Applicability. Except as otherwise provided in this article, the unlawful use of land or buildings existing at the date of the adoption of this code may be continued although such use or building does not conform to the regulations specified by this code for the zone in which such land or building is located; provided, however, that:
(1) No nonconforming lot shall be further reduced in size.
(2) No nonconforming building shall be enlarged, extended or increased unless such enlargement, approved by the Zoning Board of Appeals, would tend to reduce the degree of nonconformance.
(3) No nonconforming use may be expanded.