A method of manufacturing a roof window comprising a frame, a sash, and a pane, in which the frame comprises a set of frame members including a top frame member, two side frame members (22, 23) and a bottom frame member and the sash comprises a set of sash members including a top sash member, two side sash members (32, 33) and a bottom sash member, each frame and sash member defining a longitudinal direction, and the pane comprises a number of edge portions and an exterior pane surface defining a plane of the roof window in an assembled condition of the roof window, each sash member (31, 32, 33, 34) comprising a profile element (31a, 32a, 33a, 34a), an inner element (31c, 32c, 33c, 34c) and an intermediate element (31b, 32b, 33b, 34b) forming a connection between the profile element and the inner element of each sash member in an assembled condition of the sash, the profile elements (31a, 32a, 33a, 34a) of the sash members (31, 32, 33, 34) being located along respective exterior edge portions of the pane in the assembled condition of the sash, and the profile elements (31a, 32a, 33a) of the top sash member and the two side sash members (32, 33) being formed as a set of longitudinal profiles of substantially uniform cross-section, comprising the steps of: providing a set of three longitudinal profiles, optionally from a single profile length, forming mitre shapes at mutually facing ends of the longitudinal profiles, optionally such that the three longitudinal profiles are coherent, providing a pane, providing a set of four inner elements (31c, 32c, 33c, 34c), providing a set of four intermediate elements (31b, 32b, 33b, 34b), providing a set of two generally L-shaped corner keys with two perpendicular legs (39a1) divided by a channel (39a2), placing the longitudinal profiles in an upside-down position on an assembly table to form a profile element frame structure constituting three sides of a rectangle, placing a respective corner key within the longitudinal profiles at the mutually facing mitred ends, placing the pane within the profile element frame structure, and connecting the profile element structure to the inner elements (31c, 32c, 33c, 34c), optionally via the intermediate elements (31b, 32b, 33b, 34b), to form the sash. the frame comprises a set of frame members including a top frame member, two side frame members (22, 23) and a bottom frame member and the sash comprises a set of sash members including a top sash member, two side sash members (32, 33) and a bottom sash member, each frame and sash member defining a longitudinal direction, and the pane comprises a number of edge portions and an exterior pane surface defining a plane of the roof window in an assembled condition of the roof window, each sash member (31, 32, 33, 34) comprising a profile element (31a, 32a, 33a, 34a), an inner element (31c, 32c, 33c, 34c) and an intermediate element (31b, 32b, 33b, 34b) forming a connection between the profile element and the inner element of each sash member in an assembled condition of the sash, the profile elements (31a, 32a, 33a, 34a) of the sash members (31, 32, 33, 34) being located along respective exterior edge portions of the pane in the assembled condition of the sash, and the profile elements (31a, 32a, 33a) of the top sash member and the two side sash members (32, 33) being formed as a set of longitudinal profiles of substantially uniform cross-section, comprising the steps of: providing a set of three longitudinal profiles, optionally from a single profile length, forming mitre shapes at mutually facing ends of the longitudinal profiles, optionally such that the three longitudinal profiles are coherent, providing a pane, providing a set of four inner elements (31c, 32c, 33c, 34c), providing a set of four intermediate elements (31b, 32b, 33b, 34b), providing a set of two generally L-shaped corner keys with two perpendicular legs (39a1) divided by a channel (39a2), placing the longitudinal profiles in an upside-down position on an assembly table to form a profile element frame structure constituting three sides of a rectangle, placing a respective corner key within the longitudinal profiles at the mutually facing mitred ends, placing the pane within the profile element frame structure, and connecting the profile element structure to the inner elements (31c, 32c, 33c, 34c), optionally via the intermediate elements (31b, 32b, 33b, 34b), to form the sash. providing a set of three longitudinal profiles, optionally from a single profile length, forming mitre shapes at mutually facing ends of the longitudinal profiles, optionally such that the three longitudinal profiles are coherent, providing a pane, providing a set of four inner elements (31c, 32c, 33c, 34c), providing a set of four intermediate elements (31b, 32b, 33b, 34b), providing a set of two generally L-shaped corner keys with two perpendicular legs (39a1) divided by a channel (39a2), placing the longitudinal profiles in an upside-down position on an assembly table to form a profile element frame structure constituting three sides of a rectangle, placing a respective corner key within the longitudinal profiles at the mutually facing mitred ends, placing the pane within the profile element frame structure, and connecting the profile element structure to the inner elements (31c, 32c, 33c, 34c), optionally via the intermediate elements (31b, 32b, 33b, 34b), to form the sash.