A nonconforming use may be continued but shall not be enlarged or extended. A structure constituting or containing a nonconforming use shall not be enlarged, extended or structurally altered, or repaired if damaged by any casualty to an extent exceeding 50% of the assessed value of such structure at the time of damage, except for a conforming use. If any nonconforming building used as a single-family dwelling is destroyed or damaged to an extent exceeding 50% of its true value, the same may be reconstructed within one year after such destruction or damage so as to occupy the same space that it occupied prior to such destruction or damage.

A nonconforming use discontinued for a period of one year or changed to a conforming use shall be considered abandoned, and such nonconforming use shall not be reestablished.

Normal maintenance and repair, structural alteration, and moving, reconstruction or enlargement of a single-family home which does not house a nonconforming use, but is a nonconforming structure as to the district regulations, is permitted if the same does not increase the degree of or create any new nonconformity with such regulations in such building.

Any structure or portion thereof declared unsafe by a proper authority may be restored to a safe condition.