The National Roofing Contractors Association defines scupper as "A drainage device in the form of an outlet through a wall, parapet wall or raised roof edge typically lined with a sheet-metal sleeve." It is more often seen in apartments and other commercial buildings, though is sometimes found in residential homes constructed with flat roofs.
Roof scuppers are not the same as roof drains. Roof drains channel water through the deck of the roof into a piping system that carries water away, while a scupper allows water to drain through an opening in the side of the roof edge.
What Is a Roof Scupper?
A roof scupper is a drainage system for flat roofs that can't rely on sloping to naturally move water through a gutter system. Scuppers are essentially small devices that work by giving the water a mechanism through which it can escape the roof without passing through the interior of the building.
If a roof scupper becomes blocked or clogged and prevents water from draining from the roof surface, this could cause ponding or roof leaks. Cleaning and checking your roof drainage system is an important roof maintenance item.