§ 29. Painting of courts and shafts. The exterior surface of all walls of all courts and shafts of multiple dwellings, except of outer courts opening on a street, and courts having dimensions of at least fifty percent in excess of the minimum set forth in section twenty-six, shall be of a lightcolored brick or stone, or be thoroughly whitewashed or painted a light color by the owner and be so maintained. Such whitewash or paint shall be renewed whenever necessary, as may be determined and required by the department.