A type of warm roof in which all the layers, apart from the protective layer or practicable coating, are connected to the whole surface between them and the support. This system, renowned for its remarkable longevity, is “compact” because the insulation sections (generally with cellular glass) are attached to the support directly with hot bitumen.

Joints are also filled with bitumen and the waterproof bituminous membranes are then glued and fully bonded to the insulating layer. The compact roof is ideal for zones at risk or under great stress, for example public terraces, green roofs or parking roofs.