What is the minimal allowable size of slope for perfect drainage at the roof?

The minimal allowable size of slope for effective drainage at the roof is ¼ inch per foot. This slope is critical because it ensures that water is directed towards the roof drainage system, preventing pooling and potential water damage. A slope of ¼ inch per foot corresponds to an overall incline that facilitates proper runoff. It is widely accepted in roofing standards as sufficient to ensure that water flows off the roof efficiently during rain events, minimizing the risk of leaks and structural issues.

A slope of less than ¼ inch per foot may result in stagnant water, which can lead to deterioration of roofing materials and increased maintenance issues. Therefore, configuring roofs with this minimal slope is essential for longevity and effectiveness in drainage.