Abstract: Device for joining board-shaped elements into one unit with the board-shaped elements extending in a substantially parallel relationship to each other and internally separated by an intermediate gap, has a coupling list abutting adjacent parallel edge portions of the board-shaped elements with members extending towards and engaging with the edge portions. According to the invention, the coupling list includes at least one tension member extending from the side of the coupling list that abuts the edge portions of the board-shaped elements and the tension member is arranged to engage with at least one tightening element extending between the board-shaped elements which when manually rotated is arranged to impose a tightening force unto the tension member causing the coupling list to be pressed against the edge portions of the board-shaped elements.