No land shall be used or occupied and no building hereafter erected, altered or extended shall be used or changed in use until a certificate of occupancy shall have been issued by the Code Enforcement Officer(s). Under such rules as may be established by the Board of Appeals, a temporary certificate of occupancy for not more than 30 days for a part of a building may be issued by the Code Enforcement Officer(s). For previously existing construction, the Code Enforcement Officer(s) may, on request, issue such a certificate if he determines that the use of the building in question meets the requirements of this chapter.