Abstract: A panel structure comprising boards and for instance serving as a floor or a panel, the boards being arranged on the same plane edge to edge. The boards are held together two by two by means of a joining moulding of a substantially T-shaped cross section. The transverse web of the joining moulding is provided with a plurality of holding teeth to both sides of the vertical web of said moulding. Each half of the transverse web projects into its longitudinal locking, relatively deep, and substantially smooth groove in a board. The width of the groove is slightly smaller than the thickness of said transverse web. The joining moulding is of a relatively soft material such as plastics or rubber. In this manner the panel structure is so simple to mount that the mounting can be carried out by unskilled persons. Without damaging the panel structure, the boards may work relative to each other when exposed to variations in air moisture and/or temperature.