
As a general rule, building a new building is easier than trying to do surgery on an existing one, because you never know exactly what you're going to find when you start the latter. But there are instances where surgery is necessary.
According to Bloomberg, developers in London are becoming increasingly interested in the airspace above existing buildings, and it supposedly started because of some policy changes:
In 2020, then housing minister Robert Jenrick introduced reforms that relaxed rules to add airspace builds above existing buildings. Owners can now construct additional residential stories to either expand their own dwelling or to create new units altogether without going through full planning permissions, which are often a long and costly process. This was part of a broader set of reforms to boost housing supply, and the current Labour government has not shelved these changes.
Here's an example site listed for £150,000:
The site currently comprises the roof and airspace above a 3-storey mixed-use residential-led block (Block B) within The Glassworks Development.
The existing development was constructed in 2017 and comprises 23 residential apartments plus ground floor commercial space, all of which are sold off on long leases.
I had an old boss who was very interested in this idea. For him, it was "free" land and a way to further extract value from an existing real estate portfolio. Of course, it's also a way to build new homes in already built-up cities.


