In all districts, the Board of Standards and Appeals may permit the expansion of a conforming use located within a building or other structure into a district where such use is not permitted, provided that the enlarged use is contained within a single block and the expansion of either the depth or the width of the conforming use is no greater than 50 percent of either the depth or width, respectively, of that portion of the zoning lot located in the district where such use is a conforming use, but in no case shall the area of the expansion exceed 50 percent of the area of the zoning lot located in the district where such use is a conforming use, and provided further that the following findings are made:

(a)        there is no reasonable possibility of expanding such use within the existing district where it is a conforming use;

(b)        such conforming use was in existence prior to January 6, 1965, or the date of any applicable subsequent amendment to the zoning maps; and

(c)        such expanded use is not so situated or of such character or size as to impair the essential character or the future use or development of the surrounding area.

In the case of a use which, at the time of application to the Board under the provisions of this Section, is already partially located in the more restricted district, where it is a non-conforming use, or which has extended into such district in accordance with the provisions of Section 77-11 (Conditions for Application of Use Regulations to Entire Zoning Lot), the maximum expansion to be permitted under the provisions of this Section shall be computed as 50 percent of the width or depth of that portion of the zoning lot located within the mapped boundary of the district where such use is a conforming use, and shall be measured from such mapped district boundary.

In every case where the Board permits such expansion, the building or other structure, or portion thereof, situated on the expanded portion of the zoning lot shall comply on such expanded portion with the applicable bulk regulations of the district in which such use is a conforming use and, subject to such compliance on the expanded portion of the zoning lot, the Board may permit such conforming use, even when located in an existing building or other structure which is non-complying, to expand across the district boundary in accordance with the provisions of this Section.

All the applicable regulations of the district in which such use is a conforming use shall apply on the entire zoning lot, or any portion thereof, to be occupied by such use and any special regulation applying along district boundaries shall apply along rear and side lot lines of the expanded zoning lot.

Where yard regulations are applicable, the Board may permit the expanded area to include, in addition to area permitted under other provisions of this Section, such area as is necessary for the required yards. However, such additional area shall not be counted as lot area for purposes of bulk computations.

The Board may prescribe appropriate conditions and safeguards to minimize adverse effects on the character of the district including requirements for adequate screening.