What can lead to improper drainage in roofing systems?

• A. Improper sump depth, blocked strainers, and freeze-thaw damage.
• B. Using too much slope reduces drainage requirements.
• C. Excessively large drains always prevent leaks.
• D. Improper sump depth, clogged scuppers, and UV degradation.

Answer: (A)

Improper drainage happens when water removal paths from the roof are not functioning properly due to limits in capacity, blockages, or damage. The best answer points to three real-world contributors: sump depth that is too shallow, which lets water accumulate and pond instead of draining; strainers or screens that become clogged with debris, reducing the flow area and causing backups; and freeze-thaw damage that can crack or distort drains and their connections, creating obstructions or misalignment that impede water movement. Together, these issues directly limit how quickly and reliably water can exit the roof, leading to ponding and potential leaks.

Other options don’t fit as well. Increasing slope generally improves drainage rather than reducing its requirements, though extreme slopes can bring other problems. Drains that are too large do not guarantee no leaks because blockages or improper installation can still prevent proper drainage. UV degradation can affect materials over time but isn’t a primary cause of drainage impairment like sump depth, blockages, or freeze-thaw damage.