How should valley flashings be designed at the bottom?

Valley flashings play a crucial role in directing water flow away from vulnerable areas of the roof, particularly where two slopes meet. The design of valley flashings at the bottom focuses on managing water effectively rather than allowing for its accumulation. Properly designed valley flashings are intended to channel water to the gutters and prevent it from pooling, which can lead to leaks or other water-related issues.

Emphasizing the characteristic of preventing water passage reinforces the core function of valley flashings. This means the bottom design must include a slight slope or channeling effect, ensuring that any water that does accumulate flows away from the roof surface and into appropriate drainage systems. Enhancements that aid in directing water, such as raised edges or integrated features that mitigate water flow, further assist in maintaining the integrity of the roofing system.

The focus on avoiding water accumulation at the bottom level ensures that the roof remains watertight and minimizes the risk of serious damage over time due to trapped water.