In an insulating glazing unit including at least one curved rigid pane, another rigid pane and a spacer frame joining the two panes together by an impermeable adhesive, a space is created between the panes. The spacer frame has a variable cross-section over its length, looking in the direction of its longitudinal extension, in the region of the joining between the curved rigid pane and the other rigid pane. The spacer frame, in at least in the aforementioned region, includes a plastically deformed elastomer material when the two rigid panes are mutually pressed together.