The height and setback modifications of this Section shall apply as follows:

1. Permitted obstructions
   1. Easement volumes
      
      Any portion of an easement volume shall be considered a permitted obstruction within a required setback or above any maximum base height, maximum building height, or sky exposure plane set forth in height and setback regulations of this Resolution. Any easement volume, including any use or structure therein, shall be located at least 30 feet from any legally required window at the same level on the zoning lot.
   2. Dormers
      
      For Quality Housing buildings, as an alternative to the provisions of paragraph (c) of Section 23-623, dormers may be a permitted obstruction within a required front setback distance above a maximum base height, provided that the aggregate width of all dormers at the maximum base height does not exceed 40 percent of the width of the street wall of the highest story entirely below the maximum base height. Such dormers need not decrease in width as the height above the maximum base height increases. For the purposes of this paragraph, the width of the street wall shall be determined pursuant to the provisions of paragraph (a) of Section 66-233 (Special street wall modifications).
2. Special height and setback provisions for R5 Districts
   
   The requirements of Section 23-63 (Height and Setback Requirements in R1 Through R5 Districts) shall be modified for the portions of a building used for residential use, as follows:
   1. In Commercial Districts mapped within, or with a residential equivalent of an R5 District, the maximum height of a street wall before setback shall be 35 feet. Above such height, a setback of 10 feet shall be provided, and the maximum building height shall be 45 feet. Such provisions shall also apply to buildings utilizing the optional provisions for a predominantly built-up area; and
   2. In R5D Districts or Commercial Districts mapped within, or with a residential equivalent of an R5D District, the maximum building height shall be increased by 10 feet or one story, whichever is less.
3. Special height provisions for R6 through R10 Districts and certain Commercial and M1 Districts
   
   In R6 through R10 Districts, Commercial Districts mapped within or with a residential equivalent of such districts, C7 Districts, M1 Districts paired with R6 through R10 Districts, M1-6 Districts, and Manufacturing Districts with an A suffix, where maximum building height limitations apply, the maximum building height shall be increased by 10 feet, or one story, whichever is less.
   
   However, for zoning lots with an easement volume serving an above-grade mass transit station in R7 through R10 Districts, Commercial Districts mapped within or with a residential equivalent of such districts, C7 Districts, M1 Districts paired with R7 through R10 Districts, M1-6 Districts, and Manufacturing Districts with an A suffix, the maximum building height  shall be increased by 20 feet or two stories, whichever is less.