An Overview of Senate Bill 684 (SB-684)

For decades, building for-sale homes at a small scale in California was nearly impossible, not because the opportunity wasn't there, but because the approval process made it too slow, too uncertain, and too expensive. Senate Bill 684 (SB-684), signed into law in October 2023 and effective July 2024, changed that. For the first time, small developers can subdivide vacant or underused parcels in existing residential neighborhoods, and build up to ten for-sale homes, each on their own lot, through a fast, predictable process that bypasses the hearings and political delays that canceled qualified housing development projects before they ever broke ground. 

What is SB-684?

California’s development approval process has long given local governments broad discretion to approve, delay, or cancel housing development projects, whether this be through public hearings, planning commission votes, and lengthy environmental review. Senate Bill 684 strips that discretion away for qualifying projects by requiring the ministerial approval process for a housing development project through a parcel map, including tentative and final maps, for 10 or fewer residential units. Through ministerial approval, you avoid public hearings, political votes, and subjective judgments that have stalled or canceled projects in the past. If the boxes are checked, the permit must be issued. The law creates this pathway for up to ten homes on qualified multifamily infill sites: urban land that has long been overlooked due to outdated planning and zoning law, and slow approvals.

Qualifying projects are also exempt from CEQA, the California Environmental Quality Act, the state’s primary environmental review law. This law normally requires developers to study and prepare an environmental impact report for the project, a process that can take years and be used by opponents to stall housing development. Projects that take advantage of SB 684 can bypass CEQA entirely.

What makes SB 684 structurally significant is that it extended ministerial approval to subdivision maps for the first time in California. Before this new legislation, several laws expedited building permits, but splitting a single lot into separate parcels required going through the traditional discretionary process. SB 684 closes that gap by requiring local government to consider parcel map approval ministerially for development projects, including accessory dwelling units, without discretionary review, when they create 10 or fewer residential units on fewer parcels. Now, a developer can subdivide and build through a single, no-hearing process, making for-sale housing finally feasible at a small scale.

Why does this matter?

California’s severe housing shortage has been widely estimated at roughly 3.5 million homes. However, this crisis goes beyond numbers. Homeownership has always represented more than a place to live. It’s stability, a sense of belonging, and a milestone that generations of Californians have worked toward. But that milestone has been slipping further out of reach. California’s homeownership rate has been declining for years, and the state now has one of the lowest in the country.

To really understand the issue, we have to look more closely at the types of housing development projects being built in the state. California has been building large single-family houses and large apartment complexes, leaving an enormous gap between single-family residential development and larger multifamily projects. Modest, attainable for-sale homes on smaller lots, the kind that first-time buyers and working families can actually afford, have been nearly impossible to finance, permit, and construct under the old approval system. The risk and cost of discretionary review made small projects economically unviable.

SB-684 targets that gap directly. By unlocking small-scale for-sale housing, the law creates a new supply of entry-level homes for ownership in existing neighborhoods that are close to jobs, transit, and schools, without requiring the conversion of open land or the displacement of existing residents. It won’t solve the housing crisis alone, but it opens a door that has been effectively closed.

What parcels are eligible?

Not every site zoned for multi-family residential use qualifies. The law is intended to incentivize infill development while maintaining existing protections against tenant displacement and against development on environmentally sensitive sites. SB-684’s eligibility criteria are specific, and all of them must be met. Before submitting an application, the lot proposed to be subdivided and any proposed subdivision must satisfy objective subdivision standards, and a developer needs to be able to check every box.

