Roofs are used more and more comprehensively. Almost anything that can be done on the ground can now be done on roofs and decks too, as long as the correct technology is used. For example, long-lasting and functional walking paths and driveways on decks and roofs require a well-designed system. These ensure the continuity of the roof functions (e.g. continuous water retention and drainage capacity) and make it possible to withstand the lateral forces generated by accelerating, braking, and steering.
Unlike with rainwater retention or delaying done on green roofs, water must be removed almost entirely from the surfaces of walkways and driveways and from beneath the surfaces. The flow factor of water in tiled areas varies from C = 0.8 to 1.0; drainage must be designed in a way that makes it possible to drain on two levels: the levels of the drainage and the surface area.