Abstract: The invention relates to a sub-ceiling with a supporting framework in the form of a grid of insecting bearing rails (1), which is able to be suspended at points of intersection of the bearing rails (1), formed by the nodal elements (2), and the open regions (34) of which are able to be secured in an air-tight and dust-tight manner on the peripheral edges by insert members which may take the form of coffers, lighting elements, air-supply devices or air-outlet devices. The insert members rest in a sealing manner on a sealing means on the bearing rails (1), whereby in order to simplify manufacture, construction and assembly and to fulfill the requirements of clean-room conditions, the bearing rails (1) are attachable in an air-tight and dust-tight manner to the nodal elements (2), with the bearing rails (1) having angular supporting flanges (3) on their end walls (15) and the respective nodal element (2) has bearing surfaces (18) cooperating with the supporting flanges (3) to support the bearing rails (1).