• Zoning. The site must be a legal parcel located in a multifamily zone and be no larger than five acres. If other criteria are met, that parcel may support a proposed housing development, including accessory dwelling units. Single-family zoned lots don’t qualify under SB-684, though SB-1123 (2024) extended similar provisions to vacant single-family lots. These lots must be 1.5 acres or less and have a minimum parcel size of 1,200 square feet.
• Urban Context. The site must be substantially surrounded by qualified urban uses. In statutory terms, it must be in a qualified urban area and be surrounded by qualified urban development, such as homes, apartment buildings, shops, offices, or transit facilities. This ensures SB-684 is used for true development on overlooked urban lots, not the conversion of open or agricultural land. Sites that are bordered by farmland, open space, parks, undeveloped land, or federal property will likely not meet this requirement.
• Location. The site must be located within an incorporated city or qualifying urbanized area. Rural and unincorporated land in smaller counties generally won’t qualify.
• No Re-Splitting. The lot proposed to be subdivided cannot have been previously created through SB-684 or an SB-9 lot split. The law cannot be used to repeatedly subdivide the same parcel.
• Environmental Constraints. Lots located in high fire hazard zones, wetlands, protected habitat, or land under conservation easements are all disqualified. Flood plains, earthquake fault zones, and hazardous waste sites require additional local agency review and documentation to qualify.
• Anti-Displacement. Projects cannot involve the demolition or alteration of rent-controlled units, deed-restricted affordable housing, or any housing that has been tenant-occupied within the last five years. Sites where an owner previously used the Ellis Act, a state law that allows landlords to permanently remove all units from the rental market, are also disqualified if that withdrawal happened within the past fifteen years.

What housing development project can you build?

Picture a vacant half-acre lot in an existing neighborhood surrounded by apartments, a corner store, and a bus stop. Before SB-684, that lot might have sat undeveloped for years, too small for a large apartment complex and too complicated for a small developer to navigate the approval process. Under SB-684, that same lot could become a housing development project consisting of eight modest starter housing units, each on its own newly created parcel, each sold individually to a first-time buyer.

SB-684 is designed to produce small, attainable for-sale homes on urban land that would otherwise go underdeveloped. The law sets clear boundaries on what can be built:

• Parcels. A lot can be subdivided into up to 10 new parcels for the proposed housing units.
• Units. The development may contain no more than 10 residential units in total.
• Parcel Size. Under the Starter Home Revitalization Act, newly created parcels for multifamily residential development must be at least 600 square feet, while parcels in single family residential zones must be at least 1,200 square feet, unless a local agency allows smaller sizes.
• Unit Size. The average unit size across the project cannot exceed 1,750 net habitable square feet. Keeping these homes modest and attainable by design.
• Density. Projects must build at the density the site calls for, and which zoning law requires. If the site is listed in the housing element or specified master plan, the development must be consistent with the adopted housing element’s projected housing units. For all other sites, the project must be built to the maximum allowable residential density.

Note: AB 130 (2025) added one important provision: if there is already a permanent structure on the property, like an existing home, the developer can set that portion aside as a remainder parcel. It stays untouched while the rest of the lot is developed and doesn’t count against the ten-parcel limit. This opens up a much wider range of properties that previously wouldn’t have qualified simply because something was already built on them.

In terms of ownership, SB-684 supports fee-simple lots, condominiums, housing cooperatives, and community land trusts. A homeowners association is not required unless otherwise mandated. For most SB–684-qualified projects, fee simple can be the primary draw: each buyer owns their land outright, financing is conventional, and homes can be sold individually.

With SB-684, cities are not obligated to permit accessory dwelling units (ADUs) or junior accessory dwelling units (JADUs) on parcels created under the law.

How do streamlined approval processes work?

Before SB-684, even a small housing project could spend years in the approval pipeline waiting for a myriad of local ordinance processes: hearing dates, navigating planning commission feedback, and hoping a city council vote went the right way. That uncertainty alone could be enough to kill most small projects before they start.

SB-684 replaces that uncertainty with a simple rule: if your project meets the criteria, it gets approved. No hearings, no commission votes, no subjective judgment. Once a completed application is submitted, the local agency receives it and has 60 days to approve or deny a parcel map or tentative map. If a local agency denies the application, it must provide a written explanation of exactly what’s missing and how to fix it within that same 60-day window; if no decision is made, the application is deemed approved. In processing the proposed subdivision, the applicable local government acts local agency pursuant to the Subdivision Map Act.

