Drainage reliability describes preventing what response to water load?

• A. It prevents ponding and potential structural collapse from water load.
• B. It prevents corrosion of metal components.
• C. It prevents heat gain.
• D. It prevents UV degradation.

Answer: (A)

Drainage reliability is about ensuring water is shed so it doesn’t pond on a roof. When water collects, it adds extra load on the roof structure. That ponding load can cause deflection, damage to the membrane, and, in extreme cases, compromise the structural integrity or even lead to collapse. So the primary concern is preventing ponding and the resulting response from the water load. The other options describe issues related to moisture exposure that aren’t the direct consequence of water accumulating and stressing the roof structure.