Corner flashing system

A method of forming a flashing member, the method comprising the steps of:

• cutting an appropriately sized, substantially rectangular flat sheet of flashing material, having a bottom edge, a top edge and two side edges, from a center of its bottom edge to a terminus a distance “d” from the bottom edge, thus forming two cut edges that each define an edge of a first flap and a second flap;
• creasing the sheet along a line that begins at the terminus and extends in the direction of the cut to the top edge of the sheet;
• creasing the sheet along a line that is perpendicular to the direction of the cut, intersects the terminus of the cut, and stretches from one side edge to the other side edge;
• and
• separating the cut edges while folding the sheet along the creases in a manner such that the first and second flaps remain in the plane of the former flat sheet, thereby adapting the flaps to engage a vertical wall, the cut edges define a ninety-degree angle in the same plane, and the remainder of the former flat sheet defines an “L”-shaped seating flange extending into the plane of the former flat sheet, wherein the seating flange is adapted to fit in a corner of a window frame.