Abstract: A ventilation assembly, such as for ventilating the interior of a motor vehicle body, comprises a frame moulded from rigid thermoplastics material defining side walls, end walls and a dividing wall which form apertures controlled by flap valves. The flap valves can be moulded in situ from flexible material but which is not compatible with the rigid material of the frame and therefore does not adhere to it during the moulding process. The material of the flap valves is provided with a series of holes through which protrude studs having enlarged heads to form hinges to enable the flap valves to flex between open and closed positions. In the closed position, the flap valves seal against seats. Other embodiments are shown in which the flap valves can be moulded of rigid material with hinge formations arranged to hingeably interlock with corresponding formations on the frame.