a property and now a growing number of property owners are building downwards to create additional space in a basement. This can be ideal for those living in towns and cities where extending outwards is impossible due to living in terraced and semidetached properties, or where large above ground extensions are prohibited.
“If you are considering building a basement, make sure you get planning permission from your local council. Basement works can sometimes cause disruption to surrounding properties, so make sure your neighbours are aware. You may even need written consent from them if you share a wall.
“As with any major building work, your insurance provider needs to be informed as it affects the structure of the property you insure. There are additional implications if you are adding bedrooms too, so it’s worth having a conversation with your provider before undertaking any expensive works.”