Planning Director Bulletin No. 8: Streamlined Housing Development
This Bulletin is an overview of two ministerial streamlining programs for small residential projects:
- Senate Bill 9 allows duplexes and lot splits for certain parcels in single family (RH-1) zoning districts
- Senate Bill 684 allows up to 10 units on certain parcels
First Issued: December 2021 | Updated: September 2025
References: SB 9: CA Govt. Code Sections 65852.21, 66452.6, and 66411.7, SB 684: CA Govt. Code Sections 66499.41, 65852.28, and 65913.4.5
Staff contacts: Kate Conner, kate.conner@sfgov.org and Carly Grob, carly.grob@sfgov.org
Introduction
In response to California's housing crisis, the State Legislature has introduced numerous bills to fund, incentivize, and legalize new housing. On September 16, 2021, Governor Newsom signed into law Senate Bill 9, which allows duplexes and lot splits for certain parcels in single family (RH-1) zoning districts. The bill took effect January 1, 2022. Senate Bill 450, effective January 1, 2025, amended Senate Bill 9 (together, "SB 9").
On October 11, 2023, Governor Newsom signed into law Senate Bill 684, which provides a streamlined and ministerial review path for subdivisions and the development of 10 or fewer residential units on certain parcels. This bill took effect July 1, 2024. Senate Bill 1123, effective on July 1, 2025, amended Senate Bill 684 (together, "SB 684").
A ministerial decision involves only the use of fixed standards or objective measurements, and government agencies cannot use personal, subjective judgment in deciding whether or how the project should be carried out. Notably, ministerial approvals do not require review under CEQA, or require conditional use approvals that are based on subjective factors under the Planning Code.
Demolition: Since SB 9 and SB 684 projects are processed ministerially, conditional use authorization for demolition under Planning Code Section 317 will not be required. The permit for the new units must be approved at the same time as the demolition permit for any existing structures on the property.
Noticing Requirements: Since SB 9 and SB 684 projects are processed ministerially, Neighborhood Notification under Planning Code Section 311 will not be required. The Department will not accept any requests for Discretionary Review for SB 9 and SB 684 projects.
A City agency may only deny an application for an eligible housing development under SB 9 or SB 684 if, based on a preponderance of the evidence, the agency finds that the housing development project would have a specific, adverse impact upon health and safety or the physical environment and there is no feasible method to satisfactorily mitigate or avoid the specific adverse impact.
Contents
Senate Bill 9
Senate Bill 9 (Atkins) requires ministerial approval of a housing development of two units in a single-family zone (in San Francisco, RH-1, RH-1 (D), RH-1 (S)), the subdivision of an RH-1 parcel into two parcels, or both.
Eligibility Criteria for all SB 9 Projects
- Zoning. The parcel must be located in an RH-1, RH-1(D), or RH-1(S) zoning district. To determine the parcel's zoning, consult the Planning Information Map.
- Pre-application Occupancy. The parcel must be owner-occupied or vacant for three (3) years prior to the application. A project is ineligible if the proposal includes the demolition or alteration of a housing unit occupied by tenants in the three (3) years prior to an application. Applicants will be required to provide proof of occupancy for three years prior to application, as described in the SB-9 project application forms.
- Rental Pricing Controls. Parcels are ineligible if they include existing units subject to local rent control regulations. The following are typically not subject to rental pricing controls: single family homes, condominiums, ADUs permitted under the State program, and units built after 1979. Applicants will be required to provide unit count and building construction date of any existing buildings to determine eligibility.
- Ellis Act evictions. Parcels are ineligible if they include a unit where the Ellis Act has been used in the fifteen (15) years prior to an SB 9 project application. To determine if a unit on the parcel has been subject to an Ellis Act eviction, consult with the San Francisco Rent Board.
- Historic Resources. Parcels are ineligible for SB 9 if located within a historic or landmark district under State law or if designated or listed as a landmark or historic property or district under local law (Planning Code Article 10 or 11). To determine if the parcel is designated or listed as a landmark or historic property or located in a district under local law, consult the Planning Information Map.
- Prohibition of Short-Term Rentals. SB 9 requires that the rental of any unit created under an SB 9 project be for a term longer than 30 days.
Additional Eligibility Criteria for SB 9 Lot Split Projects
- Original Parcel Size. Only parcels 2,400 square feet and larger are eligible for a ministerial lot split.
