Roof Valleys: Roof valleys are the points where sloped sections of roof meet, usually at an angle. The valleys direct water into the gutters to remove it from your roof. Valleys may be made of materials such as metal flashing, interlaced shingles or rolled roofing. The repair technique you use will depend on what kind of material forms the valleys and the manner in which the valleys are constructed. In open valley construction, shingles do not cover the valley, which has flashing or rolled roofing material as the base. In closed valley construction, interlaced shingles form the valley. Valleys are weak spots in a roof, prone to leaks that may worsen during heavy rainfall because of the way the shingles are applied over and around the area.