Within the zones established by this chapter or any amendments thereto, there exist lots, structures and uses of land and structures which were lawful before August 11, 1972, but which would be prohibited, regulated or restricted under the terms of this chapter or any future amendment.

It is the intent of this chapter to permit these nonconformities to continue until they are removed. Such uses are declared by this chapter to be incompatible with permitted uses in the zones involved. It is further the intent of this chapter that nonconformities shall not be enlarged upon, expanded or extended, nor be used as grounds for adding other structures or uses prohibited elsewhere in the same district.

A nonconforming use of a structure, a nonconforming use of land, or a nonconforming use of a structure and land shall not be extended or enlarged after August 11, 1972 by attachment on a building or premises of additional signs intended to be seen from off the premises or by the addition of other uses of a nature which would be prohibited generally in the zone involved.

To avoid undue hardship, nothing in this chapter shall be deemed to require a change in the plans, construction or designated use of any building on which actual construction was lawfully begun prior to August 11, 1972 or the date of any amendment of this chapter, and upon which actual building construction has been diligently carried on. Actual construction is hereby defined to include the placing of construction materials in permanent position and fastened in a permanent manner, except that where demolition or removal of an existing building has been substantially begun preparatory to rebuilding, such demolition or removal shall be deemed to be actual construction, provided that work shall be diligently carried on until completion of the building involved. The within grace period herein provided for shall not be construed to apply to any subsequent amendment of this chapter.