A flashing overlay system for overlaying roofing materials occupying a roof valley includes multiple planar flashing units having at least one first non-planar feature, the flashing units arranged in pairs including a left flashing unit and a right flashing unit, the flashing unit pairs covering the roofing materials occupying the roof valley along the length and track of the roof valley, the paired flashing units abutted together along the edges of the planar material supporting the at least one first non-planar feature, the first non-planar features aligned generally with the center line of the roof valley. The units are tired together with at least one elongated saddle strip folded over at longitudinal center and clamped over, fastened over, or otherwise fitted over the abutted first non-planar features of the multiple planar flashing units paired together and overlaying the roofing materials occupying the roof valley.