Urban Lot Splits & Two-Unit Developments in Single-Family Zones

Background	Implementation
What is a Two-Unit Development?	Summary of Process for Adding a Second Primary Dwelling Without an Urban Lot Split
What is an Urban Lot Split?	Summary of the Process for an Urban Lot Split
Additional Resources

Background:

Effective January 1, 2022, California law allows property owners in single-family zoning districts (R-1 and R-BA districts) to do the following, subject to meeting defined eligibility criteria:

Urban Lot Splits: Property owners in the R-1 district and R-BA district may split one property they own, one time, into two developable lots without discretionary review (i.e., reviewed by City staff, not the Planning Commission). There are many eligibility criteria that apply and not all lots will be eligible for an urban lot split. Properties in the R-BA District specifically may be ineligible depending on environmental/habitat and infrastructure constraints.
Two-unit Developments: Property owners in the R-1 and R-BA districts may establish two-unit developments (duplexes) on their properties. Eligibility criteria includes considerations for tenant-occupied housing as well as whether the property adjoins a public street and has access to all utility infrastructure required by the Municipal Code.

Implementation:

The City of Brisbane is currently drafting an implementing ordinance which is anticipated to be adopted by the end of this year. In the meantime, the City will process applications for urban lot splits and two-unit developments under the statute's provisions and current R-1 and R-BA district regulations.

What is a Two-Unit Development?

A two-unit development project allows owners of properties in the R-1 and R-BA Districts to establish up to two primary dwellings on a single residential property, whether the proposal adds up to two new dwellings or adds one new dwelling to one existing dwelling. This can be combined with the ministerial urban lot split. Accessory dwelling units (ADUs) and junior ADU (JADUs) are permitted in accordance with Brisbane Municipal Code (BMC) Chapter 17.43 when there is not an urban lot split. The following applies:

One parking space is required per primary dwelling unit;
Not allowed to demolish more than 25% of existing exterior walls if property has been occupied by a tenant within the last three years;
Development would not be allowed to demolish or alter existing homes rented within the last three years, rent controlled housing, or deed restricted affordable housing;
Short-term rentals (STRs) are prohibited in new units (as well as ADUs and JADUs); and
Where a proposed new dwelling is located closer than five (5) feet to a property line or other structure, both proposed AND existing structures will need to comply with design criteria for fire-rating and limitations on wall-openings.

Summary of Process for Establishing a Two-Unit Development Without an Urban Lot Split:

To establish a two-unit development without an urban lot split, a Building Permit application and SB 9 Qualifying Criteria Checklist is required. All building permit applications must be filed online.

What is an Urban Lot Split?

An Urban Lot Split is a one-time subdivision of an existing single-family residential parcel into two parcels. Up to two units (including ADUs or JADUs) are allowed on each newly created parcel. The urban lot split must:

Comply with Subdivision Ordinance and Subdivision Map Act standards unless it would conflict with State law;
Propose two lots that are roughly proportional in size (smallest lot must be at least 40% of the existing lot size) that are each at least 1,200 sq ft;
Each lot created must adjoin a public right-of-way;
Owner must occupy one of the units of the resulting lots;
- Please note that urban lot splits require a deed restriction and/or affidavit in order to comply with State law requirements;
Parcel map shall be prepared by a licensed professional; and
Urban lot split may allow the sale of excess land for the construction of new housing.

Note, STRs are prohibited in duplexes, ADUs, and JADUs.

Summary of the Process for an Urban Lot Split:

Until the City adopts an implementation ordinance, urban lot splits will be processed according to the procedures listed below. Please consult with planning staff if you have questions and before submitting an application to determine whether a ministerial parcel map or lot line adjustment are appropriate given the circumstances. (We will need addresses and/or APNs for this consultation.)

An application for either a ministerial parcel map or lot line adjustment is required. For an urban lot split that requires a parcel map, a singular application is required (standard parcel maps require an initial tentative and subsequent final parcel map applications), meaning the parcel map included must contain all the required components of both a tentative and final parcel map outlined in the BMC and listed within the individual checklists linked below. Depending on the context, many elements required for a standard tentative parcel map may be waived by staff. These requirements can be addressed in a pre-application consultation.

Lot Line Adjustment checklist; see line P43 of the Master Fee Schedule for fee

Tentative Parcel Map checklist; see line P35 of the Master Fee Schedule for fee

Final Parcel Map checklist; fee n/a

The application (either lot line adjustment or parcel map) will be processed ministerially by staff, as required by the statute. No public hearings are required.