No building, sign or other structure or land shall be used or occupied and no building or structure or part thereof shall be erected, constructed, reconstructed, moved, enlarged or structurally altered unless in conformity with the regulations of this chapter. However, this chapter shall not require any change to any building, structure or use legally existing at the effective date of this chapter, or any amendment thereto; or to any building, structure or use planned and construction started in compliance with existing laws prior to the effective date of this chapter, or any amendment thereto, and completed within a one-year period after the effective date of this chapter, or any amendment thereto, except as otherwise provided herein.