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California housing laws, explained for developers
State law now allows more homes on more sites, and approves them faster. This page covers what each law does and how to tell which one fits your site. It also covers the city programs layered on top.
Match the law to the site. A vacant infill lot points to SB 1123 (up to 10 homes); a single-family lot with a house points to SB 9 or ADUs; multifamily and mixed-use projects of five or more homes use the State Density Bonus Law; existing apartment properties add ADUs. Most of the gains come from combining them.
Up to 10 small-lot homes on a vacant parcel, approved in 60 days.
SB 9Split one single-family lot in two and build up to four homes.
Density BonusAdd 20–100% more units in exchange for some affordable homes.
ADU LawAdd rentable units behind houses and beside apartments, by right.
Which law fits your site?
Pick the closest description. This is a starting point; we confirm the path with a site feasibility study.
Start with SB 1123. Compare against SB 9.
- SB 1123 can yield up to 10 for-sale homes on separate small lots if the lot is vacant, 1.5 acres or less, and mostly surrounded by urban uses.
- SB 9 gives up to four homes after a lot split, but requires a three-year owner-occupancy affidavit.
- ADU law applies once a primary home is built, if the city allows ADUs on the new lots.
The four laws side by side
Statewide minimums. Cities can be more generous, but not stricter.
| Law | Typical site | New homes | Approval | Parking cap | Sell homes separately? | Affordable units required? |
|---|---|---|---|---|---|---|
| SB 1123 | Vacant single-family lot up to 1.5 ac, or multifamily-zoned lot up to 5 ac | Up to 10 lots / 10 homes | Ministerial, 60 days, no CEQA | 1 per home; 0 near transit | Yes, each home on its own lot | No |
| SB 9 | Single-family lot in an urbanized area | 2 per lot; up to 4 after a split | Ministerial, 60 days, no CEQA | 1 per unit; 0 near transit | Yes, after a lot split | No |
| Density Bonus | Any project of 5+ homes where housing is allowed | +20% to +100% over base density | Bonus is by right; rides on the project's own approval path | 1 / 1.5 / 2.5 by bedrooms; 0 near transit | Yes (rental or for-sale) | Yes, a share of units |
| ADU Law | Lots with a house, or with existing or planned apartments | House: ADU + JADU and more Apartments: up to 8 detached + conversions | Ministerial, 60 days, no CEQA | 0–1 per ADU | Only where the city has opted in (AB 1033) | No |
Stacking the laws
Several of these laws can be used together, and that's usually where the extra homes come from. We test these combinations on almost every site:
Duplex plus ADUs on a single-family lot
Without a lot split, SB 9 allows two homes and ADU law adds accessory units, which can mean three to four rentable homes on a lot that used to hold one.
Bonus apartments with ADUs on top
A density bonus project sets the unit count; ADUs on the same multifamily lot add rentable units outside that count, with no extra affordability.
Ten for sale, or four to hold?
On a vacant single-family lot, SB 1123 usually wins on unit count and sale value. SB 9 wins when there is a house worth keeping. We model both.
Cities have their own programs too
State law sets the floor. Most large California cities layer their own incentive programs on top, often tied to transit. We check the local program against state law on every site and use whichever one pencils.
Transit Oriented Communities (TOC)
- Tiered bonuses near major transit: Tier 2 adds 60% more units, more floor area and height, and lower parking.
- Affordability is set by tier, for example about 9% extremely low-income units in Tier 2.
- The incentives are being carried forward in the city's Citywide Housing Incentive Program (CHIP).
- ED 1 gives 100% affordable projects a ministerial, fast-track review.
- The Small Lot Subdivision ordinance has allowed fee-simple homes on small lots since 2005, long before SB 1123.
See Oakwood (TOC Tier 2) and Burnside (Small Lot Subdivision)
Enhanced Density Bonus (EDB)
- The city's alternative to the State Density Bonus Law, updated by City Council in June 2026.
- Extra bonuses and concessions for community benefits such as larger family units, senior housing or proximity to a park, up to a 120% total bonus.
- Applicants choose the city program or state law for a project, not both.
- Specific plans such as Midtown add their own transit-node rules, and the UPLAN rezoning opened North Long Beach corridors to new housing.
Near transit
- AB 2097: no minimum parking for most housing within a half mile of a major transit stop.
- Density bonus projects near major transit get lower parking caps, and 100% affordable projects there get unlimited density and extra height.
- Local programs often add their deepest bonuses in the same transit areas.
Being a quarter mile from a train station can matter more than the zoning map suggests.
Other large cities run their own programs too, and the rules change often. We read the current local ordinance, the state law and any specific plan before we recommend anything.
The full guides
- SB 1123: up to 10 small-lot homesVacant lots, 60-day ministerial approval
- SB 9: lot splits and duplexesUp to four homes from one single-family lot
- State Density Bonus Law20% to 100% more units, concessions and waivers
- ADU lawUp to eight detached ADUs on existing apartments
- Case studiesSix projects where the right program changed the outcome
Common questions
Which California housing law fits my site?
Start with what is on the land. Vacant lot up to 1.5 acres: SB 1123. Single-family lot with a house: SB 9 or ADUs. Five or more homes on multifamily or mixed-use land: the State Density Bonus Law. Existing apartments: ADU law, up to eight detached ADUs plus conversions.
Can California housing laws be combined on one project?
Yes, and that is where most of the gains come from. Density bonus projects can add ADUs, as on Pacific Avenue and Randall Avenue; small-lot projects can add ADUs, as on Burnside Avenue. Some combinations are barred: SB 1123 cannot be used on a lot already split under SB 9.
Do these laws require a public hearing?
SB 1123, SB 9 and ADUs are ministerial, decided by staff with 60-day deadlines. A density bonus project follows the city's normal path, but the city must grant the bonus, concessions and waivers it qualifies for.
Do cities have their own housing incentive programs?
Yes. Los Angeles has Transit Oriented Communities (carried forward in CHIP), ED 1 for 100% affordable projects and the Small Lot Subdivision ordinance. Long Beach has its Enhanced Density Bonus (updated June 2026), the Midtown Specific Plan and UPLAN zoning. We compare the local program against state law on every site.
How close to transit does a site need to be?
AB 2097 removes parking minimums for most housing within a half mile of a major transit stop, and density bonus and local programs add their deepest bonuses there. A quarter mile from a station can matter more than the zoning map suggests.
How do I find out how many homes my site can hold?
Send S² Architecture the address. We test the site against SB 1123, SB 9, the Density Bonus Law, ADU law and the local program, and tell you which path yields the most homes that still pencil out.
This page is general information, not legal advice. It summarizes California law as of October 2026. Cities adopt their own implementing ordinances, and eligibility depends on site-specific facts. Confirm with the local planning department and your land use counsel before acquiring a site.
Send us an address
Tell us where the site is and what you are hoping to build. We will tell you which of these laws applies and roughly how many homes it can hold.