SB 9 Projects
Senate Bill 9 (SB 9) was signed into law in 2021 and became effective in 2022. The legislative intent of SB 9 is to spur additional housing development in single-family zoned residential districts. SB 9 creates a framework similar to recent State accessory dwelling unit (ADU) legislation, in that it requires ministerial approval (staff level, non-discretionary) of applications for up to four units for projects that meet minimum criteria defined by the state or local standards that further facilitate housing approvals.
SB 9 requires proposed housing developments containing no more than two primary residential units on a single parcel within a single-family residential zone to be considered for ministerial approval. SB 9 further requires a local agency to ministerially approve a parcel map for an urban lot split to create two parcels from one single-family residential parcel that meets specific requirements, resulting in the potential to build up to four primary units on existing single-family-zoned lots (up to two primary units on each of two new lots created through an urban lot split). Existing ADU laws may be combined with SB 9 regulations on lots that are not subdivided in order to provide a total of up to four units on the single-family lot (two primary units and two ADUs). SB 9’s streamlined development review and permitting process does not apply to the demolition and reconstruction of single-family dwellings.
Senate Bill 450 (SB 450) was signed into law in 2024 and became effective in 2025. SB 450 modifies and strengthens SB 9 in a number of ways and the City is in the process of preparing updates to its SB 9 Ordinance (Chapters 15.31 and 16.77 of the Municipal Code) for consistency with SB 450.
SB 9 Ordinance Update
On Monday, April 27, beginning at 7 p.m., the Planning Commission is scheduled to conduct a study session to provide feedback on potential amendments to the City’s regulations for urban lot splits and two unit housing developments, commonly referred to as “SB 9” (Chapters 15.31 and 16.77 of the Menlo Park Municipal Code). The Planning Commission will also consider options to streamline the development review process on substandard lots in single-family zones.
Study sessions provide an opportunity for Planning Commissioners and the public to provide preliminary feedback, with comments collected to inform future review and consideration of the proposal. The primary purpose of future SB 9 Ordinance amendments is to update the Municipal Code for consistency with state law, specifically Senate Bills 9 and 450 (SB 9 and SB 450). The secondary purpose of the study session is to consider potential options to streamline the development review process in single-family residential zones such as removing use permit requirements for 1) substandard lots, and 2) floor area limit (FAL) establishment for lots less than 5,000 square feet in area.
Please attend the study session to learn more about urban lot splits and two unit housing developments, single-family development requirements on substandard lots, and to share feedback on these efforts. As a study session, no formal action will be taken.
Applicability
The provisions of SB 9/SB 450 apply to the following zoning districts within the City: R-E-S, R-E, R-1-S, R-1-S (FG), R-1-U and R-1-U (LM). Prospective applicants may use the City’s GIS page to confirm the zoning of specific parcels. In addition to the requirement that an SB 9/SB 450 project be located on a single-family zoned lot, the following requirements must be met.
State objective standards for urban lot split projects
SB 9/SB 450 prescribes certain minimum development standards for urban lot split projects, while giving cities the flexibility to impose their own objective design standards. The following standards are mandated by the state law and are applicable to all jurisdictions.
| Standard |
Explanation |
| Lot area |
In the event of an urban lot split, each resulting lot must be a minimum of 1,200 square feet in size, with neither of the new lots being less than 40% the size of the original lot. |
| Subsequent lot split projects |
An applicant may not apply for the subdivision of a property that was itself created by an urban lot split. Additionally, a single applicant or multiple applicants working together may not use the provisions of SB 9 to split adjacent lots. |
| Rental period |
If a unit created by an SB 9 project is intended to be placed on the rental market, the minimum rental term is 30 days. Therefore, the units may not be used as short-term rentals (such as Airbnb). |
| Owner occupancy |
The applicant of an urban lot split project will be required to sign an affidavit stating that they will occupy one of the units as their primary residence for a minimum of three years from the date of the lot split. |
| Construction/demolition allowances |
If an existing residence is subjet to covenants and restrictions limiting rental prices to residents with moderate, low or very low income (BMR units) or has been occupied by a tenant within the last three years, the unit may not be completely demolished. |
Process for SB 9 projects
Review of urban lot splits and two-unit development projects will be processed ministerially. A building permit will be required for the construction of new units and subdivisions will be processed by the Engineering Division. However, it is recommended you speak to a planner before submitting applications.
Building permit applications are required to be submitted online through the online permit portal. Instructions on how to submit a building permit application may be found on the building permit application submittal guidance webpage. The process and required materials for urban lot split applications was approved by City Council at the March 28, 2023 meeting. Please refer to Chapter 15.31 of the Menlo Park Municipal Code for guidance on urban lot split applications. It is recommended you speak to an engineer before submitting an application for an urban lot split. The parcel map checklist for urban lot splits and grading and drainage guidelines can be found in the related documents below.
Related documents
Planning
Building
Engineering