The Double O Studio towers over a three-wing concrete house with a pool on the roof

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

The two-story house is located on sandy grounds amidst pine trees near the Atlantic Ocean and has an unusual geometry that gives it its name.

The pool runs on the roof. Photo by Marco Antunes

The ground floor is arranged around a hexagonal hallway, with a kitchen, living room and dining room in adjoining, tessellating hexagons. Three concrete rings protect circular terraces between the rooms.

On the first floor there are three more hexagonal rooms with individual bedrooms with offset bathrooms that protrude above the floor space of the building below to form an interrupted circle.

Curved concrete walls define terraces on the ground floor

On the first floor a staircase leads from the atrium into the room above one of the circular terraces and to a roof on two levels that is bisected by a long, narrow pool.

On the lower side there is a roof terrace where you can enjoy the sun. The raised half is a platform for solar panels.

The pool looks out over the pine trees

Double O Studio said the design came from looking for a way to include as much outdoor space as possible without compromising nature by building a home with a large footprint.

“One of the design intentions was to raise the floor as a roof and add the space of the house below while keeping the site as pristine and natural as possible,” the studio explained.

“The house produces its own introverted world facing the sun.”

The shamrock house is arranged around a hexagonal central square

Sidewalls on the curved concrete walls, all poured on site, create visual interest in the courtyards as the sun passes over us and the shadows change.

The pool that crosses the central atrium creates a triangular skylight in the center of the house that brings light and air into the rooms.

Some of the concrete walls have a wavy edge

There are only a few windows on the outside. Instead, Double O Studios put strategically placed glazing walls on the end walls.

“There are no privileged views, no distant horizons, and no strict physical boundaries, no front, back, or side divisions,” said Double O Studio.

“The sky is the place’s only vantage point.”

The concrete house has few outer walls

All houses, walls and the internal and external stairs are made of concrete that has been exposed throughout the house.

Ten architect-designed swimming pools to cool off at home

The architecture firm had the photograph taken while Trefoil House was still empty to focus on how the material and shape of the project interacted with the sunlight.

The bathrooms are next to concrete light shafts

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

Other concrete houses with outstanding swimming pools are Art Villa in Costa Rica by Formafatal and Refuel Works and Casa B by Architrend Architecture in Malta.

The photography is by Fabio Cunha, unless otherwise stated.

Project Loans:

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