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; a mixer for mixing the first component and the second component, the mixer including a drive module with a first coupling element and a mixing chamber module with a second coupling element, the drive module and the mixing chamber module being detachably embodied, and the drive module and the mixing chamber module being actively interconnected in an application state of the system by means of the coupling elements.