Abstract: The invention relates to an improved flashing system and method for controlling water and air intrusion around windows, doors, louvers and other wall penetrations. More specifically, the invention utilizes commercially available products such as coated polyethylene sheet material and elastomeric rubber adhesive sealant in a unique manner. It has been found that this polyethylene coated material can be creased and folded to form a flashing component and serve to control water and air intrusion. Prior to this invention, a separate pre-molded termination accessory was required to effectively seal corner areas around window and door rough openings. Additionally, the invention provides for full perimeter flashing and supplemental sealing at selected joint locations prior to installation of a closure member in the opening to prevent water and air intrusion around windows, doors and other building openings.