It is a system used to build non-treadable metal flat roofs for industrial buildings. These roofs have a gradient ranging between 1% and 5%. It is type of hot roof, since the thermal insulation is to be laid under the waterproof membrane. 
Laying: the vapor barrier is applied on the metal plates forming the roof. The POLIISO^® ED expanded polyurethane insulation panels are applied on this surface by trying to perfectly fit each panel together to cover the entire roof. The panels are to be fastened mechanically using screws at about 10 cm away from the perimeter of the insulation panel: do not insert them either along the edges or at the center of the panels. The screws must be long enough to cross the thermal insulation and the metal plate. The waterproofing membrane is then applied on the insulation layer and it too is to be fastened mechanically along the perimeter. In order to overlap two strips of adjacent membranes, use adhesive or hot air, depending on the type of bituminous membrane and on the manufacturer's instructions. The roof is then finished with a heavy protective layer.