Sky Lantern House is an innovative full house refurbishment and extension project in South London. The project’s success lies in the collaborative approach to embracing innovative materials and construction complexity. A radical project evolved which explores the core architectural principals of light, form, and craft, but has been delivered with value and environmental responsibility.

With a handsome south-facing street frontage that remained untouched for heritage reasons, solutions to maximise daylight from the north were explored to lift the gloomy interiors of the house. Early studies explored how simple stacked massing, inspired by the existing variable sized dormers, could be added to the rear without it impeding on neighbouring amenities. The exterior simplicity created interior spacial complexity with differing floor levels, ceiling heights and room depths demanding bold structural and material solutions in order to create uncluttered, joyful spaces.

A bold series of stacked volumes cascades into the rear garden. The upper box defines a double height space that connects the timber-lined study with the social activity of the home. Clad in vertical glass planks it evokes the ethereal quality of a floating ‘sky lantern’ at night. Slender steel posts are discreetly encapsulated within the cavity of back to back glass channels, allowing the lantern to seemingly float unsupported, whilst providing solar and thermal control. The textured translucent finish protects neighbouring views, a critical point for planning consent, whilst bringing clerestory light into the deep plan.

A second void is carved out of the interior with a replacement staircase. Landings have been reshaped to create a dramatic three storey triangular void that permeates natural daylight into the heart of the house. The existing heavy stair structure is replaced with an elegant folded steel plate sandwiched in oiled Douglas Fir planks. Timber was used extensively inside to contrast with the cool, high performance exterior.

The ground floor is opened up front to back to provide large flexible family spaces with a double aspect of views and natural light. Integrated joinery adds storage and clever functionality. Fold away workstations for the children support flexible family living at the social heart of the house. At first floor, a large master bedroom is upgraded with generous walk-in wardrobes and a luxurious master bathroom ensuite overlooks the lush sedum living roofs.

Environmentally the project is designed beyond required thermal performance, achieving a 27% improvement over regulatory U-values (heat loss calculations). The glass facade system is readily demountable for re-use or recycling. Careful attention was also given to co-ordinated landscape design by enhancing local bio-diversity with increased areas of garden planting and an extensive green roof.