Few features are as important to roof performance as proper slope and drainage. Water standing on a roof increases the chance of leaks and water infiltration significantly. Making sure you have good drainage is a very important reason for regular roof inspections. Leaves, trash, debris, and other objects can clog or obstruct roof drains, creating standing water. Regular cleaning of roofs can help remove such problems and allow water to drain properly, which reduces the chance of leaks. Also, water is heavy – weighing about 5 pounds per square foot per inch deep.
Poor drainage also causes deterioration of roofing materials, leading to a shorter life of the entire roof system. If a leak occurs from standing water, insulation can get saturated over a wide area, which could require entire roof replacement.