Double O Studio tops trefoil-shaped concrete house with rooftop pool

Double O Studio has designed Trefoil House in Aroeira, Portugal, as a series of overlapping concrete shapes topped by a long swimming pool.

Set on a sandy site amongst pine trees close to the Atlantic Ocean, the two-storey house has an unusual geometry that gives it its name.

Drone view of pool for Trefoil House in Portugal by Double O Studio
The swimming pool runs along the rooftop. Photo by Marco Antunes

The ground floor is arranged around a hexagon-shaped hall, with a kitchen, living room and dining room in adjoining, tessellating hexagons. Between the rooms, three concrete rings shelter circular terraces.

On the first storey, three more hexagon-shaped rooms contain individual bedrooms with offset bathrooms that cantilever over the footprint of the building below to create a broken circle.

Concrete patio of Trefoil House by Double O Studio
Curving concrete walls define ground floor terraces

On the first floor, a stairway leads from the atrium into the space above one of the circular terraces and to a split level roof that is bisected by a long, narrow pool.

A rooftop terrace for enjoying the sunshine sits on the lower side, while the raised half is a platform for solar panels.

Rooftop swimming pool of Exterior of Trefoil House by Double O Studio
The pool looks out over the pine trees

Double O Studio said the design came from finding a way to include as much outdoor space as possible without impinging on nature by building a house with an expansive footprint.

"One of the design intents was to raise ground as roof and insert the space of the house under it while keeping the terrain as untouched and natural as possible," explained the studio.

"The house produces its own introverted world facing the sun."

Interior of Trefoil House
Trefoil House is arranged around a hexagonal central square

Corrugated edges on the curving concrete walls, which were all cast in situ, create visual interest in the patios as the sun passes overhead and the shadows change.

The pool crossing the central atrium creates a triangular skylight in the middle of the house, bringing light and air to the rooms.

Concrete walls Trefoil House by Double O Studio
Some of the concrete walls have a corrugated edge

There are few windows on the outside. Instead, Double O Studios inserted strategically-placed walls of glazing on end walls.

"There are no privileged vistas, no distant horizon and no strict physical boundaries to address, no front, back or side divisions," said Double O Studio.

"The sky is the site's only vantage point."

Exterior of Exterior of Trefoil House by Double O Studio
The concrete house has few external walls

All the homes, walls and its internal and external staircases are made of concrete, which has been left exposed throughout the house.

The architecture practice had the photography taken while Trefoil House was still empty to focus on how the project's material and form interplay with sunlight.

Bathroom of Trefoil House by Double O Studio
The bathrooms are alongside concrete lightwells

Double O Studio was founded in 2012 by Olivier Ottevaere and Elsa Caetano.

More concrete homes with stand-out swimming pools include Art Villa in Costa Rica by Formafatal and Refuel Works, and Casa B by Architrend Architecture in Malta.

Photography is by Fabio Cunha unless otherwise stated.


Project credits:

Architect: Double O Studio
Team: Olivier Ottevaere, Elsa Caetano
Local architect: Marco Antunes
Structural Engineer: Joao Silva
Contractor: CS Construtora

More images and plans

Plans for Trefoil House by Double O Studio
Ground floor plans
Plans for Trefoil House by Double O Studio
First floor plans
Plans for Trefoil House by Double O Studio
Roof plana
Plans for Trefoil House by Double O Studio
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Plans for Trefoil House by Double O Studio
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Plans for Trefoil House by Double O Studio
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Exterior of Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Rooftop pool of Trefoil House
Exterior of Trefoil House
Interior of Exterior of Trefoil House by Double O Studio
Interior of Exterior of Trefoil House by Double O Studio
Interior of Exterior of Trefoil House by Double O Studio
Exterior of Exterior of Trefoil House by Double O Studio
Staircase of Trefoil House by Double O Studio
Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Exterior of Trefoil House by Double O Studio
Concrete staircase of Trefoil House by Double O Studio
Doorway of Trefoil House by Double O Studio
Staircase of Trefoil House by Double O Studio