R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12

The minimum distance between legally required windows and walls or lot lines shall be as set forth in this Section.

For the purposes of this Section, abutting buildings on the same zoning lot shall be considered a single building.

1. Exceptions
   
   This Section shall not apply to legally required windows in buildings containing residences with a maximum height of 35 feet, as measured from base plane, and with a maximum of three dwelling units. 
2. Basic provisions
   
   The minimum distance between a legally required window and:
   1. any wall;
   2. a rear lot line, or vertical projection thereof; or
   3. a side lot line, or vertical projection thereof;
       

                   shall be 20 feet, measured in a horizontal plane at the sill level of, and perpendicular to, such window for the full width of the rough window opening.
      
      The obstructions permitted for any yard set forth in Section 23-311 shall be permitted in such minimum distance.

3. For shallow lots
   
   For interior lots, where the depth is less than 95 feet deep at any point, the minimum distance between a legally required window and a rear lot line, or vertical projection thereof, may be modified to equal the rear yard depth required for shallow lots pursuant to the provisions of Section 23-342 (Rear yard requirements). However, in no event shall such minimum distance between a legally required window and a rear lot line, or vertical projection thereof, be less than 10 feet.
4. Special provisions for R3 through R5 Districts
   
   In R3, R4 and R5 Districts, the minimum dimension between a legally required window and a side lot line shall be 15 feet. Such 15-foot dimension shall be measured in a horizontal plane perpendicular to the side lot line or vertical projection thereof. Furthermore, such area with a 15-foot dimension shall be open from its lowest level to the sky for the entire length of the side lot line. Only accessory mechanical equipment limited in depth to 18 inches from an exterior wall, chimneys, downspouts, eaves, qualifying exterior wall thickness, gutters, open accessory off-street parking spaces, ramps for access by people with disabilities, and steps shall be permitted obstructions in such open area, subject to the conditions set forth in Sections 23-311 or 23-312, provided that such obstructions, not including qualifying exterior wall thickness and accessory mechanical equipment, will not reduce the minimum width of the open area by more than three feet.