London’s housing crisis could be alleviated by the development of tens of thousands of new homes on its rooftops.
The study, which used the latest geospatial mapping software, suggested more than 28 million sq ft of potential additional residential floor area could be developed, with this airspace having a potential value of £51 billion.
Stimulated in part by the 2017 Housing White Paper, the research project aimed to identify the extent of the government’s pledge to seek out opportunities for higher-density housing in urban locations, particularly where buildings can be extended upwards.
Knight Frank developed SKYWARD, which analyses 3D spatial data from the Ordnance Survey, cross-referencing Land Registry data to assess ownership and Historic England data to filter out listed buildings.
Only buildings that can be extended by a minimum of 3 metres are deemed to be potential SKYWARD developments.
As an example, it identified airspace over 42 Reeves Mews in Mayfair as suitable for development of an additional floor. Planning history confirms in 2014 Westminster Council approved reconfiguration of the building to provide two self-contained flats, including an extension into the roof space on second floor plus a terrace area.
In total, the consultancy estimated that around 23,000 buildings could be suitable for rooftop development in Zones 1 and 2.
The volume of the unused plots is equivalent to eight Burj Khalifa towers (830m high), but without the corresponding impact on London’s skyline.
The figures intentionally underestimate the potential opportunity above existing buildings which have been considered by others.
For example, WSP and UCL estimated that 630,000 residential homes could be created above London by building six storeys above existing municipal buildings.
Meanwhile, planning consultants hta considered a series of building typologies across Camden that could reasonably accommodate one, two or in some cases three additional floors irrespective of the heights of neighbouring buildings. hta then extrapolated its study area of Camden across the wider London area to conclude 179,126 new homes might be possible on this basis.
Knight Frank said while this may be possible, it would “unquestionably have an impact on the street scene and would need to be judged on a case-by case basis by planners”.
It claimed the SKYWARD tool is intended to identify opportunities that would not negatively impact the street scene.
“Indeed in many cases we would expect the development to enhance the street scene, for example by forming continuous ridge lines along residential terraces,” it added.
Airspace is becoming somewhat of a buzzword among property developers and investors, but it’s still a fairly new concept.
Leaders in the field are keen to educate people about what exactly airspace is and how construction works.
Apex Airspace, an authoritative voice in the airspace market, has got six projects ready to go worth in the region of £30 million, which should deliver 82 homes.
DealMakerz thinks the government’s endorsement of rooftop housing could make it a huge opportunity for the property industry over the next few years.