Roof drainage is one of the fundamental considerations of building design. From the very dawn of building construction, it has been necessary to incorporate some method of gathering and discharging rainwater from the roof of a structure. In many cases, early structures were designed primarily as a shelter from the rain, their very purpose was to redirect rainfall and maintain a particular area as a dry habitat.
These structures were simplistic lean-tos, thatched huts and teepees, all of which served the same purpose. The design of these structures utilized a sloping roof, which naturally shed water without concern for collapse.