Final answer:
Ponding water is the most common cause of leaks in flat roofs, as it often occurs when water accumulates and does not drain properly, leading to roof damage over time.
Step-by-step explanation:
The question concerns the most common cause of leaking in flat roofs. There are several potential causes of leaks in flat roofs, including issues with seams, ponding water, parapet walls, and gutters. Each of these has unique characteristics that can contribute to a leak, but some are more commonly at fault than others.
Seams can be a significant source of leakage if they are not properly sealed. During the installation process, the seams of the roofing material are bonded together to create a continuous barrier against water. If the bonding process is not done correctly, or if the sealant degrades over time, water can seep through these weak points.
Ponding water is another frequent issue with flat roofs. Ponding occurs when water accumulates on the roof and does not drain properly. The water's weight can cause the roof to sag, exacerbating the problem and increasing the risks of leaks.
Parapet walls, which are the small walls constructed around the perimeter of some flat roofs, can also cause leaks. These walls are intended to protect the edge of the roof but if they are not correctly waterproofed, they can allow water to enter behind them, leading to leaks inside the building.
Gutters are designed to channel water away from the roof. If they are blocked or not installed correctly, water can back up and potentially cause leaks.
While each of these concerns could lead to leaks, the most common cause of leaks in flat roofs is traditionally ponding water. This is due to the fact that flat roofs do not drain as effectively as pitched roofs, and without proper drainage systems in place, water tends to collect and cause damage over time.
The correct answer to the question is that b. Ponding is the most common cause of leaking in flat roofs.