Butterfly roof

A butterfly roof is a form of roof characterized by an inversion of a standard roof form, with two roof surfaces sloping down from opposing edges to a valley near the middle of the roof. It nomenclature is derived from its form being shaped like a butterfly's wings. Butterfly roofs are associated with mid-century modern architecture. The form has no gutter as rainwater can run off the roof in no more than two locations - at either end of the valley, often into a scupper or downspout. The form may be symmetrical, with the valley located in the center, or asymmetrical with an off-center valley. The valley itself may be flat, with a central roof cricket diverting water towards the valley ends, or sloping if the entire roof form is tilted towards one end of the valley. The roof also allows for higher perimeter walls with clerestory windows allowing light penetration without impacting privacy.