Concrete loggias overlook a courtyard at this social housing block in Paris, which French studios Francois Brugel Architectes Associes, H2o Architectes and Antoine Regnault Architecture have converted from offices.

Named Ilot Saint-Germain, the housing is located in two interconnected blocks previously owned by the Ministry of the Armed Forces in the city's seventh arrondissement.

To the south, a load-bearing stone building dating back to the 18th century faces the road, while to the north, an L-shaped, concrete-framed building from the 1970s hugs an internal courtyard.

Francois Brugel Architectes Associes, H2o Architectes and Antoine Regnault Architecture were tasked with transforming these former workspaces into 254 social homes, while adding a gymnasium and kindergarten for residents and the wider city.

Looking to highlight and complement the qualities of the existing buildings, the studios retained and restored their structures, drawing on their palette of pale stone and concrete for the gymnasium and kindergarten.

"The important thing was to work with the existing features, using the qualities of the original buildings and making them visible," H2o Architectes' Jean-Jacques Hubert told Dezeen.

"There is a real interest in thinking of the different ways in which these buildings, through the project, belong to the city," added François Brugel Architectes Associés's founder François Brugel.

An open courtyard space at the centre of Ilot Saint-Germain now also houses the gymnasium, which has a sunken concrete form with a wood-lined interior illuminated by clerestory windows.

On the opposite side of the central housing block, the kindergarten is contained in a matching pale concrete volume, finished with narrow vertical openings.

Both concrete volumes are topped by garden spaces designed by landscape architecture studio Élise & Martin Hennebicque, with ramps and steps providing access to the gymnasium's roof.

Ilot Saint-Germain's apartments are organised to minimise internal corridors and their interiors are kept minimal and flexible to allow residents to adapt them to their needs.

Facing the courtyard, the 18th-century block opens up with large, arched windows, while the 1970s block has been lined internally with loggias, providing each apartment with sheltered outdoor space.

"Each building offers specific layouts [that] result in a wide variety of typologies," said Hubert.

"Each user must find their place in the daily life of their home, the garden and the amenities," he added.

The use of pale concrete at Ilot Saint-Germain was guided by the stone and concrete finishes of the existing buildings, which have been complemented by dark wood window frames and pale metal balustrades.

Recently featured in Dezeen's Social Housing Revival series was another retrofit of a former military site in Paris, The Caserne de Reuilly, which saw h2o Architectes alongside six European practices adapt a former barracks site into nearly 600 homes.

The photography is by Jared Chulski.