With a proper roof drainage system, you won’t have these problems. A great system protects your property in two ways.
The primary role is to allow complete draining of your roof. Pooling can be detrimental, especially to low-sloping roofs. If allowed to pool on the roof, water will soon find enter the building envelope and wreak havoc.
The secondary role is steering water clear from the foundation. If water continually drains from a roof and constantly collects under the eaves, it could lead to problems like: leaky basements, damage to basement walls, soil erosion; and ultimately the deterioration of your foundation.