The provisions of this chapter shall be known as the S-17 residential open space combining zone regulations. The S-17 zone is intended to provide open space standards for residential development that are appropriate to the unique density, urban character and historic character of the central business district. These regulations shall apply in the S-17 zone, and are supplementary to the regulations applying in the zones with which the S-17 zone is combined. (Ord. 12343 § 2 (part), 2001)

The S-17 zone may be combined with the portion of any zoning district that is located within the General Plan-designated Central Business District. (Ord. 12776 § 3, Exh. A (part), 2006: Ord. 12343 § 2 (part), 2001)

As used in this chapter, the following words will have the meaning set forth unless the context clearly indicates otherwise:
Usable open space categories shall be defined as follows:
A. Private Usable Open Space. Private usable open space is accessible from a single unit and may be provided in a combination of recessed and projecting exterior spaces.
B. Public Ground-Floor Plaza. Public ground-floor plazas (plazas) are group usable open space located at street-level and adjacent to the building frontage. Plazas are publicly accessible during daylight hours and are maintained by the property owner. Plazas shall be landscaped and include pedestrian and other amenities, such as benches, fountains and special paving.
C. Widened Sidewalk. A widened sidewalk includes paving, landscaping and pedestrian amenities along the building frontage and within the property boundaries, and constitutes group usable open space. A widened sidewalk shall involve either a land dedication or easement to allow public access at all times and a seamless connection to the public right-of-way.
D. Rooftop Open Space. Rooftop open space, a type of group usable open space, includes gardens, decks, swimming pools, spas and landscaping located on the rooftop and accessible to all tenants.
E. Courtyard. A courtyard is a type of group usable open space that can be located anywhere within the subject property.
F. Off-site Open Space. Privately owned and maintained group usable or public open space at ground-floor or podium level within one thousand (1,000) feet of a residential development, intended to fulfill the usable open space requirement of said residential development, only. (Ord. 12776 § 3, Exh. A (part), 2006: Ord. 12343 § 2 (part), 2001)

Residential development in the S-17 downtown residential open space combining zone shall provide a combination of the following usable open space categories, as defined in Section 17.99.030, in order to satisfy the standards established in Section 17.99.050:
A. Private usable open space;
B. Public ground-floor plaza;
C. Widened sidewalk;
D. Rooftop open space;
E. Courtyard; and
F. Off-site open space. (Ord. 12343 § 2 (part), 2001)

All required usable open space shall be permanently maintained and shall conform to the following standards:
A. Area. On each lot containing residential facilities with a total of two or more living units, usable open space shall be provided for such facilities at a rate of seventy-five (75) square feet per standard unit, fifty (50) square feet per efficiency unit, and thirty-eight (38) square feet per rooming unit.
B. Limitations. Not more than twenty (20) percent of the required area shall be provided in widened sidewalks.
C. Size and Shape. An area of contiguous space shall be of such size and shape that a rectangle inscribed within it shall have no dimension less than the dimensions shown in the following table:

* Measurement does not include width of existing sidewalk, and is additive to existing sidewalk.

When space is located on a roof, the area occupied by vents or other structures which do not enhance usability of the space shall not be counted toward the above dimension.
D. Openness. There shall be no obstructions above the space except for devices to enhance its usability, such as pergola or awning structures. There shall be no obstructions over ground-level private usable open space except that not more than fifty (50) percent of the space may be covered by a private balcony projecting from a higher story. Above-ground-level private usable open space shall have at least one exterior side open and unobstructed, except for incidental railings or balustrades, for eight feet above its floor level.
E. Usability. A surface shall be provided which prevents dust and allows convenient use for outdoor activities. Such surface shall be any practicable combination of lawn, garden, flagstone, wood planking, concrete, asphalt or other serviceable, dustfree surfacing. Slope shall not exceed ten percent. Off-street parking and loading areas, driveways, and service areas shall not be counted as usable open space. Adequate safety railings or other protective devices shall be erected whenever necessary for space on a roof, but shall not be more than four feet high.
F. Accessibility. Usable open space, other than private usable open space and off-site open space, shall be accessible to all the living units on the lot. It shall be served by any stairway or other accessway qualifying under the Oakland Building Code as an egress facility from a habitable room. Private usable open space may be located anywhere on the lot except that ground-level space shall not be located in a required minimum front yard and except that above-ground-level space shall not be located within five feet of an interior side lot line. Above-ground-level space may be counted even though it projects beyond a street line. All private usable open space shall be adjacent to, and not more than four feet above or below the floor level of, the living unit served. Private usable open space shall be accessible to only one living unit by a doorway to a habitable room or hallway.
G. Enclosure. Ground-level usable open space shall be screened from abutting lots, streets, alleys, and paths, from abutting private ways described in Section 17.106.020, and from other areas on the same lot by a building wall, by dense landscaping not less than five and one-half feet high and not less than three feet wide, or by a solid or grille, lumber or masonry fence or wall not less than five and one-half feet high, subject to the standards for required landscaping and screening in Chapter 17.124 and the exceptions stated in said chapter. However, when such screening would impair a beneficial outward and open orientation or view, with no building located opposite and within fifty (50) feet from such required screening, as measured perpendicularly therefrom in a horizontal plane, the above prescribed height may be reduced to three and one-half feet. Fences and walls shall not be constructed as to interfere with the access required by applicable fire prevention regulations. (Ord. 12343 § 2 (part), 2001)

At least ten percent of usable open space area (with the exception of private usable open space) shall include landscaping enhancement as well as user amenities. Landscaping shall consist of permanent features, such as trees, shrubbery, decorative planting containers and coverings (mulch, gravel), fountains, boulders or artwork (sculptures, murals). User amenities shall include seating, decorative paving or playground structures. (Ord. 12343 § 2 (part), 2001)

Usable open space areas shall be designed to be consistent with any design guidelines adopted for the affected zone. (Ord. 12343 § 2 (part), 2001)