In a roof window with a frame structure and an openable, pane supporting sash structure, the top, bottom and side members (1-8) of the frame and sash structures are for the major part made as wood profiles, which on the outwards facing sides are covered by covering members of weather-shielding material connected with the wood profiles by means of engagement and securing means. The covering members (11, 12, 15, 17, 20, 21, 32) consist of an upper and a lower cap member (20, 21) on the frame and sash side members (3, 4, 7, 8) designed as flat, trough-shaped profiles with identical, substantially U-shaped profile cross section comprising an exterior wall (20a, 21a) and two low side walls (20b-c, 21b-c). The lower cap member (21) has at its upper end a joggled connection member (22) inserted under the lower end of the upper cap member (20), said connection member having such a shape that the cap members (20, 21) in the closed position of the window are placed with their exterior walls (20a, 21a) and side walls (20b-c, 21b-c) in alignment with each other, and that the lower cap member (21) when the window is opened may swing unimpededly outwards relative to the upper cap member (20).