A floor structure comprises a flooring arranged on top of a lower and an upper layer of parallel joists with a uniform mutual distance, the joists of one layer extending substantially perpendicular to the joists of the second layer. The lower layer of joists are arranged on chocks, at least one of which is located below the center between the upper joists arranged thereabove. Resilient spring elements are provided at the intersections between the two layers of joists. The layers of joists include prefabricated identical members fitting in one another, each member comprising a predetermined number of joists. The joists of the lower layer are equally long and project by half the joist distance of the upper layer of joists beyond the outermost joist at the adjacent end of the upper layer of joists. The joists of the upper layer are also equally long, but interconnected in such a manner that one end of some of the upper joists ends substantially at the center of a spring element on the adjacent outermost joist in the lower layer of joists, such that the corresponding ends of the remaining upper joists project beyond the adjacent outermost joist by a length substantially corresponding to the sum of the joist distance of the lower layer of joists and half the width of a lower joist measured in the longitudinal direction of the upper joist.