A roof window for installation in a roof structure of a building, wherein the roof window comprises: - a frame arrangement comprising structural elongated frame profiles (2a-2d) that encloses a frame opening, wherein said frame profiles (2a-2d) each comprises a first exterior side facing the frame opening and a second exterior side facing away from the frame opening, - one or more holding members comprising a holding part, a wall part, and a fixation part, - an insulating glass unit comprising at least a first glass sheet and a second glass sheet, wherein an insulating gap is provided between a major surface (3a1) of the first glass sheet which faces the insulating gap and a major surface (3b2) of the second glass sheet which faces the insulating gap, where the insulating gap is sealed by means of an edge seal arranged between said major surface (3a1) of the first glass sheet and said major surface (3b2) of the second glass sheet, wherein a side portion of the major surface (3b2) of the second glass sheet extends with a distance past a part of the edge seal that faces away from the insulating gap so as to provide a space opposite to said side portion and where the space is located opposite to said part of the edge seal, said roof window being characterised in that: the frame arrangement supports the insulating glass unit and the insulating glass unit overlaps one or more of the frame profiles (2a-2d), the wall part overlaps a side edge of the second glass sheet, and the fixation part overlaps the second exterior side of the overlapped frame profile (2a-2d) and is attached to the overlapped frame profile (2a-2d) at the second exterior side, and the holding part extends into the space and provides a holding force towards the side portion so as to secure the insulating glass unit at the frame arrangement. - a frame arrangement comprising structural elongated frame profiles (2a-2d) that encloses a frame opening, wherein said frame profiles (2a-2d) each comprises a first exterior side facing the frame opening and a second exterior side facing away from the frame opening, - one or more holding members comprising a holding part, a wall part, and a fixation part, - an insulating glass unit comprising at least a first glass sheet and a second glass sheet, wherein an insulating gap is provided between a major surface (3a1) of the first glass sheet which faces the insulating gap and a major surface (3b2) of the second glass sheet which faces the insulating gap, where the insulating gap is sealed by means of an edge seal arranged between said major surface (3a1) of the first glass sheet and said major surface (3b2) of the second glass sheet, wherein a side portion of the major surface (3b2) of the second glass sheet extends with a distance past a part of the edge seal that faces away from the insulating gap so as to provide a space opposite to said side portion and where the space is located opposite to said part of the edge seal, said roof window being characterised in that: the frame arrangement supports the insulating glass unit and the insulating glass unit overlaps one or more of the frame profiles (2a-2d), the wall part overlaps a side edge of the second glass sheet, and the fixation part overlaps the second exterior side of the overlapped frame profile (2a-2d) and is attached to the overlapped frame profile (2a-2d) at the second exterior side, and the holding part extends into the space and provides a holding force towards the side portion so as to secure the insulating glass unit at the frame arrangement. the frame arrangement supports the insulating glass unit and the insulating glass unit overlaps one or more of the frame profiles (2a-2d), the wall part overlaps a side edge of the second glass sheet, and the fixation part overlaps the second exterior side of the overlapped frame profile (2a-2d) and is attached to the overlapped frame profile (2a-2d) at the second exterior side, and the holding part extends into the space and provides a holding force towards the side portion so as to secure the insulating glass unit at the frame arrangement.