Abstract: An aftermarket roof assembly for a vehicle comprises a frame which includes a trim ring having a passage opening and being adapted to be mounted in the roof opening in the roof skin from above. A main frame part carries longitudinal guide sections on either side of the roof opening, a drain channel assembly and drains act to drain off any water collected in the drain channel assembly. The main frame part is adapted to be mounted to the fixed roof from below. The roof assembly comprises first and second closure panels. The second panel is supported by the trim ring and is positioned behind the first element when the elements are in their closed position. The first panel is moveable by means of the longitudinal guide sections at least between a closed position closing the passage opening and an open position in which it is slid under the second panel and opens the passage opening. Screen assemblies are provided to cover the panels from the interior of the vehicle.