Falls

Rainwater that remains standing on a flat roof after the rest of the surface has drained, typically caused by inadequate falls, structural deflection or blocked outlets. Persistent ponding adds load, accelerates deterioration of some coverings and can invalidate system guarantees.

Rigid insulation boards manufactured or cut to a wedge profile and laid to a designed scheme to create drainage falls on a flat roof, avoiding the need for screeds or firrings. Schemes combine tapered and flat boards to achieve both the required fall and the target U-value.

The drainage fitting through which water leaves a flat roof or gutter into the downpipe system, incorporating a clamped or welded connection to the waterproofing and usually a leaf guard or grating. Outlets are positioned at the low points of the falls, with secondary overflow provision to guard against blockage.

A channel that collects rainwater run-off from a roof and conveys it to outlets and downpipes. Gutters may be eaves-mounted, formed as valley or parapet gutters within the roof, or integrated into metal roofing systems, and are sized by rainfall calculation.