In all Residence Districts, the obstructions set forth in Section 23-441 (General permitted obstruction allowances), as well as the following obstructions, shall be permitted within a required yard or rear yard equivalent:

1. In any yard or rear yard equivalent:
   1. Balconies, unenclosed, of a building containing residences subject to the applicable provisions of Section 23-13. Such balconies are not permitted in required side yards;
   2. Fences, not exceeding four feet in height above adjoining grade in any front yard, except that for corner lots a fence may be up to six feet in height within that portion of one front yard that is between a side lot line and the prolongation of the side wall of the residence facing such side lot line;
   3. Fire escapes, projecting into a front yard, only in such cases where the fire escape is required for the conversion of a building in existence before December 15, 1961;
   4. Overhanging portions of a building in R4 and R5 Districts, except R4-1, R4A, R4B, R5A, R5B or R5D Districts, which are above the first story including the basement and which project not more than three feet into the required 18-foot front yard. In no case shall the lowest level of the projected portion be less than seven feet above the level of the front yard at the face of the building. Supports for the projected portion of any building are permitted obstructions within the required front yard, provided that the total area occupied by such supports does not exceed 15 percent of the area underneath the projected portion. No support may extend beyond the three-foot projection
   5. Parking spaces for automobiles, off-street, open, accessory, within a side or rear yard;
   6. Parking spaces, off-street, open, within a front yard, that are accessory to a building containing residences, provided that:
      1. in R1, R2, R3-1, R3A, R3X, R4-1, R4A and R5A Districts, except in lower density growth management areas, such spaces meet all the requirements of paragraph (a) of Section 25-621 (Location of parking spaces in certain districts);
      2. in R3-2 Districts, R4 Districts other than R4-1, R4A and R4B Districts, and R5 Districts other than R5A, R5B and R5D Districts, such spaces meet all the requirements of paragraph (b) of Section 25-621;
      3. in lower density growth management areas, such spaces are non-required and are located in a driveway that accesses parking spaces that are located behind the street wall of the building or prolongation thereof;
         
         However, no parking spaces of any kind shall be permitted in any front yard in an R4B, R5B or R5D District. Furthermore, no parking spaces of any kind shall be permitted in any front yard on a zoning lot containing an attached or semi-detached building in an R1, R2, R3A, R3X, R4A or R5A District, or in any front yard on a zoning lot containing an attached building in an R3-1 or R4-1 District;
   7. Energy infrastructure equipment and accessory mechanical equipment, provided that:
      1. all equipment shall be subject to the applicable provisions of Section 26-60 (SPECIAL SCREENING AND ENCLOSURE PROVISIONS);
      2. the size of all equipment, including any screening or portions of any building or other structure enclosing such equipment, shall not exceed:
         1. an area equivalent to 25 percent of a required yard, or rear yard equivalent, and in addition, in front yards, is limited to an area not exceeding 25 square feet. However, for corner lots, one front yard may be treated as a side yard for the purpose of applying such size restrictions;
         2. in R1 through R5 Districts, a height of 10 feet above the adjoining grade in rear yards, rear yard equivalents and side yards, or a height of five feet above the adjoining grade in front yards; and
         3. in R6 through R10 Districts, a height of 15 feet above the adjoining grade;
   8. Steps, provided that such steps access only the lowest story or cellar of a building fronting on a street, which may include a story located directly above a basement;
   9. Swimming pools, accessory, above-grade structures limited to a height not exceeding eight feet above the level of the rear yard or rear yard equivalent. Accessory swimming pools are not permitted obstructions in any front yard;
   10. Walls, not exceeding eight feet in height above adjoining grade and not roofed or part of a building, and not exceeding four feet in height in any front yard, except that for corner lots, a wall may be up to six feet in height within that portion of one front yard that is between a side lot line and the prolongation of the side wall of the residence facing such side lot line;
2. In any rear yard or rear yard equivalent:
   1. Balconies, unenclosed, subject to the provisions of Section 23-13;
   2. Parking spaces, off-street, accessory, for automobiles or bicycles, provided that:
      1. if accessory to a single- or two-family residence, the height of a building containing such parking spaces shall not exceed 10 feet in height above the adjoining grade and such building shall be detached from such residence. Furthermore, if located in an R1 District, such building may not be nearer than five feet to a rear lot line or side lot line. In R2A Districts, detached garages shall be included in lot coverage;
      2. if accessory to any other kind of building containing residences, the height of a building, or portion thereof, containing such parking spaces within the rear yard, shall not exceed 10 feet above adjoining grade, including the apex of a pitched roof in R3, R4 or R5 Districts, or 15 feet above curb level or base plane, as applicable, in R6, R7, R8, R9 or R10 Districts. In addition, decks, parapet walls, roof thickness, skylights, vegetated roofs, and weirs, as set forth in Section 23-62 (Permitted Obstructions), limited to 18 inches in height, as measured perpendicular to the roof surface, shall be permitted upon the roof of such accessory building within the rear yard;
      3. enclosed accessory parking spaces for bicycles shall be accessory to a residence other than a single- or two-family residence, attached to a building, and the area dedicated to such spaces shall not exceed the area of bicycle parking spaces permitted to be excluded from floor area pursuant to Section 25-85 (Floor Area Exemption);
   3. any portion of a building used for residential uses other than dwelling units in Quality Housing buildings containing affordable independent residences for seniors on zoning lots meeting the criteria set forth in paragraph (a)(4) of Section 23-664 (Modified height and setback regulations for certain Inclusionary Housing buildings or affordable independent residences for seniors), provided that:
      1. such zoning lot is located in an R6 through R10 District other than an R6B, R7B or R8B District;
      2. the height of such building portion does not exceed one story, or 15 feet above the adjoining grade, whichever is less;
      3. such building portion is located within 100 feet of a wide street; and
      4. such space shall be accessible to all residents of the building. In addition, decks, parapet walls, roof thickness, skylights, vegetated roofs and weirs, as set forth in Section 23-62 (Permitted Obstructions), limited to 18 inches in height, as measured perpendicular to the roof surface, shall be permitted upon the roof of such portion of a building within the rear yard.

However, no portion of a rear yard equivalent which is also a required front yard or required side yard may contain any obstructions not permitted in such front yard or side yard.