More than 40,000 new homes could be built on London’s roofs

New research conducted by global property consultancy Knight Frank, has found that as many as 41,000 new dwellings could be built in central London using rooftop development space, without altering the iconic skyline.

The study, which uses the latest geospatial mapping software, highlighted that 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 by using the ‘airspace’ above them”. In response, Knight Frank has developed ‘SKYWARD’ – a method to systematically analyse the potential of each building.

SKYWARD analyses 3D spatial data from the Ordnance Survey, cross referencing Land Registry data to assess ownerships and Historic England data to filter out listed buildings.

Representing the sheer scale of the opportunity, some 23,000 buildings could be suitable for rooftop development in Zones 1 and 2, and the volume of the unused plots across the same area is equivalent to eight Burj Khalifa towers (830m high), crucially without the corresponding impact on London’s skyline.

Charles Dugdale, Residential Development partner at Knight Frank commented: “Skyward is a fantastically powerful tool for identifying development opportunities to unlock thousands of new homes in London and ease housing supply pressures, particularly in those areas where availability of land is becoming increasingly rare. It also has the potential to add an objective approach to planning decisions on a semi-permissive basis.”

Ian McGuinness, Head of Geospatial at Knight Frank, commented: “Using 3D mapping technology the findings of this analysis can be related to other geographies easily, including to client land ownership portfolios. We can now say where the opportunities are, how much value they unlock, and which land owners are best placed to drive this transformation.”

The mapping product initially defines each contiguous block by its maximum height, then excludes unsuitable buildings (listed buildings and those where historic airspace rights are recorded by Land Registry), before extruding all remaining buildings up to the maximum height. Only those that can be extended by a minimum of 3 metres are deemed to be potential SKYWARD developments.