- Resulting Parcel Size. An SB 9 lot split cannot result in a parcel more than 60% or less than 40% of size of the original lot, and both newly created parcels must be at least 1,200 square feet.
- Prior Lot Splits. Any parcel established through the prior exercise of an urban lot split under SB 9 is not eligible. You may not use SB 9 to subdivide a parcel twice.
- Adjacent Lot Splits. Parcels where either the owner of the parcel, or any person acting in concert with the owner, has previously subdivided an adjacent parcel using an urban lot split under SB 9 are also not eligible.
- Post-Project Owner Occupancy. SB 9 lot split projects require the applicant sign an affidavit stating that the applicant intends to occupy one of the housing units as their principal residence for a minimum of three years from the date of the approved lot split. This requirement does not apply if the applicant is a community land trust or a qualified nonprofit corporation.
- Lot Split Easements. Projects that include a lot split may require easements for utility connections and physical access, depending on the lot split configuration. Easements must meet all applicable fire and building safety code requirements.
SB 9 Projects in San Francisco
SB 9 contains development standards and requirements that allow for a ministerial approval process and application of certain Planning Code regulations.
Objective Standards. SB 9 projects must comply with all objective requirements including zoning, subdivision, and design review standards that do not conflict with SB 9. The City cannot impose objective standards that would physically prevent the construction of up to two units or that would physically prevent either of the two units from being at least 800 square feet in floor area, except that the project must include four-foot setbacks from the side and rear lot lines outside of the buildable envelope. In most cases, the allowable building envelope in a new structure should be able to accommodate two units of 800 square feet and meet objective Planning Code requirements including rear yard, height, open space, front setbacks, side setbacks, and exposure. The San Francisco Planning Commission adopted the San Francisco Design Standards on November 14, 2024.
Accessory Dwelling Units (ADUs). ADUs allowed by State Law may be included in SB 9 projects, depending on the project scope and design and the proposed ADU type.
Non-Conforming Conditions. SB 9 prohibits the correction of nonconforming zoning conditions as a condition for ministerial approval of a lot split.
SB 9 Development Scenarios
Scenario 1: Projects without the Lot Split Provision
Without the lot split provisions, an SB 9 project could either demolish an existing single-family house and construct a new duplex, or convert the existing single-family structure into a duplex. This type of project does not require owner occupancy after project application. Neither unit would be subject to rent control, and the units could be sold as condominiums at project completion.
| Development Option | Primary Action | Resulting Structure | Additional Options |
|---|---|---|---|
| Option #1 | Demolition & New Construction | Duplex | Optional: Add a State Program ADU |
| Option #2 | Retain Original Structure | Conversion or Addition into Duplex | Optional: Add a State Program ADU |
Scenario 2: Projects utilizing the Lot Split Provision
The second path for SB 9 development is to split a single-family lot into two lots (Lot 1 and Lot 2). Both lots must be at least 1,200 sq ft, and neither can be more than 60% of the original lot size. This requires an owner-occupancy affidavit for at least three years.
| Resulting Lot | Development Option | Resulting Structure | Additional Options |
|---|---|---|---|
| Lot 1 (≥ 1,200 sq ft) | New Construction | New Duplex | Optional: Add an ADU |
| Lot 1 (≥ 1,200 sq ft) | Retain Original Structure | Conversion or Addition into Duplex | Optional: Add an ADU |
| Lot 2 (≥ 1,200 sq ft) | New Construction | New Single Family Home or Duplex | Optional: Add an ADU |
Senate Bill 684
Senate Bill 684 requires ministerial approval of eligible subdivisions and the development of 10 or fewer residential units.
Eligibility Criteria for all SB 684 Projects
Site Requirements
- Zoning. The subject parcel and development must be located on a parcel zoned multifamily residential uses, or a parcel that is vacant and zoned for single-family residential development. "Vacant" means having no permanent structure, unless the permanent structure is abandoned and uninhabitable as determined by the Department of Building Inspection.
- Location. The development must be located on a property that is not classified as prime farmland, wetlands, a high fire hazard severity zone, hazardous waste site, a delineated earthquake fault zone, a flood plain, a floodway, a community conservation plan area, a habitat for protected species, or under a conservation easement.
