The new properties, designed by HTA Design LLP, are being developed on top of, next to and in between two existing residential buildings.

Adston has been chosen as the design and build contractor for the development.

The scheme includes ‘bookends’ at each end of the existing buildings, a new central core connecting the buildings, and a double-storey rooftop extension.

The new homes — which will be built off-site using modular methods — will be a mixture of one- and two-bedroom apartments, with 24 being offered at London affordable rent, and the remaining six at Southwark Council’s social rent.

The property will be highly insulated, water and energy efficient, and the external wall construction of the new flats will be non-combustible.

The year-long project will use a blend of light gauge steel-based (LGS) modular construction on the rooftop units and LGS panels for the bookends and infill, and is set for practical completion in February 2022.

Initial works will remove the existing pitched roofs before a structural steel exo-skeleton will be positioned on top of the existing building. 

Once this is in place, the modular apartments will be installed onto the rooftop. 

It is expected that the creation of new homes could generate a balance sheet leverage of approximately £4m, which could be used to fund additional new homes.

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Arshad Bhatti, CEO at Apex Airspace, said: “Our collaboration with LSHA demonstrates our ability to unlock a previously untapped supply of affordable housing in London and be able to deliver policy-compliant rented accommodation in partnership with local authorities and housing associations. 

“At Apex, we set out to make a tangible difference to the residential landscape in London and to address the UK’s housing shortage. 

“Our pioneering model is a blueprint for other councils and housing associations to follow suit and adopt innovative solutions to address the lack of affordable housing in London.”

David Rainey, client relationship manager at Adston Construction, commented: ‘‘Antony and Roderick House is a fantastic project to be involved in and Adston is delighted to be appointed by Apex Airspace for the design and delivery of these new homes. 

“This is an innovative and new direction in the expansion and extension of existing buildings, and we believe the first of many sustainable residential developments of this type.’’

Mark Jackson, chief executive at LHSA, said: “It’s great to see works begin on these much-needed affordable properties in Bermondsey. 

“Apex’s development methods are both innovative and efficient, which is what the housing landscape in London desperately needs.

“As a housing association, we need to ensure we are maximising our existing stock in the capital."