Valley

A valley is defined as the internal angle formed where two sloping roof planes intersect, creating a channel that concentrates and directs water runoff toward the gutters. Valleys are one of the highest-volume water channels on a roof and are waterproofed with ice and water shield membrane covered by either metal valley flashing (open valley) or overlapping shingles (closed-cut or woven valley). Open valleys with W-shaped metal flashing provide superior long-term water management and are the preferred method for Owens Corning Platinum Preferred installations.