Patent ID: 7413392

Claim:
A two-piece fastener assembly for securing two thermoplastic roof membranes to an underlying roof deck comprising: a) a metal stress plate of circular configuration defined by a top surface having an opening in its center portion for receiving a fastener therethrough; b) a thermoplastic coating covering and integral with the top surface of said metal stress plate; and c) a fastener positioned in said opening of said metal stress plate, wherein said metal stress plate comprises a first, second and third flat surface; d) a first circumferential portion, defined by a height forming a ridge or protuberance, extending above said second flat surface and towards said third flat surface at an angle of from about 25° to about 70°, connecting said second flat surface with said third flat surface; and e) a second circumferential portion, defined by a height forming a ridge or protuberance, extending above said first flat surface and towards said third flat surface at an angle of from about 25° to about 70°, connecting said first flat surface with said third flat surface; wherein the entire top surface of the metal surface plate, including the first, second and third flat surfaces, and the first and second circumferential portions, are covered by and integral with the thermoplastic coating.