A head-of-wall joint for insulating the intersection between a wall assembly and the bottom of a floor or roof construction thereabove which utilizes an insulating gasket of a unique shape and construction positioned between the ceiling track and the point of intersection thereof with respect to the upper building floor or roof structure. The configuration of the insulating gasket member includes a main section and two side sections which extend over the outwardly facing surfaces of a conventionally configured ceiling track or runner without being attached to the ceiling track side panel side surfaces. The gasket can included tabs to attach to the lowermost edges of the track side sections. The gasket can be made from acoustically insulating materials or firestopping materials, or both.