Solar waterproofing for the Marseille FRAC

The city planning rules and the particular geometry of the land (which includes 3 plots) were decisive criteria from an architectural point of view. To fulfil the specifications, the roof was considered from the outset not as a roof as such, but rather as an extension of the façade. The major challenge was therefore to ensure continuity of the shell, except on the side from the street, and therefore to use the same cladding.

The double-skin façade is made up of 1500 untinted glass elements, in variations of white of different opacity and installed at a variable distance from the watertight façade. This organization creates an animated façade with elements reacting to climatic variations. The entire structure offers lightness, transparency and openness to the slender and pixelated shell, changing and alive...

What solution should be used to ensure the façade-roof continuity sought for this HQE building?

Yet another big challenge appeared: Marseille was designated in 2008 as the “European Capital of Culture” for 2013. It would be a major event, bringing together more than 900 artistic and cultural events. It was therefore imperative to deliver this project on time so that the Marseille FRAC would be there for this unique event which was key for the outreach of the city.

Six months of research and testing on prototypes made it possible to develop the perfectly adapted solution along with SNA. 

A specific framework device based on the BMI-Siplast T-Fix process was implemented. This technical solution responds to a double need:

• provide a frame that supports the fibre cement cladding

• integrate this frame into the waterproofing without altering its reliability, therefore without drilling it or exerting too much pressure on it.

The T-Fix process had already proven itself on photovoltaic flat roofs and the Study of New Techniques was decisive for the validation of the supervising office. 

In terms of the waterproofing itself, we implemented a classic two-layer coating by mechanical fixing on the concrete support. The polyester profiles reinforced with fibreglass were bonded to the support through the waterproofing membrane. The strips of the second bituminous layer cover the flat part of the rail, on which the cladding supports (spacers) are fastened, which are arranged randomly, but according to a very precise layout. The building also hosts more traditional roof terraces: 3 wooden terraces and a non-accessible green roof terrace.