When are roof drains required?

Roof drains play a critical role in managing water that accumulates on a roof, particularly in preventing structural damage and ensuring safety. The correct context for requiring roof drains is in situations involving parapet walls. Parapet walls can trap water when it collects on a flat roof, leading to potential issues such as leaks and added weight from accumulated snow and water. Roof drains are necessary to provide an outlet for this water, ensuring that it is redirected away from the building, thus maintaining the integrity of the structure.

Other scenarios, such as flat roofs or heavy snowfall, do not by themselves guarantee the need for roof drains without the context of potential water accumulation and lack of drainage solutions. While it is likely that many flat roofs will need drains, the presence of a parapet wall specifically heightens the risk of water retention, making drains essential. Consequently, not every flat roof or commercial building will require roof drains unless they also feature conditions such as parapet walls.