What is the minimum size horizontal pipe required for a flat roof measuring 180 x 100 feet with 5 equally spaced roof drains?

To determine the minimum size of a horizontal pipe required for a flat roof with specific dimensions and a certain number of roof drains, it's essential to consider the total drainage capacity necessary for the entire area. A flat roof measuring 180 x 100 feet has a significant square footage of 18,000 square feet.

For effective drainage, local plumbing codes provide guidelines for the sizing of horizontal pipes that consider factors such as the roof area and the number of roof drains. Typically, the calculation involves assessing the area served by each drain and ensuring that the pipe can handle potential water flow during heavy rainfall events. Each drain will support a section of the roof, and with five equally spaced drains, we can distribute the drainage load among them.

Based on the standard guidelines, a pipe size of 5 inches allows for sufficient capacity to handle the expected runoff from a roof of this size, even under significant precipitation conditions. It ensures that water can be drained quickly and effectively, preventing issues such as pooling or flooding on the roof. Thus, selecting a pipe diameter that adequately accommodates the planned drainage design is crucial in maintaining the integrity and functionality of the flat roofing system.