Reciprocal House by Gianni Botsford Nods to Norman Foster’s Work

Located in Hampstead, Reciprocal House replaces a dilapidated 1860s cottage and incorporates a 1969 extension by Foster Associates. Gianni Botsford Architects designed the four-storey home, maintaining the industrial character of Norman Foster’s single-storey structure.

The existing extension, a mix of steel trusses, concrete blocks, and aluminium-framed glazing, informed the material palette for Reciprocal House. The design preserves the “exemplary” spirit of the Foster Associates’ extension.

This Hampstead property accommodates kitchen, dining, and living spaces on the ground floor, three bedrooms, and a roof terrace upstairs. A 3-meter tall lightwell illuminates a basement-level studio room.

The ground floor connects to the Foster Associates’ open-plan room, originally meant for entertaining. Gianni Botsford designed highly crafted aluminium elements for the interiors, including the staircase, kitchen units, and bathroom fittings.

The aluminium elements, all made in East London, can be seen throughout the property, providing modern detailing to the existing structure of exposed bricks.

The new house’s roof profile and distinct angled elevations echo those of the original cottage. A two-meter diameter circular rooflight over a spiral aluminium staircase connects the three main floors, providing natural ventilation and a connection to the outdoors.

The facades feature perforated aluminium mesh in a copper brown hue, preserving the memory of the original house while providing privacy and solar screening.

Botsford explained that their design depends on “local adaptation” to offer “privacy for the occupants of the house and neighbours, long views out to the borrowed landscape of back gardens, access to sunlight and daylight, acoustic separation, and security.”

Numerous study models were used to investigate the new house and Foster Associates extension relationship, promoting a design approach that considers the house and surrounding landscape, especially the 56-square-metre roof terrace with mature trees.

Materials from the demolished original house were used in the landscaping to minimise environmental impact and embody memory.

The house’s design incorporates passive solutions like window orientation for maximised daylight and natural ventilation. A spiral stair serves as a vertical ventilation shaft, with an opening rooflight to expel warm air.

To keep the house cool without active cooling, high thermal mass materials like exposed concrete are used. Conversely, enhanced thermal insulation and air tightness minimise space heating needs. Heating is provided by an acoustically attenuated air source heat pump and underfloor heating.

Botsford explained that the complex form prompted a concrete structure, leaving it exposed to “reduce the use of finishes, temper the light, and benefit from the thermal mass.”

The house is all-electric, eliminating the need for gas, and features low-flow water fittings, a grey water recycling system, and rainwater recycling with green roofs for water conservation.