If the work described in any building permit has not been substantially completed within one year of the date of issuance thereof, said permit shall expire and be cancelled by the administrative official, and written notice thereof shall be given to the persons affected, together with notice that further work as described in the cancelled permit shall not proceed unless and until a new building permit has been obtained. A building permit may be extended beyond one year if it is so requested in writing at the time of issuance of building permit.
(Prior Code, Art. 21, § 21-110.5)