Appearance, design and construction. Nothing herein shall be construed to alter the dimensional regulations applicable in the district where any upper floor dwelling unit is proposed, including, without limitation, the regulation of height, area, location, or performance characteristics of any structure or other improvement. Buildings which are altered in order to contain one or more upper floor dwelling units shall maintain the exterior appearance of the use located below the upper floor dwelling unit(s). Upper floor dwelling unit(s) may be served by a shared ground-level entryway, centralized mailbox area, staircase, stair tower, and landings but two or more upper floor dwelling units shall not share any interior corridor, interior common trash facilities, common lounges or meeting rooms, common deck(s), common pools, hot tubs, or spas, or any other common amenities.