A one-piece plastics material mesh structure (1), particularly a geogrid for use in geoengineering construction, is produced by stretching a plastics sheet starting material (20) formed with an array of holes (21). The mesh structure (1) comprises a plurality of generally parallel rib structures (2) extending longitudinally in a first direction parallel to the stretch direction (MD) and a plurality of generally parallel bar structures (3) extending in a second direction (TD) transverse to the rib structures (2). The rib structures (2) and said bar structures (3) are interconnected by junctions (5) at spaced locations along their respective lengths whereby the rib structures (2) are sub-divided along their length into alternating junctions (5) and rib segments (6) and the bar structures are sub-divided along their lengths by alternating bar segments (7) and junctions (5). In the mesh structure (1), (a) the rib structures (2) are such that the rib segments (6) are oriented in the first direction (MD) along their lengths and orientation in the first direction (MD) extends across the junctions (5) connecting two such oriented rib segments, and (b) the bar structures (3) are such that their overall stretch ratio in the second direction (TD) is a maximum of 1 and all locations along the length of the bar structures (3) have a maximum orientation of 1.5 in the second direction (TD).