Unless otherwise specified by the Board of Adjustment, a decision on any appeal for a variance or application for a special permit shall expire without further notice if the applicant fails to obtain any necessary building permit or to comply with the conditions of an authorized permit within one year from the date of such decision.

An extension of time may be granted by the Board of Adjustment because of the occurrence of conditions unforeseen at the time of the original action. An application for an extension of time shall be subject to the same procedures as specified for the original issuance of the variance or special permit.