Roof drainage is an important consideration for commercial buildings with flat roofs. Even though technically, flat roofs have a few degrees of pitch, drainage must be facilitated to prevent water from pooling on the roof surface and creating problems that require roof repairs. There are a number of different methods roofers use to drain a flat roof, one of them being a roof scupper. In terms of promoting drainage and preventing the need for extensive roofing repairs, roofers have mixed opinions on the use of scuppers as opposed to roof drains.
What Is A Roof Scupper?
Roofing repair experts explain that a roof scupper is an architectural detail that is basically a cutout made into the curb of a flat roof to allow water to drain off the roof. Scuppers are usually used in conjunction with gutters and downspouts, which catch the water that flows through the scuppers and divert it elsewhere. Scuppers usually extend a few inches out from the edge of the building, and direct draining water into the gutter, or directly into a conductor head that leads into a downspout.
Common Concerns with Scuppers
There are two main concerns with roof scuppers that roof repair techs caution about. First, because scuppers are installed at the edge of a roof and drain directly to the outside of the building, they do not always prevent water buildup in the center areas of the roof. They are only efficient for use on roofs with enough angle to keep water moving toward the scupper for drainage. Flatter roofs may still experience standing water, unless roof drains are also installed.
Second, although most of the time scuppers drain the water flowing toward them, they are prone to blockage in a variety of ways. Scuppers are relatively small openings, so they are frequently blocked by debris that prevents water drainage. In colder climates, the ice and snow on a roof can also block scuppers and prevent drainage. When scuppers are blocked for any reason, and water cannot drain off a large, flat roof, the potential for damage requiring roofing repairs increases considerably.
What About Roof Drains?
Roof drains are installed in the surface of the roof so that water drains into a drain pipe that runs on the inside of the building to the storm sewers. Drains can be much more effective on roofs that do not include enough angle to keep water moving toward the scuppers. Still, just like scuppers, drains can also become blocked and cause water to pool on the roof. Roof drains can be a source of leakage that requires immediate roof repairs, since they are installed directly into the surface of the roof.
As simple as it may seem, drainage of flat commercial roofs presents its share of challenges. While scuppers may be sufficient for some buildings, roof drains may work better for others. They can also be used together for larger roofs to prevent water damage that could require roof repairs. Regardless of which method is used, some type of drainage system is essential to prevent water from collecting on a flat roof. Standing water on a flat roof almost always means a call to a roofing repair company to alleviate any blockages, and to develop a better means for keeping the rooftop drained!