Roof drains are designed to carry water away from the roof and exterior of buildings. Roof drains come in a variety of sizes and shapes and can vary as to location and the size of the roof where they get installed.
A rain gutter, eavestrough, eaves-shoot, or surface water collection channel is a component of a water discharge system for a building. It is necessary to prevent water dripping or flowing off roofs in an uncontrolled manner for several reasons: to prevent it damaging the walls, drenching persons standing below or entering the building, and to direct the water to a suitable disposal site where it will not damage the foundations of the building. In the case of a flat roof, removing water is essential to prevent water ingress and prevent a build-up of excessive weight.
Water from a pitched roof flows down into a valley gutter, a parapet gutter, or an eaves gutter. An eaves gutter is also known as an eavestrough (especially in Canada), rhone (Scotland), eaves-shoot (Ireland) eaves channel, dripster, guttering, rain spouting, or simply as a gutter. The word gutter derives from Latin gutta (noun), meaning “a droplet”.