Abstract: A detail membrane for bonding together materials of a building envelope includes a reinforced inner core having first and second sides, a tacky, bitumen-based adhesive on the first and second sides of the reinforced inner core, rubber polymers and/or styrene-rubber block copolymers and/or other elastic materials added to the bitumen-based adhesive, wherein the detail membrane either bonds an underside of an exposed cover roofing material to an underlying roofing material on a building envelope, or bonds two like roofing materials together on a building envelope, or replaces caulking, plastic roof cement, mastic or any traditional material used on a sloped roof or the walls of a building exterior. The roofing structure can be roofing, flashing, protrusions through the roof, or walls that abut the roofing structure.