Any variance granted or approved by the zoning administrator involving the erection, alteration, or enlargement of a building or structure for which a building permit is required is null and void after the expiration of one year from date said variance is granted unless the applicant obtains a building permit within one year from date said variance is granted and thereafter the time provisions of the building permit so secured shall prevail. The zoning administrator for good cause shown, may extend said one year period for not longer than any additional six months upon application in writing being made before expiration of said variance. (Amended during the March 2009 supplement.)