A plant (100) for the layered construction of a molded body comprises a coating device (400) and a coating device cleaner (600). The coating device is movable horizontally across a construction field for applying a uniform layer of construction material to be solidified to the construction field and has an elongate metering shaft (410), at the lower side of which a longitudinal slot (412) is provided for outputting the construction material as the metering shaft (410) moves across the construction field. The coating device cleaner (600) is mounted on a construction frame (150) of the plant and serves for cleaning the metering shaft (410). The coating device cleaner (600) comprises an elongate wiper element (610) that is received under the metering shaft (410) of the coating device (400) at least in part in a construction material collection container (620).