(a) A non-conforming building may be enlarged or extended only if the entire building is thereafter devoted to a conforming use and is made to conform to all the regulations of the district in which it is located.
(b) No building partially occupied by a non-conforming use shall be altered in such a way as to permit the enlargement or expansion of the space occupied by such non-conforming use.
(c) No non-conforming use may be enlarged or extended in such a way as to occupy any required usable open space, or any land beyond the boundaries of the zoning lot as it existed on the effective date of this Zoning Code, or to displace any conforming use in the same building or on the same parcel.
(d) A building or structure which is non-conforming with respect to yards, floor area ratio, or any other element of bulk regulated herein, shall not be altered or expanded in any manner which would increase the degree or extent of its non-conformity with respect to the bulk regulations of the district in which it is located.
(1977 Code § 73-307)