Permitted Obstructions in Open Space

R1 R2 R3 R4 R5 R6 R7 R8 R9 R10

In the districts indicated, the following obstructions shall be permitted in any open space required on a zoning lot:

(a)        Air conditioning condensation units, accessory, for single- or two-family residences, provided that such units, if located between a street wall, or prolongation thereof, and a street line, are not more than 18 inches from a street wall, and fully screened from the street by vegetation;

(b)        Awnings and other sun control devices. However, when located at a level higher than the first story, excluding a basement, all such devices:

(1)        shall be limited to a maximum projection from a building wall of 2 feet, 6 inches; and

(2)        shall have solid surfaces that, in aggregate, cover an area no more than 30 percent of the area of the building wall (as viewed in elevation) from which they project;

(c)        Balconies, unenclosed, subject to the provisions of Section 23-13;

(d)        Breezeways;

(e)        Driveways, private streets, open accessory off-street parking spaces, unenclosed accessory bicycle parking spaces or open accessory off-street loading berths, provided that the total area occupied by all these items does not exceed the percentages set forth in Section 25-64 (Restrictions on Use of Open Space for Parking);

(f)        Eaves, gutters or downspouts, projecting into such open space not more than 16 inches or 20 percent of the width of such open space, whichever is the lesser distance;

(g)        Exterior wall thickness, where such wall thickness is added to the exterior face of a building wall existing on April 30, 2012, provided the added wall thickness has a thermal resistance (R-value) of at least 1.5 per inch, and is limited to one inch of thickness for every foot of existing open space width, up to a maximum thickness of eight inches;

(h)        Parking spaces, off-street, enclosed, accessory, not to exceed one space per dwelling unit, when accessory to a single-family, two-family or three-family residence, provided that the total area occupied by a building used for such purposes does not exceed 20 percent of the total required open space on the zoning lot. However, two such spaces for a single-family residence may be permitted in lower density growth management areas and in R1-2A Districts;

(i)        Accessory power systems, including, but not limited to, generators, solar energy systems, fuel cells, batteries and other energy storage systems, provided that:

(1)        all equipment shall be subject to the following location, enclosure, and screening requirements, as applicable:

(i)        all generators and cogeneration equipment accessory to buildings other than single- or two-family residences shall be completely enclosed within a building or other structure, except as necessary for mechanical ventilation;

(ii)        all other types of equipment, including generators and cogeneration equipment serving single- or two-family residences, may be unenclosed, provided that such equipment is located at least five feet from any lot line. However, if the area bounding all such equipment, as drawn by a rectangle from its outermost perimeter in plan view, exceeds 25 square feet, such equipment shall be screened in its entirety on all sides. Such screening may be opaque or perforated, provided that where perforated materials are provided, not more than 50 percent of the face is open;

(iii)        where any equipment is located between a street wall, or prolongation thereof, and a street line, the entire width of such portion of the equipment facing a street, whether open or enclosed, shall be fully screened by vegetation; and

(2)        the size of all equipment, including any screening or portions of any building or other structure enclosing such equipment, shall not exceed:

(i)        an area equivalent to 25 percent of a required open space;

(ii)        in R1 through R5 Districts, a height of 10 feet above the adjoining grade; and

(iii)        in R6 through R10 Districts, a height of 15 feet above the adjoining grade.

(j)        Ramps or lifts for people with physical disabilities;

(k)        Solar energy systems:

(1)        on the roof of an accessory building, limited to 18 inches in height as measured perpendicular to the roof surface; or

(2)        on walls existing on April 30, 2012, projecting no more than 10 inches and occupying no more than 20 percent of the surface area of the building wall (as viewed in elevation) from which it projects;

(l)        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;

(m)        Terraces, unenclosed, fire escapes or planting boxes, provided that no such items project more than six feet into or over such open space.

However, any such open space that is part of a required yard, rear yard equivalent or court may contain an obstruction listed in this Section only where such obstruction is permitted, pursuant to Sections 23-44 (Permitted Obstructions in Required Yards or Rear Yard Equivalents) or 23-87 (Permitted Obstructions in Courts), as applicable.