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Development Services

This Information Bulletin addresses the City of San Diego’s regulations to implement California Senate Bill 9 (SB 9), which permits multi-dwelling unit development and lot splits, under specified circumstances, on parcels zoned for single-dwelling unit development and Planned District Zones that permit single dwelling unit development.

This bulletin provides guidance on requirements for obtaining a building permit to construct a dwelling unit using those provisions. The development of the housing units is referred to as Multi-Dwelling Unit Development (MDUD), and the relevant provisions are contained in Section 143.1310 of the San Diego Municipal Code (SDMC). This bulletin also provides guidance on requirements for obtaining a parcel map to perform a lot split using those provisions. The mapping action is referred to as an “Urban Lot Split” (ULS) and the relevant provisions are contained in Section 143.1315 of the SDMC. An applicant may utilize the MDUD provisions or the ULS provisions or a combination of both.


  1. A MDUD is a development resulting in no more than two dwelling units on a single lot, inclusive of new and existing structures.
  2. An Urban Lot Split (ULS) is an action that divides an existing single premise into no more than two separately conveyable lots.

Regulations that Apply to both MDUDs and ULS Projects

  1. Permitted Zones
    An MDUD/ULS is permitted on a lot zoned for single-dwelling unit development but not multiple-dwelling unit development. Specifically, it is allowed in zones where the Use Regulation Tables identify an MDUD allowed as a Limited Use: RS, RE, RX, and RT zones and Planned District Zones that permit single dwelling unit development but not multiple dwelling unit development.
  1. Base Zone Designations: Use Regulations Tables in SDMC Chapter 13, Article 1, Divisions 1 through 7
  2. Planned District Ordinance Zone Designations: Use Regulation Tables in SDMC Chapter 15, Articles 2 through 20
  3. Find your zone designation:
  1. Zoning and Parcel Information Portal (ZAPP)
  2. Zoning Address Look-Up
  1. Eligibility Requirements
    MDUDs/ULSs are not permissible on certain premises as specified by §143.1303(b). For example, they are not allowed if any portion of the parcel is located in or contains any of the following:
  1. Prime farmland or farmland of statewide importance;
  2. Wetlands;
  3. The Very High Fire Hazard Severity Zones, unless the development complies with Chapter 7A of the California Building Code;
  4. A hazardous waste site, unless the site has been cleared for residential or mixed uses;
  5. Special Fire Hazard Areas, unless the premises have been subject to a Letter of Map Revision prepared by the Federal Emergency Management Agency (FEMA) and issued to the local jurisdiction or the premises meet the FEMA requirements necessary to meet minimum flood plain management criteria of the National Flood Insurance Program;
  6. A delineated earthquake fault zone, unless the development complies with applicable seismic protection building code standards;
  7. A regulatory floodway as determined by FEMA;
  8. The Multi-Habitat Planning Area (MHPA) of the Multiple Species Conservation Program (MSCP) Subarea Plan;
  9. Environmentally Sensitive Lands conserved by dedication, a covenant of easement, or conservation easement;
  10. A historic district that is a designated historical resource or on a property containing a designated historical resource;
  11. A development that requires demolition or alteration of a dwelling unit that contains rent-controlled housing or a dwelling that a tenant has occupied in the last three years
  12. A development that requires the demolition or alteration of a dwelling unit that is subject to a recorded covenant, ordinance, or law that restricts rents to levels affordable to persons and families of moderate income, low income, or very low income;
  13. Premises with SRO hotel rooms/dwelling units that were withdrawn from rent or lease in accordance with California Government Code Sections 7060 through 7060.7 during the 15 years preceding the applications or
  14. A development that requires the demolition of more than 25% of the existing exterior structural walls of a dwelling unit that a tenant has not occupied in the last three years.
  1. Floor Area Ratio (FAR): Development that involves an Urban Lot Split and construction of an MDUD shall comply with the FAR of the underlying zone unless the second dwelling unit results in the lot exceeding the FAR in the underlying zone. The second unit in this instance, is limited to 800 square feet.
  2. Coastal Development Permit (CDP) Required: Properties in the Coastal Overlay Zone are subject to the Coastal Development procedures within SDMC Section 127.0704 in Chapter 12, Article 6, Division 7. A CDP is required for all MDUD and/or Urban Lot Split applications within the Coastal Overlay Zone.
  3. An application for an MDUD or ULS may be denied if the City determines that the development would have an adverse impact on public health and safety or the physical environment.

