What defines open valleys in roofing?

Open valleys in roofing are characterized by roof plane coverings that do not overlap each other across the valley center. This means that instead of utilizing a method where roofing materials are layered over one another, the open valley approach allows for a clear, visible channel where the valley's flashing and structural materials can be seen.

This style not only serves an aesthetic purpose but also enhances drainage, as water flows directly into the valley without interruption from overlapping materials. The absence of overlapping materials also helps prevent water from being trapped, thereby reducing the potential for leaks and other water-related issues.

In contrast, other methods such as interwoven shingles or complete overlaps can lead to potential obstructions in water flow and may not be as effective at managing runoff. The visibility of flashings is more about the installation technique rather than the definition of an open valley itself.