Approval of an administrative adjustment shall be valid for one year from the date the administrative adjustment was granted for the purposes of obtaining such additional approvals as are required, including, but not limited to, site plan, conditional use permit, special use permit, certificate of appropriateness and a building permit. Failure to secure the required approvals or a building permit during the one-year period shall cause the administrative adjustment to become null and void. Upon application, the Building Inspector or designee may grant an extension of the administrative adjustment for a period not to exceed one year. Up to two extensions may be granted, for a total time period of all extensions of no more than two years.