Case Studies: Plan-les-Ouates

1-2024: Stone

Architecture: Gilles Perraudin and Atelier Archiplein
Engineering: Marty Construction
Area: 12 500 m²
Function: 4 social housing units with 68 apartments
Built: 2017–2021
Location: Plan-les-Ouates, Switzerland
Materials: Migné and Chauvigny limestone
Cost: € 25 000 000
Client: Plan-les-Ouates’i municipality

One of the aims of the project was to demonstrate the possibility of building with massive-precut stone in Switzerland, i.e., the economic viability, structural capacity and construction-technological opportunities of the material. The load-bearing structure of the buildings consists solely of massive stone, three consecutive layers of which (façade, interior walls of apartments and circulation spaces) hold up the whole building. Thanks to this, there is no need for additional concrete, GLT or steel structure.

The form of the buildings is simple and orderly. The façade is ‘ornamented’ with technical elements such as the rainwater-diverting cornice, which also establishes a clear horizontal rhythm in the façade, and regular stonework with visible joints. Unpolished stone walls, made of 190 × 80 cm blocks, exhibit cutting marks as well as the natural irregular look and composition of the stone that has developed over hundreds of millions of years. The load-bearing stone structure was left unfinished in the façade, apartments as well as common areas. Massive-precut stone in the walls functions also effectively as thermal mass, helping to cool down room temperatures during hot weather.

Designing large-block stonework also revealed some shortcomings—limited production capacities of the quarry and natural cracks in the limestone were not foreseen in the drawings of architects. This once again underlines that when designing with natural materials, it is necessary to first get acquainted with the quarry and its possibilities, and only then infer the dimensions of pieces and the possible stonework or structure. Architectural studio Archiplein emphasises that besides its environmental friendliness, one of the most important aspects of building with natural materials is the challenge it presents to the current model of construction and production by providing good examples of alternatives.