Cantilever building

5 cantilevered Grand Designs

These outstanding homes appear to defy the laws of physics

By Hugh Metcalf |

A cantilever building is one where part of the structure protrudes beyond the rest. While they offer the illusion of defying gravity, most cantilevers have a point of connection further back in the building, and another support column closer to the cantilevering length.

Architect Frank Lloyd Wright is considered a pioneer in cantilever buildings, Fallingwater in Pennsylvania being his most famous. Built between 1936 and 1939, the daring design was a cause for concern for the contractors, who added extra steel reinforcement to the cantilever. Even then, a 1995 report found that the cantilevers were worryingly close to failure, and extra support was added. But cantilever engineering has come a long way since then.

How far can a cantilever extend? You’ll need to consult a structural engineer to answer that question, but the one-third rule is commonly applied – for every foot of supported joist, there should only be one third of that amount as overhang.

Adding a cantilever is a clever way to maximise space on a small or awkward plot. Overhangs can also help protect buildings from water damage in flood-prone areas, create space for parking, or simply be used to frame beautiful views in remote locations. It’s an architectural technique used in some iconic Grand Designs homes, as shown below.

1. Patrick Bradley’s shipping container home

When constructing a new home on his parent’s land in County Derry, Northern Ireland, architect Patrick Bradley opted for metal shipping containers to create a low-cost cantilever building. The house is essentially two containers set one on top of the other, at right angles.

The upper storey overhangs the ground floor at both ends and includes a balcony surrounded by steel fins. They serve to prevent too much solar gain overheating the living space. The containers were insulated and weatherproofed to prevent the build-up of moisture that might cause the metal to rust.

The exterior of a cantilever building created by placing one shipping container on top of the other.

Photo: Aidan Monaghan

2. Natasha Cargill’s periscope house

Natasha Cargill’s Norfolk Grand Design is most recognisable for its symmetrical cedar-clad boxes. They both extend beyond the ground floor and include balconies providing views over the River Tud valley.

The timber-clad periscope designs are at slightly different angles, allowing more light to reach the thermal-mass staircase and giving each wing a different outlook. A 6kW array of solar panels on a sedum roof provide electricity, and to stop the soil pushing the semi-submerged building down the hill, gabions filled with local flint line the building’s edge.

The exterior of a house with symmetrical cantilever first floor wings. The top floor is clad in cedar boards.

Photo: Darren Chung

3. Carl and Mary’s glass house

Carl Turner and Mary Martin’s self-build in Brixton consists of a stack of three cantilevered glass-clad rectangles. The house takes up the entirety of the plot they sub-divided from the original house on the site. Its design makes efficient use of the space with a small wildflower garden on the second storey cantilever to bring greenery to the space.

They have a cutting-edge system that sends excess heat from the PVT panels down to the heat pump to improve its efficiency, and they have a tank to collect rainwater for the WCs, washing machine and outdoor taps. The house is also super-insulated and wrapped in an airtight membrane to stop heat leaking out.

cantilevered glass house in brixton from grand designs

Photo: Rachel Whiting

4. Colin and Adele’s curvy cantilever house

Colin and Adele Offland wanted to incorporate the curves and cantilevers of the American Art Deco beach hotels they had seen in Miami into their vision for a Scandinavian-inspired home in South Manchester. Swedish architect Vasco Trigueiros designed a three-storey house with rounded corners and two timber-clad upper levels cantilevered over a ground floor incorporating big expanses of curved glass.

The planning process took two years and included changing the proposed timber frame to a steel one to provide the big, open spaces the couple wanted. Costs spiralled as the labyrinthine steel framework was adjusted to avoid having to install a column that would spoil the drama of the cantilever. Once the challenging build was completed, Vasco called it ‘a beautiful monster’.

Exterior of Colin and Adele's Manchester cantilever house as featured on Grand Designs

Photo: Andy Haslam

5. Geoff Wood’s flood-proof house

The threat of rising sea levels along the banks of the River Blackwater in Essex didn’t deter Geoff Wood from making his home on its windswept estuary. His Grand Design is surrounded by a bund wall, designed to keep out water. But should this be breached, the living areas and bedrooms on the cantilevered first floor – 4.5m above ground – will remain dry.

The plans were drawn up by Richard Coutts of Baca Architects, a practice specialising in climate-resilient properties such as the amphibious house in Buckinghamshire, which was designed to float in the event of a flood.


Photo: Jefferson Smith

Discover more about cantilevered buildings in this video by construction video channel, The B1M: