When a property owner shows that a strict application of the terms of the zoning regulations of this code relating to the use, construction or alteration of buildings or structures, or to the use of land, imposes upon him practical difficulties or particular hardship, then the board may make such variations of the strict application of the terms of said zoning regulations as are in harmony with its general purpose and intent when the board is satisfied, under the evidence heard before it, that a granting of such variation will not merely serve as a convenience to the applicant, but it is necessary to alleviate some demonstrable hardship or difficulty so great as to warrant a variation. (1982 Code § 2-3-6)