Modern architecture goes hand in hand with increasing challenges for structural engineers. The efforts being made to create ceilings with as wide a span as possible and few load-bearing elements are constantly increasing. As a consequence, architects are receiving ever more freedom in designing floor plans. For this purpose, the Department of Structural Design and Timber Engineering at TU Wien (Vienna University of Technology) is developing a composite slab system consisting of concrete, lightweight wood concrete and wood. The three layers with different characteristics of their materials are used to the best possible effect. In this thesis, the long-term load-bearing behaviour of the composite system is described by means of component testing and via calculations. The finite element method is used as the basis of the calculations. The finite element model is verified by recalculating previous research results. The influence of various characteristics of materials, varying layer height and the position of the connecting devices is analysed in the form of a parameter study. As the superordinate objective of this master-s thesis, creep coefficients are then determined which make it possible to calculate the composite system, taking into account long-term deformation. Finally, a dimensioning table is developed to determine the suitable composite section for specific loads and lengths of span with little effort.