(a) Because structures in the historic districts were often built close to the lot lines, it is in the public interest to retain the historic appearance of the Historic Districts by approving variances to normal yard requirements. Where it is deemed that such variance will not adversely affect neighboring properties, the Board of Zoning Appeals may grant such variance to standard requirements. New buildings shall be sited at a distance not more than five percent (5%) out-of- line from the setback of the existing adjacent buildings.