A multi-piece frame (5) for an open roof assembly is manufactured by providing a first frame element (20) having an edge and a first attachment area (21) adjacent to the edge; providing a second frame element (30) having a second attachment area (31); arranging the first attachment area and the second attachment area at least partly over each other; applying a fluid sealant (43) adjacent to the edge of the first frame element; applying a sealing element (40) on at least one of the first frame element and the second frame element and on the sealant, while the sealant is still at least partly fluid; and curing the sealant to provide a fluid-tight sealing between the first frame element, the second frame element and the sealing element. Thus, fluid tight connection between the sealing element and the sealant is provided in a reliable manner.