A nonconforming use may be continued subsequent to adoption of this chapter, but the structure shall not be enlarged or altered in a way which increases its nonconformity and the use shall not be enlarged or increased to occupy a greater land area. A structure or sign which is destroyed by an act of God, vandalism or accident may be restored.

A nonconforming use may be extended throughout any part of a building which was manifestly arranged or designed for such use at the time of adoption of this chapter. A nonconforming use may not be changed to another nonconforming use.

Nothing in this chapter shall be deemed to prevent the strengthening or restoring to a safe condition of any structure declared unsafe by a qualified public official.

A nonconforming structure or use may not be altered, rebuilt or resumed except in conformity with the regulations for the district in which it is located if: