California’s Senate Bill 9 (SB 9) went into effect on January 1, 2022. It allows homeowners in single-family zones to split their lot and add housing — with ministerial approval and no public hearing. That’s a significant change in a city where zoning has historically been one of the most protective in the state.
Here’s what the law actually allows in Manhattan Beach, how the process works, and what it means for homeowners and buyers who are thinking through their options.
What SB 9 Allows
SB 9 has two components that can be used independently or together:
1. Urban Lot Split
A homeowner can split a single parcel into two separate lots. Each new parcel must be at least 1,200 square feet and at least 40% of the original parcel’s size. The split must result in two roughly equal parcels — one cannot be more than 60/40 relative to the other.
2. SB 9 Duplex
On any RS-zoned lot — split or not — a homeowner can build a duplex (two units on one parcel) by right, replacing or adding to an existing single-family home.
Combined: Up to 4 Units on One Original Lot
If you do both — split the lot and build a duplex on each new parcel — you can end up with up to 4 units on what was originally a single-family parcel. All approvals are ministerial, meaning the city cannot hold a hearing or apply discretionary judgment to deny a compliant application.
How It Works in Manhattan Beach
Manhattan Beach applies SB 9 to RS-zoned (single-family residential) parcels only. The approval process is ministerial — if your project meets the state and local code requirements, the city is obligated to approve it without a public hearing or Planning Commission review.
The base application fee is $572.
Key requirements under state law and local implementation:
- Owner-occupancy — to use the lot split, you must have lived on the property as your primary residence for at least 3 of the past 5 years. This requirement does not apply to the SB 9 duplex without a lot split.
- No tenant displacement — you cannot use SB 9 to displace current tenants. If the property has been rented in the past 3 years, additional restrictions apply.
- Setbacks — SB 9 units must comply with standard RS-zone setbacks, except that a 4-foot rear and side setback applies to units that are built entirely new. Existing structures converted to a new unit must meet existing nonconforming setbacks.
- Height limits apply — SB 9 does not override Manhattan Beach’s height limits. In the Tree Section and Hill Section, that’s 26 feet / 2 stories. In the Sand Section, 30 feet / 3 stories.
- No short-term rentals — SB 9 units cannot be used as short-term vacation rentals. They must be rented long-term or owner-occupied.
- Coastal Zone — SB 9 applicability in the Coastal Zone is pending California Coastal Commission (CCC) certification. Homeowners in the Sand Section west of Highland Ave should confirm current status with the Planning Division before proceeding.
What SB 9 Actually Looks Like in Manhattan Beach
The most realistic use case in Manhattan Beach is not a homeowner tearing down a $4M single-family home to build four rental units. It’s much more nuanced than that.
The properties where SB 9 creates the most interesting options are larger RS-zoned lots — primarily in the Hill Section and Mira Costa, where lot sizes can range from 5,000 to 7,500 square feet or more. On a standard Sand Section lot (~2,700 sq ft), splitting into two parcels of 1,200+ sq ft each leaves very little buildable area on each parcel.
More practically, SB 9 is relevant to:
- Homeowners considering a detached second unit who want the option to eventually sell the second parcel independently
- Buyers evaluating larger lots where future flexibility to split has real long-term value
- Move-up buyers who want to keep a property as income-producing while they purchase elsewhere, without triggering the STVR restrictions
SB 9 vs. ADUs: Which Makes More Sense?
For most Manhattan Beach homeowners, an ADU (accessory dwelling unit) is a simpler path to adding a unit and generating rental income. ADUs don’t require owner-occupancy, can be attached or detached, and have a well-established approval process in Manhattan Beach.
SB 9 becomes more relevant when the goal is to eventually hold or sell a second parcel independently — or when a homeowner has a lot large enough that two buildable parcels each make sense on their own. If you’re adding one rental unit for income, the ADU route is usually faster and less complex. If you’re thinking about the long-term disposition of a larger parcel, SB 9 is worth a conversation with a planning consultant.
For more on ADUs: ADU Guide for Manhattan Beach.
How to Find Out If Your Lot Qualifies
The fastest way to check SB 9 eligibility for a specific parcel in Manhattan Beach:
- Confirm RS zoning — use the city’s Interactive GIS Map or call Planning at (310) 802-5520
- Check your lot dimensions and square footage — the lot must produce two parcels of at least 1,200 sq ft each at a 40/60 minimum split
- Verify Coastal Zone status if you’re in the Sand Section
- Consult with the Planning Division — the city offers pre-application meetings that can confirm feasibility before you pay any fees
Important: State and local regulations evolve, and SB 9 implementation can vary by parcel. Before starting an application, verify current requirements directly with Manhattan Beach Planning at (310) 802-5520. This guide is informational — the city has final say on what’s allowed for your specific property.
If you’re evaluating a property and want to think through what SB 9 could mean for a specific address, I’m happy to walk through it — particularly if lot size and future flexibility are part of what you’re weighing.
Cecilia Agraz | Stroyke Properties Group
310-803-9338 | cecilia@manhattanhermosahomes.com
DRE #01974999
Also reading: ADU Guide for Manhattan Beach | New Construction in Manhattan Beach | Manhattan Beach for Real Estate Investors
Cecilia Agraz
South Bay neighbor and Realtor® focused on clear guidance and low‑stress moves in Manhattan Beach & Hermosa Beach.