For open valleys, what is the minimum width of the top layer of valley lining required?

The minimum width of the top layer of valley lining required for open valleys is 36 inches. This width is critical because it ensures that adequate coverage is provided to effectively manage water flow in the valley, which is the area where two roof slopes meet. An insufficient width may lead to water runoff issues, potentially causing leaks or damage to the underlying materials and structure.

In roofing, open valleys are designed to allow for efficient drainage and help prevent debris accumulation, which could obstruct proper water flow. The broader valley lining minimizes the risk of water infiltration and increases the lifespan of the roofing materials by providing an additional protective layer. Proper installation according to these specifications is a key aspect of ensuring a long-lasting and watertight roofing system.