Any lawful nonconforming use which existed at the time of passage of this Part 3 may be continued, and any existing building designed, arranged, intended or devoted to a nonconforming use may be reconstructed or structurally altered, subject to the following:
A. 
The alterations made to such building shall in no case exceed 100% of the value of the building, nor shall the building be enlarged, unless the use therein is changed to a conforming use.
B. 
No nonconforming use shall be extended at the expense of a conforming use.
C. 
A nonconforming use changed to a conforming use may not thereafter change back to a nonconforming use.
D. 
In the event that there is a cessation of operation of any nonconforming use for a period of 12 consecutive calendar months, the same shall be presumed to be an abandonment of such nonconforming use. Any subsequent exercise of such abandoned nonconforming use shall be deemed a violation of the terms of this Part 3.
Any lawful nonconforming lot which existed at the time of the passage of this Part 3 may continue, provided that the development or redevelopment of the lot must conform to this Part 3.
Any lawful nonconforming structure which existed at the time of the passage of this Part 3 may be continued subject to the following:
A. 
Alterations to the exterior of a structure are permitted, provided that they do not increase the nonconformity of a structure.
B. 
Structures which are destroyed or deteriorated to the extent that they must be reconstructed must meet the height, area, yard, setback and other bulk requirements of this Part 3.
C. 
In determining the nonconformity of a structure each bulk requirement shall be considered separately and the existence of one violation of bulk requirements shall not prevent the property owner from making alterations and/or improvements to other sections of the structure which meet the requirements of this Part 3.
Nothing in this Part 3 shall require any change in plans, construction or designated use of a building for which a building permit has been heretofore issued and construction diligently pursued within six months of the date of such permit.
Nothing in this Part 3 shall be interpreted as authorization for or approval of the continuance of the use of a structure or premises in violation of zoning regulations in effect at the time of the effective date of this Part 3.
The foregoing provisions of this article shall also apply to buildings, structures, land or uses which hereafter become nonconforming due to any reclassification of zone districts under this Part 3 or any subsequent change in the regulations of this Part 3.