Why is valley flashing considered a vulnerable area?

Valley flashing is considered a vulnerable area because it carries a large volume of water as it collects runoff from both sides of a roof valley. When it rains, this area is subjected to significant water flow, which can increase the potential for leaks and damage if not properly installed or maintained. The concentration of water in these areas makes them critical points for waterproofing in roofing systems, and if the flashing is defective or improperly sealed, it can ultimately lead to water infiltration into the building.

While UV exposure, maintenance neglect, and access issues can also pose challenges to other areas of a roofing system, the primary reason valley flashing is classified as vulnerable stems from its crucial role in managing the high volume of water, emphasizing the need for careful installation and regular inspections.