In terms of its construction, the roof pursues the idea of preservation because it is totally separate from the existing building, floats, as it were, above the essentially unchanged courtyard façades. The loads are carried via modern steel structures, their delicate, branching form reminiscent of trees. Large sound absorbers fitted between the “branches” ensure good room acoustics. The triple-glazing units chosen for the upper, i.e. outer, glazing guarantee optimum thermal performance in winter. Below the load-bearing structure, laylights form a second layer of glazing. Glass in various colours here plus movable louvres to control the incoming light will determine the lighting in the chamber.
Four mock-ups have been built to assist the design work. The largest of these measuring 7.5m x 12m and replicating a complete corner of the roof including drainage and the junction with the building. This mock-up is subjected to the thermal cycling test, which is compulsory in North America and verifies the imperviousness of the design even under extreme temperature and pressure fluctuations.
Images: © ARCOP/FGMDA