Which feature is vital for proper drainage in roofing systems?

Proper drainage in roofing systems is crucial to prevent water accumulation, which can lead to leaks, structural damage, and a reduced lifespan of the roofing materials. Gutter systems play an essential role in this process by collecting rainwater that runs off the roof and directing it away from the building's foundation, reducing the risk of water-related issues such as erosion, basement flooding, or damage to the landscape around the property.

While flat surfaces and inverted slopes can influence water movement, they do not actively manage water runoff in the same way that gutter systems do. Air vents are important for ventilation and preventing moisture buildup, but they do not serve a direct function in managing water drainage from the roof. Thus, gutter systems are the critical feature that actively facilitates proper drainage in roofing systems.