Double-level drainage system for flat roofs

摘要

A draining system for water which may collect between the upper and lower membranes of flat, horizontal or slightly sloped insulated roofs upon perforation of the upper membrane. The insulating panels located between the two membranes are provided at both their upper and lower faces with a network of intersecting grooves, and these networks communicate with each other through passages made through the insulating panels or constituted at the panel joints. A lower drain member is sealed to and opens above the lower membrane to drain any water having seeped under the broken or perforated upper membrane, so as to prevent deterioration of the insulating panels and water accumulation which may provoke considerable roof overload problems. In certain roof constructions, the network of upper grooves is not necessary.