Insulating glazing unit, at least comprising a first pane, a second pane and a third pane and a circumferential spacer, the spacer at least comprising - a polymeric main body comprising a first pane contact surface (2.1) and a second pane contact surface (2.2) running parallel thereto, a first glazing interior surface (3.1), a second glazing interior surface (3.2), an outer surface, a first hollow chamber (5.1), and a second hollow chamber (5.2), wherein - a groove to accommodate a pane runs parallel to the first pane contact surface (2.1) and the second pane contact surface (2.2) between the first glazing interior surface (3.1) and the second glazing interior surface (3.2), - the first hollow chamber (5.1) is adjacent the first glazing interior surface (3.1), and the second hollow chamber (5.2) is adjacent the second glazing interior surface (3.2), - the lateral flanks of the groove are formed by the walls of the first hollow chamber (5.1) and of the second hollow chamber (5.2), - the outer surface is divided into a first outer surface (4.1), a second outer surface (4.2), and a bearing edge, - the bearing edge runs substantially perpendicular to the pane contact surfaces and connects the first outer surface (4.1) and the second outer surface (4.2) to one another, - the first outer surface (4.1) and the second outer surface (4.2) enclose in each case an angle α (alpha) of 100° < α < 160° with the bearing edge, wherein - the first pane is bonded via a seal to the first pane contact surface (2.1), - the second pane is bonded via a seal to the second pane contact surface (2.2), - the third pane is inserted into the groove of the spacer, - the edge of the first pane, the edge of the second pane, and the bearing edge are arranged flush, wherein the first pane and the first outer surface (4.1) delimit a first outer interpane space (24.1) and the second pane and the second outer surface (4.2) delimit a second outer interpane space (24.2), and - the outer interpane spaces (24.1, 24.2) are at least partially filled with an outer seal that is adjacent the seal. - a polymeric main body comprising a first pane contact surface (2.1) and a second pane contact surface (2.2) running parallel thereto, a first glazing interior surface (3.1), a second glazing interior surface (3.2), an outer surface, a first hollow chamber (5.1), and a second hollow chamber (5.2), wherein - a groove to accommodate a pane runs parallel to the first pane contact surface (2.1) and the second pane contact surface (2.2) between the first glazing interior surface (3.1) and the second glazing interior surface (3.2), - the first hollow chamber (5.1) is adjacent the first glazing interior surface (3.1), and the second hollow chamber (5.2) is adjacent the second glazing interior surface (3.2), - the lateral flanks of the groove are formed by the walls of the first hollow chamber (5.1) and of the second hollow chamber (5.2), - the outer surface is divided into a first outer surface (4.1), a second outer surface (4.2), and a bearing edge, - the bearing edge runs substantially perpendicular to the pane contact surfaces and connects the first outer surface (4.1) and the second outer surface (4.2) to one another, - the first outer surface (4.1) and the second outer surface (4.2) enclose in each case an angle α (alpha) of 100° < α < 160° with the bearing edge, wherein - the first pane is bonded via a seal to the first pane contact surface (2.1), - the second pane is bonded via a seal to the second pane contact surface (2.2), - the third pane is inserted into the groove of the spacer, - the edge of the first pane, the edge of the second pane, and the bearing edge are arranged flush, wherein the first pane and the first outer surface (4.1) delimit a first outer interpane space (24.1) and the second pane and the second outer surface (4.2) delimit a second outer interpane space (24.2), and - the outer interpane spaces (24.1, 24.2) are at least partially filled with an outer seal that is adjacent the seal.