What is the minimum dimension for scupper openings used for emergency overflow roof drainage?

The minimum dimension for scupper openings used for emergency overflow roof drainage is established to ensure adequate performance during significant rainfall events. Scuppers act as drainage points that help prevent water accumulation on the roof, which can lead to structural damage or leaks. A dimension of 4 inches is required because it provides sufficient capacity to handle excessive water flow while minimizing the risk of clogging or overflow during heavy rain.

This size is derived from building codes and best practices that balance practicality and safety. A dimension less than 4 inches may not effectively manage the water volume, especially in severe storms, leading to potential overload and damage. Therefore, the minimum of 4 inches serves as a reliable measurement to ensure that the drainage system is effective in protecting the integrity of the roof structure.