The present superstructure involves, for each upright, a spacer section bar (3), a hinge-bearing section bar (6), a hinge (8), a piston (13) that helps to lift the pane (1), and is completed by a gripper (9) for supporting the pane (1), a closing section bar (11) and a gasket; the section bar (3) has a box section so that it can be adjusted to be joined together with the section bar (6); each hinge (8) is fixed to the section bar (6) and at its end to be fixed to the gripper (9), bears conical guides (8.1) suitable for fitting the conical arms (9.1) situated on the gripper (9) itself; a gasket (12) is fixed to the gripper (9); where spherical panes (1) are involved, hinges (15) are used containing a body (15.1) and a connecting piece (15.2) that can be rotated with respects to the body (15.1) so that the panes (1) can be fitted on at different lengths of the circular arc.