This deck raised various issues, the wrong overall building of the slopes provoked waterloggings in most of the surface deck which came along with a lot of leakings as the former waterproofing was failing and both expansion and permitral joints were failing as well. In addition, the existance of 139 skylights at ground level made it very dangerous for manteinance personnel to walk about the deck. First thing to do was raising the skylight from ground level to 1,70 metres so they were not a threat anymore. Secondly, to resolve the waterlogging problem, we recalculate and remade the slopes with aerated concrete and a compression layer made with R4 ressistance mortar in which we finally sprayed our Sikaroof Pro+ system based on polyurethane lining. We finished the job with a white UV protective poliurethane layer.