The construction of the new Palace of Justice in Antwerp is the result of a policy of modernization of the judiciary institutionof the country. The legal services were particularly cramped in various buildings scattered across the city. In 1999, the Flemish Region decided to organise an international architectural competition for the construction of the new building.
The contract was awarded to the Richard Rogers Partnership team in association with Ove Arup and VK Studio offices who proposed an efficient, subtle and transparent building with a powerful symbolic image. The building has a floor area of 78000m² and meets stringent sustainability requirements through its orientation and maximum use of natural lighting and ventilation. The building, located on the Place Bolivar square, punctuates the end of the main boulevards of Antwerp on one side and has on the other a large green space interspersed with slip roads connecting to the motorways. One of these roads passes under the front of the building and leads onto the boulevard opposite front, thereby freeing up space for pedestrians and public transport. The fully glazed hall known as “la salle des pas perdus” (hall of lost steps) not only links to 6 wings but also creates an urban link between the park and the square, as a prolongation of the boulevard. Each wing comprises six floors, one of which is underground. The first three levels above ground are occupied by offices. The fourth is a technical level and the final floor regroups the various hearing halls, covered in roofs that resemble boat sails.
These “sail” roofs are the architectural focal point of the project.An extensive design study was necessary to determine the type of materials and construction methods required for these roofs. For example, wind tunnel studies were needed to determine the loads incurred during extreme weather. Each of the 32 roof modules is formed from four prefabricated quarters, that are then assembled on-site with a system of bolts. The geometric shape traced by these quarters is a hyperbolic paraboloid. This method simplifies the structural assembly and the fabrication of the components. Glued and laminated timber beams disposed on a frame in line with the straight lines of the sails and are mounted onto a tubular steel frame. Then three layers of planks are successively screwed on to form the shell.
The final roof covering is achieved with strips of 316L stainless-steel with Uginox Mat coating. Several technical constraints have pushed the designers towards this type of material: Natural durability, particularly when a site is exposed to maritime influences, the possibility of using welding techniques, complex geometry with either little or no angles in some places and extreme slants in others, lack of access for maintenance and of course; the visual aspect and colour.
To obtain a perfectly water-tight installation, the stainless-steel sheets are welded in a continuous seam using an automatic machine, thus creating an almost monolithic surface.
Text: SN - Constructalia