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.
New York Legal Code