A.
Within the districts established by this chapter or amendments that may later be adopted, there exist lots, structures, and uses of land and structures which were lawful before this chapter was passed or amended but which would be prohibited, regulated, or restricted under the terms of this chapter or future amendment. It is the intent of this chapter to permit these nonconformities to continue until they are removed, but not to encourage their survival. Such uses are declared by this chapter to be incompatible with permitted uses in the districts 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 structure, a nonconforming use of land, or a nonconforming use of a structure and land shall not be extended or enlarged after passage of this chapter.
B.
Prior permits. Where a building permit for a building or structure was issued in accordance with law prior to the effective date of this chapter, or a future amendment, and provided that construction is begun within 90 days of such effective date and diligently prosecuted to completion, said building or structure may be completed in accordance with the approved plans on the basis of which the building permit has been issued and, further, may upon completion be occupied under a zoning certificate by the use for which originally designed.[1]