A system for applying a building material, including: a movement device for modifying a site of application in a space; a first component of the building material; a second component of the building material; and a mixer for mixing the first component and the second component, the mixer including a drive and a mixing chamber provided with a stirrer shaft and a conveyor device, the conveyor device being designed as a screw conveyor with windings, and the mixer being adapted to the building material.