Land Development, Lot Splits and Entitlements in the North Bay
Land development in the North Bay now runs on two tracks: the traditional local track of zoning, subdivision maps and use permits, and a set of state laws (SB 9, SB 684 and SB 1123, the ADU statutes, the builder’s remedy and SB 79) that can override parts of local zoning when a site qualifies. Which track applies depends on the parcel’s zoning, whether it sits in a city or unincorporated county land, its hazard mapping and who lives there now. This page compares the state laws side by side and points to our detailed guide for each.
The practical question for an owner or buyer is rarely “what does the law allow in general?” It is “what can this parcel get approved, on what timeline, and with how much discretion left to the city or county?” The table and sections below are written to answer that, parcel by parcel, before money changes hands.
State housing laws compared
This summary reflects the statutes and agency guidance we reviewed in October 2026. Each law has more conditions than fit in a table, so treat a “yes” here as a reason to check, not as an approval.
| Law | What it allows | Where it applies | Key limits | Status (October 2026) |
|---|---|---|---|---|
| SB 9 (Gov. Code 65852.21 and 66411.7) | Two primary homes on one lot, a split of one lot into two, or both | Single-family zones in a city whose boundaries include part of a U.S. Census urbanized area or urban cluster, or, in unincorporated areas, on a parcel wholly inside one | Excluded sites (historic, prime farmland, wetlands, certain fire, flood and fault zones unless conditions are met), no demolition of tenant-occupied or rent-controlled housing, 3-year owner-occupancy affidavit for splits, no more than two units per lot after a split | In effect since January 1, 2022; amended by SB 450 (Chapter 286, Statutes of 2024), which added a 60-day decision deadline |
| SB 684 and SB 1123 (Starter Home Revitalization Act) | Up to 10 lots and 10 homes on one site, approved ministerially | Multifamily-zoned lots of 5 acres or less; since SB 1123, vacant single-family lots of 1.5 acres or less | Average home size no more than 1,750 net square feet; Very High fire hazard zones, and High or Very High zones in State Responsibility Areas, excluded with limited exceptions, along with farmland and wetlands; no displacement of tenant-occupied or rent-controlled housing | SB 684 took effect July 1, 2024; SB 1123’s single-family provisions took effect July 1, 2025 |
| ADU and JADU law (Gov. Code 66310 to 66342) | Accessory dwelling units and junior ADUs on single-family and multifamily lots | Statewide, with local ordinances that must conform to state law | JADUs up to 500 square feet inside a single-family home; local caps can’t fall below 850 square feet (1,000 for more than one bedroom); owner occupancy can’t be required for ADUs | Renumbered by SB 477 (Chapter 7, Statutes of 2024); applications must be decided within 60 days or are deemed approved |
| Builder’s remedy (Housing Accountability Act, Gov. Code 65589.5) | A housing project that doesn’t match local zoning or the general plan | Only in a city or county without a housing element that HCD or a court has found in substantial compliance | Mixed-income projects need 13% lower-income, 10% very low-income or 7% extremely low-income units; density caps apply | Revised by AB 1893 and AB 1886, in effect since January 1, 2025 |
| SB 79 (transit-oriented development) | Taller, denser housing within a half mile of qualifying rail and bus rapid transit stops | Urban transit counties; in the Bay Area, ABAG lists San Francisco, Alameda, San Mateo and Santa Clara | Not in unincorporated areas until the seventh housing element cycle; height and density depend on tier and distance | Signed October 10, 2025; applies from July 1, 2026 |
Two things the table can’t show: local implementation and timing. Cities and counties adopt their own forms, fees and objective standards, and a state law that applies on paper can still stall on utilities, access or a hazard finding.
SB 9: two homes or two lots on a single-family parcel
SB 9 lets an owner build up to two primary homes on a lot in a single-family zone, split that lot into two, or do both. Approval is ministerial, which means no public hearing, and the city or county may apply only objective standards that don’t physically preclude two units of at least 800 square feet each.
In unincorporated Sonoma County, Permit Sonoma treats R1, RR and AR as the single-family zones for SB 9 and processes a split as a minor subdivision. Santa Rosa, Petaluma and unincorporated Marin each publish their own SB 9 guidance. Our SB 9 lot split guide for Sonoma, Napa and Marin walks through the exclusions, the owner-occupancy affidavit and each jurisdiction’s process.
SB 684 and SB 1123: small-lot subdivisions of up to 10 homes
The Starter Home Revitalization Act lets a qualifying site be divided into as many as 10 lots with 10 homes, approved within 60 days or deemed approved. HCD’s April 2026 fact sheet describes eligible sites as urban lots under five acres zoned for multifamily use, in incorporated cities or large urban counties.
SB 1123 extended the law to vacant single-family lots of up to 1.5 acres that are surrounded by substantially urban uses. “Vacant” is defined narrowly: no permanent habitable structure and no occupancy in the past five years.
On those single-family sites, each new lot must be at least 1,200 square feet. Read our SB 684 and SB 1123 small-lot subdivision guide before pricing a lot on this basis.
ADUs, JADUs and adding units to apartments
The ADU statutes are the most widely used of these laws because they reach almost every residential lot. A city or county must act on a complete ADU application within 60 days, and ADUs of 750 square feet or less are exempt from impact fees.
Apartment owners have their own rules: on a lot with an existing multifamily building, state law allows up to eight detached ADUs, but not more than the number of existing units. Our multifamily ADU guide covers that path, and our ADU investment guide covers costs, rents and financing. For rural lots in Sonoma County, see land, building lots and ADUs in Sonoma County.
