Rainwater funnels with a filter for leaves are used to remove rainwater from the surface of flat roofs. Additional fixing to the base is needed for proper installation. The horizontal part of the installed funnel is welded up between two layers of bitumen-polymer materials of the roofing.
The models with heating which prevents the drainage hole from freezing in the offseason time (autumn – winter - spring) are also available.
The number of funnels needed for each roof depends on the architecture, roofing conditions, and the value of precipitation in the region. At an average, one funnel installed in every 200 - 300 m² is enough. The minimum amount is 1 funnel for one roof.