A roof arrangement for a terrace canopy, wherein the roof arrangement comprises a frame and a panel arrangement (13, 21) attached to the frame, which frame comprises a transverse direction, a longitudinal direction, a top side, a bottom side and at least one transverse beam extending in the transverse direction, wherein the panel arrangement is provided with: - N panels (22 1, 22 2, 22 3,...) slidable in the longitudinal direction between a distributed position and a stacked position, wherein N is a natural number larger than one, wherein a 1 st panel of said N panels is, in the distributed position, nearest to said transverse beam in the longitudinal direction and wherein an N th panel of said N panels is, in the distributed position, furthest away from said transverse beam in the longitudinal direction, wherein each panel has a frame having a nearest beam and a farthest beam which are mutually substantially parallel and extend in the transverse direction, which nearest beam of a frame is nearer to said transverse beam than the farthest beam of said frame; and - (N-1) pairs of reinforcing ribs (24 1, 25 1, 24 2, 25 2,...) each comprising an upper and a lower reinforcing rib, wherein an i th panel of the N panels is provided at its farthest beam with the one reinforcing rib of a pair of reinforcing ribs of said (N-1) pairs of reinforcing ribs and an (i+1) th panel of the N panels is provided at its nearest beam with the other reinforcing rib of said pair of reinforcing ribs for any natural number i between 0 and N, wherein the sum of the heights of the upper and lower reinforcing ribs of each pair of reinforcing ribs is substantially the same, wherein, in the distributed position of the panels, the frames of any two adjacent panels of said N panels extend in a different substantially horizontal plane, and wherein, in the distributed position of the panels, the bottom sides of all lower reinforcing ribs are in a first substantially horizontal plane (α) and the top sides of all upper reinforcing ribs are in a second substantially horizontal plane (β), which first plane is substantially parallel to the second plane. - N panels (22 1, 22 2, 22 3,...) slidable in the longitudinal direction between a distributed position and a stacked position, wherein N is a natural number larger than one, wherein a 1 st panel of said N panels is, in the distributed position, nearest to said transverse beam in the longitudinal direction and wherein an N th panel of said N panels is, in the distributed position, furthest away from said transverse beam in the longitudinal direction, wherein each panel has a frame having a nearest beam and a farthest beam which are mutually substantially parallel and extend in the transverse direction, which nearest beam of a frame is nearer to said transverse beam than the farthest beam of said frame; and - (N-1) pairs of reinforcing ribs (24 1, 25 1, 24 2, 25 2,...) each comprising an upper and a lower reinforcing rib, wherein an i th panel of the N panels is provided at its farthest beam with the one reinforcing rib of a pair of reinforcing ribs of said (N-1) pairs of reinforcing ribs and an (i+1) th panel of the N panels is provided at its nearest beam with the other reinforcing rib of said pair of reinforcing ribs for any natural number i between 0 and N, wherein the sum of the heights of the upper and lower reinforcing ribs of each pair of reinforcing ribs is substantially the same, wherein, in the distributed position of the panels, the frames of any two adjacent panels of said N panels extend in a different substantially horizontal plane, and wherein, in the distributed position of the panels, the bottom sides of all lower reinforcing ribs are in a first substantially horizontal plane (α) and the top sides of all upper reinforcing ribs are in a second substantially horizontal plane (β), which first plane is substantially parallel to the second plane.