SB-684 also created an early-building-permit pathway. Upon tentative map approval, a developer can submit a building permit application and begin construction before the final map is officially recorded, and the streamlined process applies to parcel maps as well as tentative and final maps, shaving meaningful time off the overall development timeline.

These minor lot subdivision rules are a matter of statewide concern and rely on objective standards that the Subdivision Map Act requres, and local agencies cannot impose minimum parcel dimensions or homeowners’ association requirements.

What are the limitations?

SB-684 presents a handful of challenges that are worth considering alongside its opportunities.

• Qualifying sites can be rarer than they appear. The law’s eligibility criteria are layered and cumulative, and the ministerial pathway is most useful for projects with 10 or fewer residential units, not larger ones. Fire hazard zones, floodplains, tenant history, and environmental constraints eliminate a significant share of otherwise-zoned multifamily land, particularly in coastal cities and fire-prone regions where demand is highest. Finding a site that clears every hurdle can be a challenge.
• Tenant protection matters. SB-684 includes meaningful anti-displacement protections. Sites with recent tenant history, rent control, or Ellis Act withdrawals within the past fifteen years are not eligible. It is important to verify a site’s tenant history early in the process before moving forward
• City readiness varies. SB-684 is self-executing; cities are bound by it whether or not they’ve updated their internal procedures. But in jurisdictions that haven’t trained staff or updated application checklists, developers may encounter inconsistent interpretations and informal resistance. As more projects move through the pipeline, this will smooth out over time.
• Inclusionary housing obligations still apply. SB-684 does not exempt projects from local inclusionary housing ordinances. If a site is designated in the city’s housing plan to serve lower-income households, the project must deliver those affordable units with a recorded restriction of at least 45 years.

Despite these constraints, the benefits are significant. For the first time, small developers have a guaranteed, fast-track path to build for-sale homes on urban infill land without the risk of discretionary denial, though the process is still governed by existing laws on subdivision development. The CEQA exemption alone removes years of potential delay. The early building permit pathway compresses the construction timeline. And the law’s support for community land trusts and housing cooperatives opens the door to ownership models that have historically struggled to move through traditional approval processes.

SB-684 won’t work everywhere, and it won’t work for every developer. But for the right site and the right project, it removes barriers that have made small-scale for-sale housing increasingly more difficult to build in California.

How does SB-684 compare to SB-9?

SB-9 and SB-684 are often mentioned in the same breath, and for good reason, as both laws use ministerial approval to streamline certain housing developments in California. But they target different problems, different sites, and different types of builders.

SB-9 is fundamentally a homeowner tool. It applies to single-family zoned lots and allows an owner to split their lot into two parcels and build up to four units total. The catch is that the owner must live on one of the resulting lots for at least three years. It’s designed for the individual homeowner who wants to add a unit, split off a portion of their lot, or create a small duplex, not for a developer building from scratch. For a deeper dive, check out our full overview of SB-9.

SB-684 operates at a different scale and targets a different audience. It applies to land zoned for multifamily residential development, covers 10 or fewer residential units and a proposed lot split into 10 or fewer parcels, and has no owner-occupancy requirement. A developer can acquire a vacant urban site or one with an existing structure and pursue a proposed subdivision or parcel map to build an entire small subdivision of for-sale homes through a single streamlined process. Where SB-9 unlocks individual backyards on sites in single family zones, SB-684 unlocks underused infill land on multifamily sites for small-scale residential development.

Think of them as complementary tools rather than competing ones. SB-9 is for homeowners looking to maximize the value of the land they already own in neighborhoods zoned for single-family residential uses. SB-684 is for builders looking to develop small for-sale projects on infill sites in areas zoned for multi-family residential uses. California needs both.

How do I get started?

Type Five's new tool infillworks, lets you see what's possible on your property, evaluate feasibility, and costs. From there, Type Five can help customize the design and help build your home.