Foldable accommodation unit to be mounted on the roof of a motor vehicle

The module has a fixed lower tray (4) supporting a tread cushion and a movable upper tray (5) articulated around lateral hinges. The movable tray is half opened by a spring (12) up to an angle greater than a preset value in a deployed phase and opened manually up to an angle greater than another preset value in another phase. Ends of the spring are articulated on the tray (5) and on an arm (16) articulated close to the hinges.