A fastener assembly including an internally threaded nut and an externally threaded screw for securing at least two materials together. A combined thickness TM of the materials is less than a length SL of the screw inserted into the materials. The nut includes a head, a shank extending from the head, and an internally threaded bore extending into the shank. The screw includes a head and an externally threaded shank adapted to threadingly engage the internally threaded bore of the nut. An encapsulating plastic layer covers the head of the nut. The plastic layer extends under and covers a bottom surface of the head. The plastic layer has a thickness TE below the bottom surface of the head which is equal to or greater than a difference between the screw length SL and the material thickness TM.