Since a valley is designed to channel water between two pitch areas a valley receives more water flow than any other part of the roof. A standard installation guideline on all roof systems is to never install fasteners in the valley’s center. Exposed valley fasteners disrupt the immediate flow of water. Because valleys are transition areas and absorb building movement, fasteners installed in the valley center uplift and allow water seepage. The only way to properly repair this issue is by replacing the valley flashing.