An open valley is a type of roof valley that does not have any metal flashing covering the seam between two sloping roof planes. Instead, an open valley uses shingles or other roofing materials to create a visible seam that runs along the valley of the roof.
The primary advantage of an open valley is its aesthetic appeal. The use of shingles or other roofing materials to create the valley seam can create a more natural and seamless appearance, blending the valley seamlessly into the overall roof design. This can be particularly beneficial for roofs with complex or irregular shapes.
However, open valleys are generally less durable than closed valleys, which use metal flashing to create a watertight seal at the valley seam. Because open valleys rely solely on shingles or other roofing materials to protect against water infiltration, they may be more susceptible to leaks and other damage over time.
The decision to use an open valley or a closed valley in roofing construction will depend on a range of factors, including the design of the roof, the climate in the area, and the overall aesthetic goals of the project. Proper installation and maintenance of either type of valley is critical to ensuring the long-term durability and performance of the roof.