The following provisions shall apply to all buildings and uses existing on the effective date of this chapter, which buildings and uses do not conform to the requirements set forth in this chapter; to all buildings and uses that become nonconforming by reason of any subsequent amendment to this chapter and the Zoning Map which is a part thereof; and to all conforming buildings housing nonconforming uses:
A. 
Any nonconforming use may be continued indefinitely, but:
(1) 
Shall not be enlarged, extended, reconstructed or placed on a different portion of the lot or occupied by such uses on the effective date of this chapter, nor shall any external evidence of such use as traffic, noise, vibration, smoke, dust, odors, heat or glare be increased by any means whatsoever.
(2) 
Shall not be changed to another nonconforming use without a special permit from the Board of Adjustment and then only to a use which, in the opinion of such Board, is of the same or a more restricted nature, all with approval of the Mayor and Council.
(3) 
Shall not be reestablished if such use has been discontinued for any reason for a period of one year or more or has been changed to or replaced by a conforming use. Intent to resume a nonconforming use shall not confer the right to do so.
B. 
Except as provided in Subsection D below, no building which houses a nonconforming use shall be:
(1) 
Structurally altered or enlarged.
(2) 
Moved to another location where such use would be nonconforming.
(3) 
Restored for other than a conforming use after damage from any cause exceeding 50% of the replacement cost of such building, exclusive of foundations. Any such building damaged to a lesser extent may be restored, but not enlarged, and the nonconforming use reinstated within one year of such damage. If the restoration of such building is not completed within the one-year period, the nonconforming use of such building shall be deemed to have been discontinued.
C. 
Normal maintenance and repair, structural alteration in and moving, reconstruction or enlargement of a building which does not house a nonconforming use, but is nonconforming as to the zone regulations for lot area, lot width, front yard, side yard, rear yard, maximum height, maximum lot coverage or minimum livable floor area per dwelling, is permitted if the same does not increase the degree of, or create any new nonconformity with such regulations in such building.
D. 
Nothing in this chapter shall be deemed to prevent normal maintenance and repair of any building or the carrying out, upon the issuance of a building permit, of major structural alterations or demolitions necessary in the interest of public safety. In granting such a permit, the Building Inspector shall state the precise reason why such alterations were deemed necessary.