Additional Information for MDUDs

  1. Permit Application Process and Submittal Documents
    1. Building Permit Required: A building permit is required to construct an MDUD (Process One).
    2. Submittal Document Requirements for MDUDs (R3 Occupancy Classifications): Project Submittal Manual Section 2A.
      1. Minimum plans/calculations submittal requirements include the following:
        • Site plan and vicinity map
        • Floor plans and roof plans
        • Elevations and sections (as applicable)
        • Structural plans and details
        • Structural calculations and/or trust calculations (as applicable)
        • Title 24 Energy calculations
      2. Forms:
  • General Application, DS0-3032
  • Declaration: Eligibility and Acknowledgement of Restrictions Related to Senate Bill 9, DS-3063
  • Water Meter Data Card, DS-16
  • Storm Water Applicability Checklist, DS-560
  1. How to Apply
    Applications for multi-family dwellings are being accepted in paperless digital formats:
  1. Digital Application Portal can be navigated here: Development Services Application Portal
  1. For new Permit Applications, request “Building Permit.”
  2. For changes to an existing issued permit (under construction), request “Construction Change to a Building Permit.”
  1. Other Development and Zoning Standards
  1. Unit Size: If a dwelling unit already exists on the lot, the second primary dwelling unit can be no larger than 800 square feet if the parcel is non-compliant with development regulations such as the FAR in the underlying zone. The development shall otherwise comply with the development regulations in the underlying zone.
  2. Rental information: An MDUD shall not be rented for fewer than 31 days.
  1. Parking
  1. No off-street parking is required if the unit is proposed within a Transit Priority Area (TPA).
  2. For parcels outside of a TPA, one off-street parking space per dwelling unit is required for the third and fourth units (of any kind) constructed on the initial (unsubdivided) lot.
  3. One off-street parking space per dwelling unit is required within the Beach Impact Area of the Parking Overlay Zone unless the applicant can demonstrate to the satisfaction of the City Manager that there is access to a car share or other shared vehicle within one block of the premises.
  1. Setbacks
  1. No setback is required for a conversion of an existing structure to a new dwelling unit;
  2. A dwelling unit constructed in the same location or within the building envelope as an existing structure may observe the same setbacks;
  3. Newly constructed dwelling units must comply with street side yard and front yard setbacks of the underlying zone;
  4. Newly constructed one-story dwelling units with a 16-feet height or less may abut the interior side or rear property line;
  5. Newly constructed dwelling units exceeding 16 feet in height shall have a four-foot interior or rear setback if abutting a residential zone or a premise developed with exclusively residential uses.
  1. Landscaping:
  1. Two trees are required on the premises for every 5,000 square feet of lot area (minimum of one tree per lot);
  2. If proposing more than two dwelling units across two lot, compliance with street tree regulations in Section 142.0409 is required.
  1. Parcels in Areas of Future Sea Level Rise in the Coastal Overlay Zone: The recorded owner of the dwelling unit shall enter into an agreement with the city demonstrating compliance with regulations regarding future sea level rise based on the most current sea level rise vulnerability maps.
  1. Fees:
  1. For a complete list of fees that may apply, reference Information Bulletin 501.
  2. For information about specific fees, please note that MDUDs are subject to payment of School Fees, Development Impact Fees, and the Regional Transportation Congestion Improvement Program Fees (RTCIP)

