Abstract: An improved pressure sensitive flashing tape that is conformable over uneven or irregular surfaces for use in the construction industry, where a moisture and air seal having full adhesive contact to the adherend is required. The subject tape includes a topsheet layer and an adhesive underlayer. The topsheet is stabilized dimensionally as to tape length and width for ease in application, but is preconditioned with a plurality of diaphragm elements embossed into the topsheet and compacted under pressure so as to enable the tape to conform to raised and indented features, including lap joints, protruding screw heads, dents, holes, cracks and the like, in surfaces associated with flashing and associated building surfaces; thus improving weathertight sealing. The topsheet may also have fold lines disposed relative to the diaphragm elements so as to be complementary in function, the fold lines serving to further enhance conformability and adaptability during and after application.