Dominique Coulon carves rock-like volumes from monolithic concrete on the cliffs above a Basque fishing port
St Jean de Luz is an elegant fishing port in south-west France surrounded by rocky promontories. Now Strasbourg-based architect Dominique Coulon et Associes has added a manmade version. The St Jean de Luz Cultural Centre is a dramatic sequence of in-situ concrete volumes that collide and spill into a central three-storey atrium like a major tectonic event. Deep-set windows frame ocean views, and the sparkling Atlantic light washes in from openings on all sides. “We wanted to create a monolithic building with no visible joints or formwork holes, and with a surface that was as smooth and soft as possible,” says Coulon. “We like concrete because – unlike wood and metal – it can be continuous and does not reveal how it was assembled, much like rocks and mountains.”
The building programme is arranged on either side of the atrium: to the east, a 900m2 theatre; to the west, a music school, theatre rooms and dance studios. These facilities project into the atrium in a series of steps and overhangs, with the main stairwell scissoring 4.2m over the entrance area. Most spaces are column-free, with long spans supported on 300mm-thick slabs.
To achieve this cantilevering structure, temporary formwork had to remain in place throughout construction. “It was only once the building was completed that the shoring could be gradually removed, as the structure of the cultural centre is like a kind of envelope that only holds together when it is finished.” The formwork had to be removed very carefully and in a precise order, to account for the deflection of the concrete.
Steel formwork was used throughout, and the finish was left as-struck, apart from the tops of the balustrades, which have been polished. Board layouts were worked out in close collaboration between the architect and contractor. “We positioned the joints according to the layout of the spaces, but the idea was not to impose an overly rigid and restrictive plan, rather to work with the contractors' tools, following the logic we had chosen.” Coulon adds that cement replacements were used to reduce the embodied carbon of the structure.
This is a building that has been designed to last, with longevity intrinsic to its sustainability credentials. “These open spaces can evolve with changing uses without requiring any work,” says Coulon. However they are used, at the heart of the St Jean de Luz Cultural Centre will always be the shimmering play of light on concrete. “Concrete’s surfaces are never truly uniform, and the cloud-like shapes that develop on them create very sensitive interiors. As a material, it has great poetic potential.”