Chéngguǎn xiàn tāmen yí ge yuè nèi chāichú wéijiàn.
The city inspectors gave them a month to tear down the illegal structure.
Tips
usage
Short for 违章建筑: anything built without a permit, from rooftop huts to whole extra floors. Typical news phrases are 拆违建 "tear down illegal structures" and 查违建 "inspect for illegal structures".