No land or building shall be used and no building, structure, or improvement shall be made, erected, constructed, moved, altered, enlarged, or rebuilt which is designed, arranged, or intended to be used or maintained for any purpose or in any manner except in accordance with the use, height, area, yard, space, and other requirements established in the district in which such land, building, structure, or improvement is located, except as provided by chapter 13 of this title. In order to avoid undue hardship:
A. Nothing in this title shall be deemed to require a change in the plans, construction, or designated use of any building, where a building permit was lawfully issued prior to the effective date of this title, and pursuant to such permit, construction is diligently carried to completion. Upon completion, such building or use shall be deemed nonconforming and may continue as regulated by chapter 13 of this title.
B. At any time within two (2) years after the effective date hereof, a building permit and zoning clearance permit may be issued or a use of land commenced in accordance with the terms and conditions of a special exception or variance granted by the board of adjustment prior to the effective date hereof. (1991 Code § 16-12-204)