SB9 allows lot splitting in single-family zones with only ministerial review
California Senate Bill 9 (SB9) allows a property owner – if certain conditions are met – to subdivide a parcel in a single-family zone into two lots that can be smaller than the required minimum size (usually 7,500 square feet). SB9 is meant to help ease the state’s critical shortage of affordable housing by encouraging the building of smaller houses on small lots to increase the supply of less expensive, starter homes.
SB9 requires that municipalities apply only ministerial review to applications. This means that projects can’t be denied by local design review boards, planning commissions, county supervisors, or city officials if they meet certain criteria, nor do they have to comply with the California Environmental Quality Act. However, they must comply with basic health and safety requirements and environmental laws as overseen by agencies such as public works and fire departments.
Benefits of lot-splitting
Financial. Homeowners can optimize their property’s potential by selling the newly created lot or building long-term rental units to generate stable passive income. Owner occupancy is required because SB9 was not intended to allow developers to buy up lots and split them.
Family. Homeowners who have elderly parents or young adult children may wish to build units for multi-generational living.
Hurdles to splitting a residential lot
Cost. Most municipalities require application fees and recording of a parcel map, among other things. Professional reports may also be required. Costs can range from a few hundred to several thousand dollars, depending on your municipality’s requirements.
Lender approval. If you have a mortgage, your lender must approve a lot-split.
Paperwork. Regardless of jurisdiction (we discuss varying requirements below), all SB 9 urban lot split applications must be accompanied by these documents:
- Preliminary Parcel Map (prepared by a surveyor or civil engineer)
- Certificate of Occupancy
- Owner Occupancy Affidavit
Depending on your jurisdiction (city, town, or county) and property characteristics, you may also need to include one or more of the following:
- Certified Tree Report
- Soils Report
- Photos of the property
- Land Records Map
- Grant Deeds
- Habitat Statement Form
- SB 9 Urban Lot Split Checklist
Conditions for splitting a lot
State rules governing lot splits are numerous and complex. The key requirements are:
- Single family lots must be in a residential zone.
- Located in an urbanized area or “urban cluster.”
- Lots must front a public right of way. A lot may not qualify it it has access only from a private street or driveway.
- Not in a state/local historic district and not a historic landmark
- Lot must be split roughly in half – smaller lot at least 40% of the original lot.
- Each new lot should be at least 1,200 sq. ft.
- Lot is not adjacent to another lot split by SB 9 by the same owner or “any person acting in concert with the owner.”
- Lot was not created by a previous SB 9 split.
- Applicants must sign an affidavit stating they intend to live in one of the units for 3+ years after approval.
- Short-term rentals of less than 30 days are not allowed.
A lot cannot be split if it is in one of these categories:
- Prime farmland or farmland of statewide importance.
- Wetlands.
- Identified for conservation or under conservation easement.
- Habitat for protected species.
- Within a very high fire hazard safety zone.
- Contains a hazardous waste site.
- Within a delineated earthquake fault zone .
- Within a 100-year floodplain or floodway.
- The lot-split alter or demolish deed-restricted affordable housing or rent-controlled housing.
Additional requirements for lot splits in Marin county
SB9 allows local agencies to impose additional requirements for lot splits, so it is important to identify the jurisdiction in which your property is located.
Marin is comprised of 11 incorporated towns and cities, but many people do not realize there is also 450 square miles of unincorporated area (about half of Marin) under the jurisdiction of the County of Marin. These unincorporated areas include Greenbrae, Kentfield, Bel Marin Keys, and Lucas Valley and many others, plus neighborhoods considered to be in Mill Valley but outside city limits (Almonte, Alto, Homestead Valley, Tamalpais Valley, Strawberry Manor, Harbor Point, and Panoramic/Muir Park.)
The county, which administers unincorporated areas, and the 11 cities may have different rules, including requirements for easements for public services and facilities and access to a public right of way. For information about the rules that pertain to your property – including the number of supplemental units (ADUs and JDUs) allowed, how to file an SB9 application, and fees, contact your local planning department.
To find the appropriate jurisdiction for your property, consult this map provided by Marin LAFCo or MarinMap. If you use MarinMap, you can “Search by Address” to find a great deal of information about a property, including the responsible jurisdiction.