Additional Information for Urban Lot Splits

  1. Permit Application Process and Submittal Documents
  1. Shall be permitted in accordance with a Process One (ministerial) Parcel Map and shall comply with Chapter 14, Article 4, Division 3 of the SDMC:
    1. Public rights-of-way, offsite improvements and the correction of nonconforming zoning conditions are not required. However, Americans with Disabilities Act (ADA), accessibility, pedestrian, and vehicular access, alley, utility service and other improvements may be required.
    2. Development Plan Package will be required as part of the Parcel Map application, as described in the Land Development Manual, Project Submittal Requirements, Section 5, Subdivision Approvals, Item No. 13.0 of the Submittal Requirements Matrix.
  1. Prior to the recording of the urban lot split, the record owner shall sign Form DS-3062, an affidavit acknowledging that the record owner intends to reside in one of the dwelling units as their primary residence for a minimum of three years from the date of approval. The document shall be signed by the City and recorded in the Office of the County Recorder. Form DS-3063 will also be required.
    1. This requirement does not apply if the record owner is a community land trust or a nonprofit corporation as specified by the law.
  1. How to Apply:
    Applicants for multi-unit dwellings are being accepted in digital paperless formats:
    1. Digital Application Portal can be navigated here: Development Services Application Portal;
    2. For new Permit Applications, request “Parcel Map.”
  2. Improvements or modifications required for the subdivision to comply with the ULS regulations must be ensured or completed before the recordation of the Parcel Map. These improvements or modifications may include the right of way, water, sewer, stormwater, fire suppression or other issues.
  1. Restrictions on Urban Lot Splits
    1. In addition to the restrictions above, Urban Lot Split provisions may not be used in the following circumstances:
      1. The lot is not located in a single-family zone;
      2. The lot was established through a prior Urban Lot Split; or
      3. The recorded owner or any person acting with the recorded owner has previously subdivided an adjacent lot.
  1. Parcels created through urban lot splits must comply with all of the following:
    1. The development regulations of the base zone where the lot is located shall apply, except as specified in SDMC Chapter 14, Article 3, Division 13;
    2. The two lots shall be approximately equal in size, with either lot not being smaller than 40 percent of the lot area of the original lot;
    3. The newly created lots shall not be smaller than 1,200 square feet;
    4. Any lots created shall be split in a manner that complies with the floor area ratio (FAR), street frontage, driveway width requirements and other standards in the underlying zone, whenever feasible:
  • Developments that do not comply with street frontage and driveway width requirements of the base zone shall record an access easement on the lot.
  1. Other limitations:
    Any rental unit created through an urban lot split shall not be rented for less than 31 days. In addition, only residential uses are permitted on a lot created by an urban lot split.
  1. Number of Dwelling Units
    The regulations allow no more than two MDUDs, whether existing or new, on a lot. Under certain circumstances, an applicant may also use these regulations in conjunction with the Accessory Dwelling Unit regulations. However, under no circumstances shall the total number of dwelling units across the two lots result in more than four units. For example:
    1. No Urban Lot Split: A property would allow up to two MDUD units, subject to applicable regulations, and would allow up to two ADUs or JADUs; under no circumstances shall the total number of dwelling units result in more than four units. Constructing accessory units in this manner may restrict future development. See Section V. for further information.
    2. Urban Lot Split: If the project proposes a lot split using the ULS provisions and construction of MDUD units, then no ADUs/JADUs would be permitted. The project may propose up to two MDUDs on each lot resulting from the subdivision for a total of no more than four on the initial (unsubdivided) lot.
  1. Fees
    For a list of fees that may apply to ULSs, reference Information Bulletin 502

Order of Processing of MDUDs and Urban Lot Splits

Applicants considering Urban Lot Splits and MDUDs should carefully weigh the options and take timing into account. Whenever possible, applicants should apply for the Urban Lot Split and the MDUD concurrently. There may be substantial implications to obtaining an Urban Lot Split approval first and applying for a building permit for the MDUD later, or doing the reverse, depending on the specific project.

As one example, building an MDUD first may mean that, upon applying for an Urban Lot Split later, the applicant has placed the building in a location that prevents compliance with basic subdivision requirements and subsequently, the applicant’s request for an Urban Lot Split may not be approved. Similarly, performing an Urban Lot Split first may mean that, upon applying for a building permit later for a second dwelling unit, the applicant has not placed the lot line in a manner that allows for the structure’s conformance with the SDMC.

Providing a project application that includes both the mapping and building request will reduce the likelihood of unintended consequences such as these. Thus, an applicant may, subject to the risks described above:

  • Propose unit(s) only. This could mean a second unit on a lot with one unit or two units on a vacant lot.
  • Propose an Urban Lot Split only. This will require a basic development package that sufficiently describes the unit to be proposed on the site, with enough detail to provide the reviewers the information they need (e.g., about the location for the building footprint and square footage) to make the determinations regarding SDMC compliance.
  • Propose units and an Urban Lot Split concurrently (preferred option).  

Also, note that mixing MDUD and ADU/JADU units on a lot may impact eligibility for future development. For example, an applicant electing to construct two MDUDs and two ADUs may, upon a later application for a subdivision, find that the project is ineligible.

Applicants should consider these factors, perhaps in consultation with their architects and contractors, before submitting a project application. Applicants may also discuss the options with City staff using available tools such as Preliminary Review and Virtual Counter.