Abstract: The invention concerns a prefabricated composite construction system for the production of internal and/or external building-walls. The composite construction system has a building panel for internal use of wooden material and a building panel for external use of a heat-insulating hard cellular material. Between the panels spacers are provided which are connected with them and form voids, which can be filled with concrete, in which steel lattices are arranged on the building panel for internal use which extend in concrete chuting direction.