Law Courts in Nanterre, France

Integrated into the topography of the site, the building extends over seven storeys, three of which are underground and accommodate parking spaces, archives and mechanical services. The overall floor area is 21,300 m2. The structure is enclosed by a transparent bubble-like glass skin, within which the individual storeys seem to float in space.The load-bearing concrete structure allows an extremely flexible layout. Specially prefabricated modular formwork elements were used to construct the the waffle slab floors. For the first time, compressed air was used on site to remove the shuttering – a technique that is normally employed only for precast concrete elements or in tunnel construction. To ensure that the arrises were as sharp as possible, the formwork was removed extremely slowly. The hydraulic jacks were lowered by only about 4 cm after the concrete had set, so that the compressed air could separate the steel formwork slowly from the concrete and prevent it adhering too strongly. To maintain the impression of a constant floor thickness with a regular waffle grid, the slab was increased in depth within the cells at those points where a beam would normally have been necessary to bear additional loads. The execution of the structural work had to be extremely precise, since a maximum tolerance of 5 mm was necessary to ensure an exact fitting of the prefabricated finishing elements.