What does ponding refer to on a roof?

• A. Water remaining on the roof surface due to poor drainage.
• B. A type of interior leak.
• C. A weather event.
• D. A drainage feature that vents water to the atmosphere.

Answer: (A)

Ponding refers to water that remains on a roof surface after rain because drainage is insufficient or low spots collect water. This standing water is a condition, not a leak by itself, but it signals drainage design or maintenance problems.

Why this is the best description: it captures the practical issue roofing systems face on flat or low-slope roofs—water that doesn’t drain away. Standing water adds dead load, can freeze and cause damage through freeze–thaw cycles, and accelerates membrane deterioration, potentially leading to leaks over time. The other options describe interior leaks, weather events, or drainage features that vent water, which are not what ponding means.