Actions Requiring a Certificate of Appropriateness. A Certificate of Appropriateness issued by the Historic Preservation Commission shall be required before a permit is issued for any of the following, or, in the event no other type of permit is otherwise required, before any work can commence on any of the following activities on the property of any historic landmark:
1. Demolition of a landmark or of any improvement within any landmark district.
2. Relocation of any landmark or of any improvement within any landmark district.
3. Change in the exterior appearance of any existing landmark of any improvement within any landmark district by addition, alteration or replacement.
4. Any new construction, alteration, repair or remodeling of a principal or accessory structure of any landmark.
5. The subdivision or resubdivision of any landmark within any landmark district.
6. Changes in or addition of new signs or exterior lighting, except that no Certificate of Appropriateness shall be required for one unlit sign per premises if the surface area of such sign does not exceed 1 1/2 square feet.