Abstract: A joist to be used as a top joist in a sporting floor in which a plurality of floor boards (1) or panels rest on a plurality of parallel top joists (3). The top joists (3) are spaced apart and rest on a plurality of parallel, spaced-apart bottom joists (4) extending substantially perpendicular to the top joists (3) and supported on a base (5) by means of blocks (6). The top joist has a narrow, upper flat surface (7) extending along the joist and adapted to engage the lower side of the floor boards or panels, and a narrow, lower flat surface (8) which extends along the joist and which is positioned directly opposite the upper flat surface and adapted to engage the upper side of the bottom joists (4). The joist has a thickness decreasing laterally outwards from these two flat surfaces (7, 8).