The builder’s remedy and SB 79
The builder’s remedy is a penalty on jurisdictions, not a right attached to land. It applies only where the city or county lacks a housing element that HCD or a court has found in substantial compliance, and since AB 1886 a jurisdiction can’t certify itself. Compliance is measured when the developer files an SB 330 preliminary application, which is why timing matters.
Check a jurisdiction’s status on HCD’s Housing Element Review and Compliance Report on the day you file, not from an old news story. Our builder’s remedy guide explains the affordability options, density limits and vesting.
SB 79 raises allowed height and density near qualifying transit stops in urban transit counties. ABAG’s July 2026 summary lists San Francisco, Alameda, San Mateo and Santa Clara as the eligible Bay Area counties, so Sonoma, Napa and Marin aren’t on that list and SMART stations aren’t covered. The details, including the tier table, are in our SB 79 transit upzoning guide.
The traditional local track: maps, zoning and permits
Most North Bay land, especially rural and agricultural parcels, still moves through the conventional process. Under Permit Sonoma’s definitions, a minor subdivision divides land into four or fewer parcels through a tentative parcel map, and a major subdivision creates five or more. Both follow the Subdivision Map Act and the county’s subdivision and zoning codes.
That track brings discretionary review, CEQA analysis where required, and conditions such as road improvements and water and septic proof. Our guide to subdividing land in Sonoma and Napa covers minimum lot sizes and agricultural limits, and our land entitlement process guide covers rezoning, use permits and CEQA step by step.
How to screen a parcel before you buy or sell
- Confirm the jurisdiction. A city address doesn’t mean a city parcel. Confirm whether the city, Permit Sonoma, Napa County Planning, Building and Environmental Services, or the Marin County Community Development Agency has authority.
- Pull the zoning and general plan designation. SB 9 needs a single-family zone, SB 684 a multifamily zone or a vacant single-family lot, and split-zoned parcels have their own rules.
- Check the hazard maps. The State Fire Marshal’s map for State Responsibility Areas took effect April 1, 2024, and local-area maps were released in four phases between February and March 2025. Several state laws exclude Very High Fire Hazard Severity Zones, and SB 684 also excludes High zones on the State Responsibility Area map; see our North Bay fire hazard severity zone guide.
- Ask who has lived there. SB 9 and SB 684 both bar projects that would demolish or alter tenant-occupied or rent-controlled housing within set look-back periods.
- Test utilities and access. Sewer and water capacity, a will-serve letter or well and septic feasibility, and legal road access decide more projects than zoning does.
- Get a preliminary read from staff. Permit Sonoma offers planner office hours, but its preliminary determinations aren’t binding, so build the answer into your contingency period.
For acreage in Napa County, start with our Napa County land guide, since agricultural zoning there limits most of these tools.
Questions people ask
Does SB 9 apply to rural land in Sonoma County?
Only if the parcel is in a single-family zone and wholly inside a U.S. Census urbanized area or urban cluster, the test for unincorporated land. Permit Sonoma counts R1, RR and AR as single-family zones, but many rural parcels fall outside the Census urban boundary, so check the county’s eligibility map and checklist first.
Can I use SB 9 and ADU law on the same lot?
Without a lot split, yes: two primary homes plus ADUs and JADUs under local rules. After an SB 9 split, a city or county doesn’t have to allow more than two units on each new lot, counting ADUs and JADUs.
Does SB 79 upzone land near SMART stations?
Not under ABAG’s July 2026 summary, which lists only San Francisco, Alameda, San Mateo and Santa Clara as the Bay Area’s eligible urban transit counties. Sonoma and Marin aren’t on that list.
How do I know if the builder’s remedy is available in a city?
Check HCD’s Housing Element Review and Compliance Report for that jurisdiction. Since 2025 a city is in compliance only once HCD or a court has said so, and status is measured when the preliminary application is filed.
Are these approvals subject to CEQA?
Ministerial approvals under SB 9 and the Starter Home Revitalization Act aren’t subject to CEQA review. Traditional subdivisions, rezonings and use permits generally are, which is one reason they take longer.
Does a parcel’s development potential raise its value?
Only to the extent a buyer believes it can be approved, built and financed. An appraiser or buyer will discount potential that depends on a rezoning, an unresolved hazard or missing utilities.
If you’re weighing a lot split, a small-lot subdivision or a sale to a builder, we can pull the parcel’s zoning, hazard and utility records and price it on what can actually be approved. Request a valuation of your land or start from our investment property services.
This is general information, not legal or tax advice; talk to a California land use attorney or tax adviser about your situation.
Sources & notes
- California Legislature (via LA County Planning): SB 450, Chapter 286, Statutes of 2024, chaptered text
- Permit Sonoma: Streamlined housing developments (SB 9)
- Permit Sonoma: Policy 8-0-6, SB 9 and split-zoned parcels
- Permit Sonoma: Subdivisions
- California HCD: Starter Home Revitalization Act fact sheet (April 2026)
- Los Angeles City Planning: SHRA (SB 684 and SB 1123) requirements
- Burke, Williams & Sorensen: SB 1123 revisions to SB 684
- California HCD: ADU ordinance review letter citing Gov. Code 66310 to 66342 (December 10, 2025)
- California HCD: Accessory dwelling units
- Allen Matkins: Builder’s remedy under AB 1893 and AB 1886
- California HCD: Housing Element Review and Compliance Report
- ABAG: SB 79 summary (last updated July 1, 2026)
- Allen Matkins: Governor approves SB 79
- Office of the State Fire Marshal: Fire hazard severity zones
The official statute pages on leginfo.legislature.ca.gov could not be opened during this review, so statutory points were checked against chaptered bill text, HCD documents and the agencies named above. State housing law changes every year; confirm the current text before relying on it.
Last reviewed October 2026 by Matthew Martinez.
