gianni botsford revitalizes london cottage with norman foster extension

gianni botsford architects completes reciprocal house

Gianni Botsford Architects tucks the Reciprocal House behind a Victorian pub in a quiet Hampstead mews. The London family home replaces a dilapidated 1860s cottage while restoring a single-story 1969 extension by Foster Associates (now Foster + Partners), complementing its industrial character with a reciprocal new volume. Defined by a steel truss structure, concrete blocks, and large-span aluminum-framed glazing, the original extension informs the new intervention’s minimalist language, materiality, and form.

The new addition reimagines the cottage’s roof profile through sharp, geometric elevations, while a perforated aluminum mesh cloaks the facade. Its soft copper-brown tone evokes the memory of the demolished structure while providing shade, privacy, and a visual connection to the surrounding trees.‘Our response to this sensitive and overlooked context is led by the notion of local adaptation,’ explains Gianni Botsford. Throughout, passive strategies have also been implemented to ensure that the house has minimal environmental impact.

a perforated aluminum mesh cloaks the facade | all images by Schnepp Renou unless stated otherwise

aluminum elements intertwine with recycled brickwork

The project’s name, Reciprocal House, reflects its conceptual approach establishing a continuous dialogue between old and new. Gianni Botsford Architects’ intervention equalizes the architectural stature of the 1960s extension and the contemporary addition, creating a unified yet distinct composition that embraces natural views and a raw industrial aesthetic. Landscaping also embraces recycled bricks from the demolished cottage, emphasizing embodied memory while rooting the project in its past. Above, a vast roof terrace complements the volume’s transparency and immerses residents in the surrounding canopy of mature trees, connecting architecture and nature.

Inside the four-story house, the London-based architects introduce a series of locally fabricated aluminum elements, including a striking spiral staircase — a sculptural focal point — kitchen units, wardrobes, and bathroom fittings. A 2-meter-wide circular rooflight above the staircase floods the levels of the space with natural light while doubling as a ventilation shaft to enhance the home’s passive cooling strategy. Openness and flexibility are further prioritized with the layout, with the ground floor featuring a connected kitchen, dining, and living space. These flow seamlessly into the restored Foster + Partners extension, originally designed for entertaining and housing a grand piano. The upper floors, meanwhile, host three bedrooms and a roof terrace, and a basement studio benefits from tall, light-filled wells that draw daylight into the underground space.

Gianni Botsford Architects completes Reciprocal House

passive strategies ensure a minimal environmental impact

From form to function, sustainability drives Gianni Botsford Architects approach. Materials with high thermal mass, such as exposed concrete, temper indoor temperatures naturally, while enhanced insulation and airtight construction reduce heating needs. The design eliminates gas reliance entirely, with an air-source heat pump providing underfloor heating and an EV charger installed in the front lightwell. Rainwater and greywater recycling systems further minimize water use, while green roofs reduce runoff and enhance biodiversity. The spiral staircase and opening rooflight work in tandem to create a stack effect, allowing warm air to escape in summer and promoting natural ventilation throughout.

the family home replaces a dilapidated 1860s cottage while restoring a 1969 extension by Foster Associates