SEC. 270.3. SPECIAL BULK REQUIREMENTS: MID-BLOCK ALLEYS IN LARGE LOT DEVELOPMENT… — San Francisco County Zoning Code

(a) Findings. This Section 270.3 incorporates the findings in Section 270.2(a), and determines that the conditions in Section 270.2 are applicable outside of the geographic area specified in Section 270.2..1

(b) Purpose. The mid-block alley requirements of this Section 270.3 are intended to ameliorate the conditions and impacts described in the findings in Section 270.2(a) and make the subject areas appropriate for a higher density of activity and population in areas being targeted for more intense development. The horizontal mass reductions and midblock alleys will ensure that block sizes for new housing support walkable neighborhoods. To encourage pedestrian movement, walking to nearby destinations including to and from transit, and neighborhood blocks with shortened distances to facilitate this activity, the bulk limitations noted below will apply.

(c) Applicability. This Section 270.3 applies to all development lots not subject to the requirements of Section 270.2, except development lots in PDR districts or that contain exclusively government or Public Facilities, that:

(1) Are two acres or larger; and/or

(2) Have a frontage of 200 feet or greater on a single block face that is 400 feet or greater.

(d) Requirements. New construction on development lots that meet the criteria in subsection (c) above must be

divided into smaller resultant lots and blocks in either one of the two following ways:

(1) Option 1. Lots shall be divided into resultant blocks such that:
(A) no block frontage exceeds a length of 300 feet between intersections;
(B) no block perimeter exceeds a total of 1,200 feet; and

(C) the resultant blocks shall be separated from each other by newly created public street(s), alley(s), or publiclyaccessible privately-owned street(s) or alley(s). Such street(s) shall meet San Francisco street standards including the Better Streets Plan as codified in Section 138.1 and pursuant to Public Works Code requirements. If privately-owned street(s) or alley(s) are created, they shall be maintained and must provide public access pursuant to the standards provided in Planning Code Section 270.2(e).

(2) Option 2. Lots shall be divided into resultant blocks of not more than 400 feet in length between intersections of streets or alleys per subsection (d)(1)(C) above, that are bisected by alleys or passageways, and that do not exceed a total block perimeter of 1,400 feet. Such mid-block alleys or passageways shall meet the following conditions:

(A) Location. Be located as close to the middle portion of the subject block face, defined as within 50 lateral feet from the block centerline, perpendicular to the subject frontage and connecting to any existing adjacent streets and alleys. If the subject lot is not within the central portion of the block, the passageway shall cross the subject lot at its centerline or within 50 lateral feet from the lot centerline. For Development projects that include a Public Facility or are immediately abutting a parcel containing a Public Facility, this locational requirement shall not apply.

(B) Hours of Operation. The passageway(s) must be open to the public 24 hours a day, seven days a week. Fences and/or gates that would prevent public access at any point within the passageway(s) are prohibited.

(C) Width. The passageway(s) must maintain minimum width(s) of 20 feet measured from building-to-building at any point.

(D) Walking Width. Have a minimum clear walking width of 10 feet free of any obstructions in the case of a pedestrian-only right-of-way, and dual sidewalks each of not less than six feet in width with not less than four feet minimum clear width in the case of an alley with vehicular access.

(E) Open to the Sky. At least 60% of the passageway area must be open to the sky. Obstructions permitted within setbacks pursuant to Planning Code Section 136, that do not conflict with or obstruct the required walking width, may be located within the portion of the alley or passageway that is required to be open to the sky. All portions of the alley or pathway not open to the sky shall have a minimum clearance height from grade of 15 feet at all points. For Development Projects that include a Public Facility or are immediately abutting a parcel containing to a Public Facility, the required percent of the passageway area that must be open to the sky may be reduced to 50%.

(F) Topography. Changes in grade or steps are not permitted in an alley or passageway unless required by the natural topography and average grade.

(G) Frontage. Alleys or passageways must be fronted by active ground-floor uses, as defined in Section 145.1, for no less than 60% of their fronting length and in no case feature more than 50 continuous feet of inactive use(s) in any segment. For development projects that include a Public Facility or are immediately abutting a parcel containing a Public Facility, the required percent for active ground-floor uses may be reduced to 40% and may be unevenly distributed between the alley’s or passageway’s two sides.

(H) Visual access. Alleys or passageways must be configured to allow clear visual access from one end of the passageway through the development lot to its opposite end.

(e) Additional Requirements for Private Passageways and Alleys.

(1) Maintenance. Mid-block passageways and alleys required under this Section 270.3 shall be maintained at no public expense unless a publicly-accepted street or alley is created pursuant to subsection (d)(1) above. The owner of the property on which the alley or passageway is located shall maintain it by keeping the area clean and free of litter and by keeping it in an acceptable state of repair. Conditions intended to assure continued maintenance of the right-of-way for the actual lifetime of the building giving rise to the open space requirement may be imposed.

(2) Informational Plaque. Prior to issuance of a permit of occupancy, a plaque shall be placed in a publicly conspicuous location for pedestrian viewing. The plaque shall state the right of the public to pass through the alley and stating the name and address of the owner or owner’s agent responsible for maintenance. The plaque shall be of no less than 24 inches by 36 inches in size.

(3) Property owners providing a pathway or alley under this Section 270.3 shall hold harmless the City and County of San Francisco, its officers, agents, and employees, from any damage or injury caused by the design, construction, or maintenance of the right-of-way, and are solely liable for any damage or loss occasioned by any act or neglect in respect to the design, construction, or maintenance of the right-of-way.

(f) Any non-vehicular portions of such a passageway or alley, including sidewalks or other walking areas, seating areas, or landscaping, may count toward any open space requirements of this Code which permit publicly-accessible open space, provided that such space meets the standards of Section 135.

(Added by Ord. 245-25, File No. 250701, App. 12/12/2025, Eff. 1/12/2026, Oper. 1/12/2026) CODIFICATION NOTE

So in Ord. 245-25