Recently the interest of architects grows in using cardboard for constructions. For the realization of any structure adequate knowledge of the mechanical properties of the building material is essential. For structural application the mechanical behaviour and the load bearing capacity have to be predictable as well. However, there is not enough information about the mechanical properties of cardboard in terms of a building material. Common numbers and codes are not established yet. In the presented PhD project the mechanical behaviour of cardboard and cardboard structures are investigated concerning structural application. Also a computational model based on the finite element method will be developed as a prediction tool. The project combines material testing, structural design and computational modelling. In this regard preliminary beams completely made of cardboard were designed and tested. In this paper the outline of the PhD thesis and the first outcome of the preliminary design of the beams are presented.