An exterior roll-up shutter consists of positioning strips that can be mounted on an outside wall on or next to the reveals and of a housing that rests against the strips. The housing is constituted of side walls, a floor, a rear and front wall, and a ceiling. The housing accommodates the shaft and panels of the shutter itself. It has a shutter exit extending along its floor in alignment with guide channels in the positioning strips. The shutter also consists of the paneled shutter itself, which is accommodated in the housing. To facilitate both installation of an exterior roll-up shutter of the same overall type and replacement of the paneled shutter itself, each positioning strip, which consists of a length of section with a shutter offset that is accessible from inside the window aperture, has an accommodation that extends along the whole strip. The accommodation is accessible from the weather side. An auxiliary assembly structure associated with one of the side walls of the housing permanently extends into it at a right angle to the strip. It can be used to lift the housing over the positioning strip until the shutter exit in the floor of the housing is in alignment with the guide channels in the positioning strips, while allowing the housing to be freely maneuvered at its installation level at the window.