Except as otherwise provided in this article, the lawful use of land or buildings existing at the date of the adoption of this chapter may be continued although such use or building does not conform to the regulations specified by this chapter for the zone in which such land or building is located; provided, however, that:
A. 
No nonconforming lot shall be further reduced in size.
B. 
No nonconforming building shall be enlarged, extended or increased unless such enlargement would tend to reduce the degree of nonconformance.
C. 
No nonconforming use may be expanded.
A nonconforming use shall be deemed abandoned when there occurs a cessation of any use or activity by an apparent act of failure to act on the part of the tenant or owner to reinstate such use within a period of one year from the date of cessation or discontinuance.
No building damaged by fire or other causes to the extent of more than 50% of its assessed valuation shall be repaired or rebuilt except in conformity with the regulations of this chapter. Nothing in this chapter shall prevent the strengthening or restoring to a safe condition any wall, floor or roof which has been declared unsafe by the Code Enforcement Officer.
No nonconforming use shall, if once changed into a conforming use, be changed back again to a nonconforming use.
A nonconforming building may not be reconstructed or structurally altered during its life to an extent exceeding in aggregate cost 50% of the assessed value of the building unless said building is changed to conform to the requirements of this chapter.
Whenever the boundaries of a district shall be changed so as to transfer an area from one district to another of a different classification, the foregoing provisions shall also apply to any nonconforming uses existing therein or created thereby.
Nothing herein contained shall require any change in plans, construction or designated use of a building, structure or sign for which a building permit has heretofore been issued and the construction of which shall have been diligently prosecuted within three months of the date of such permit, and the ground story framework of which, including the second tier of beams, shall have been completed within six months of the date of the permit, and which entire building shall be completed according to such plans as filed within one year from the date of the adoption of this chapter.