- Hazardous Waste Site. The development must not be located on a property that is classified as a hazardous waste site unless the project sponsor has secured a uniform closure letter for an underground storage tank or a letter from the appropriate State agency stating that the site is suitable for residential uses.
- Existing Lot. The "existing lot," or the lot proposed to be subdivided, must be no larger than five acres for multifamily uses, or one and one-half acres for vacant single-family zones; it must be surrounded on 75% of the perimeter by "urban uses"; and it cannot have been established through prior SB 684 or SB 9 lot splits.
- Demolition or Alteration of Residential Units. The project does not require the demolition or alteration of rent-controlled units, affordable units, units occupied by tenants within the preceding five years, or units subject to an Ellis Act eviction within the preceding 15 years.
Project Requirements
- Project Size. The proposed subdivision will result in 10 or fewer parcels, and the housing development project on the lot proposed to be subdivided will contain 10 or fewer units.
- Proposed Lot Requirements. The newly created parcels must be at least 600 square feet in multifamily zones (1,200 square feet in vacant single-family zones), served by public water and municipal sewer systems, and meet objective standards of the Subdivision Map Act.
- Ownership. Housing units must be constructed on fee-simple ownership lots, part of a common interest development, a housing cooperative, built on land owned by a Community Land Trust, or part of a tenancy in common.
- Density. The project must create at least one new residential unit on each resulting parcel. If identified in the City's Housing Element, it must match the projected unit count and include required affordable housing. If not in the Housing Element, it must result in at least 66% of the maximum allowable residential density.
- Average Unit Size. The average total area of floorspace for the proposed housing units does not exceed 1,750 net habitable square feet.
- Inclusionary Housing. Projects that propose 10 units must comply with the Inclusionary Housing Ordinance, Planning Code Section 415 et. seq.
- Inclusionary Housing. SB 684 projects must comply with all objective requirements including zoning, subdivision, and design review standards that do not conflict with the standards set forth in CA Govt. Code Section 66499.41 or CA Govt. Code Section 65852.28. The City cannot impose objective standards that would physically prevent the construction of an SB 684 project that complies with the requirements for density and average unit size set forth in state law, except that the project must include four-foot setbacks from the side and rear lot lines outside of the buildable envelope. Objective Planning Code requirements include rear yard, height, open space, front setbacks, side setbacks, and exposure. The San Francisco Planning Commission adopted the San Francisco Design Standards on November 14, 2024.
- Existing Dwelling Units. The proposed subdivision will not result in any existing dwelling unit being alienable separate from the title to any other existing dwelling unit on the lot.
Additional Information
Accessory Dwelling Units (ADUs): State Law ADUs may be included and do not count toward the 10-unit maximum project size.
Maximum Density: SB 684 does not provide an inherent right to construct 10 units if the underlying zoning and density calculations do not allow it, though the City cannot preclude developing at least 30 units per acre.
Minimum Density: If not in the Housing Element, the project must achieve at least 66% of the maximum permitted density. If included in the Housing Element, it must match the projected unit count up to a maximum of 10 units.
How to determine the minimum density of an SB 684 Project
- 1. Open the Housing Element Sites Inventory (Appendix B.4 on the Housing Element webpage).
- 2. Navigate to the tab titled "Table B - Submitted - Dec-22".
- Locate the project address or APN.
Hint: use the “Find and Replace” function (usually Ctrl + F)- i. If the parcel is not included on Table B, then it is not identified in the Housing Element, and the project must construct at least 66% of the maximum allowable residential density to qualify for SB 684. The maximum allowable residential density is the maximum number of units allowed by the zoning district on the subject parcel. More information on a property’s zoning can be found on the Property Information Map.
- ii. If the parcel is located on Table B, continue to the next step.
- After locating the parcel, scroll to columns AE, AF and AG for that row to determine the maximum density allowed. i. The Department will round up the number of units from any remainder 0.5 and above.
- SB 684 requires a project to provide as many low-income or very-low income units as projected in the housing element. To determine the affordable housing requirement:
- Determine which Map applies to the project (Map 1, Map 2 or Map 3).
- Find the corresponding very-low income and low-income columns for that Map. 1. Map 1: Columns E and F 2. Map 2: Columns I and J 3. Map 3: Columns M and N
- Multiply the applicable columns by the site acreage (Column R).
- Any fractional numbers will be rounded up from 0.5 and above.
For more details, you can view the full legislative history at the California Legislative Information website.