Speaking the language of a roofing contractor can be a difficult skill to master. Most professions develop a unique vernacular over time that allows members of the profession to speak about details and projects with ease. However, it can appear to those on the outside of the profession that a tradesperson is speaking in code.
This is the case when a homeowner or building owner hears a contractor talking about a scupper versus a roof drain. Both are used to provide drainage for a roof system. However, they are not interchangeable. The term needs to be clarified when identifying the specific detail that you may have on your roof system because the corrective action for addressing these details and providing repairs is different.
In short, a scupper is a detail that provides drainage to a roof system by allowing the water runoff from the roof to exit the roof through a metal edge, parapet wall or through the deck into a downspout or leader not run through the interior of the building.
In contrast, a roof drain is a method of draining a roof assembly where the water runoff from the roof is transferred through the roof drain into piping that runs through the interior of the building before it empties either onto grade or into a storm sewer. In most cases, roof drains are also installed in such a way that prevents water from leaking out of the drain in the event that there is a clog somewhere in the drain line.
Scupper drains do not normally provide protection against water back up and, as a result, they are not recommended to provide drainage when they cannot be drained to the outside of the building. In addition, scuppers can be prone to freezing during winter weather conditions since their drain lines are external to the building and do not remain exposed to the heated interior of the building.
Have you experienced problems with scuppers or roof drains freezing during cold weather conditions? What solutions have you implemented to help relieve these conditions?
Photo © Jurin Roofing Services, Inc. Roof drain.
Photo © Jurin Roofing Services, Inc. Roof scupper system.