What Is SB 684? California’s Starter Home Law Explained for Bay Area Buyers

SB 684 is a California law signed in 2023 and effective July 1, 2024. It requires cities and counties to fast-track approval for small housing developments of up to 10 homes on qualifying urban infill sites. No public hearings, lengthy environmental review or council votes.

The problem it was built to solve

California’s housing affordability gap is severe. The state’s home price-to-income ratio sits at 8.4, nearly double the national average of 4.7. In San Jose specifically, that ratio climbs to 11.65. The Bay Area is one of the most extreme examples of this problem anywhere in the country.

For decades, bureaucratic barriers have blocked the small-scale, attainable housing development that first-time buyers actually need. SB 684 targets that problem directly. It was designed to unlock starter home development at scale: smaller, naturally more affordable homes on underutilized urban land.

How it works: ministerial approval explained

The key mechanism behind SB 684 is ministerial approval. Here’s what that means in plain terms:

• The project is checked against objective standards: zoning rules and building codes
• No discretionary review, public hearings, or council votes required
• Cities must approve qualifying projects within 60 days, or the application is automatically deemed approved
• Projects are also exempt from CEQA (California’s environmental review process), which typically adds months or years to timelines

That 60-day window is significant. Bay Area permitting is notoriously slow. SB 684 puts a hard deadline on it.

Who Qualifies Under SB 684?

SB 684 has specific eligibility requirements. Not every lot qualifies, and understanding the criteria upfront saves time.

Eligible lot and zoning requirements

To qualify under SB 684, a site must meet all of the following:

• Zoned for multifamily residential use – per SB 1123, effective July 1, 2025, extended this to vacant single-family lots, more on that below
• 5 acres or smaller
• Substantially surrounded by qualified urban uses: residential, commercial, retail, or transit-adjacent development
• Located within an incorporated city or urbanized area
• Not previously subdivided under SB 684 or SB 9

Size and unit restrictions

The law also sets clear limits on what gets built. These limits are what keep SB 684 focused on starter homes rather than luxury development:

• Up to 10 new parcels and 10 residential units on the original site
• Each new parcel must be at least 600 sq ft
• Average net habitable floor area across all homes cannot exceed 1,750 sq ft
• Units can be sold as fee-simple lots, common interest developments, housing cooperatives, or community land trusts

That 1,750 sq ft average cap is intentional. It keeps these projects in the attainable range — the kind of homes that first-time buyers can realistically afford in high-cost markets like the Bay Area.

What SB 684 Means For Bay Area Homebuyers

SB 684 has direct implications for buyers in Silicon Valley. It isn’t just a statewide policy story.

More starter home options in Silicon Valley

Santa Clara County needs 129,577 new homes permitted by 2031. Most jurisdictions are falling well short of that target.

Most of Silicon Valley’s prime land was developed by the 1980s. Infill development on underutilized urban parcels is the only realistic path to meaningful new supply. SB 684 unlocks multifamily-zoned lots across the South Bay for small cluster developments of townhomes and cottages.

That creates a new category of attainable for-sale homes in cities like San Jose, Sunnyvale, and Campbell. A cluster of 8 to 10 townhomes on an infill lot can come in well below the $1M-plus single-family market that dominates Silicon Valley today.

Faster permitting, faster move-in

Bay Area permitting is notoriously slow and fragmented. San Jose, Palo Alto, Mountain View, and Sunnyvale each run their own independent permitting processes with separate requirements, timelines, and review standards.

SB 684’s 60-day mandatory approval window cuts through that complexity. Builders who already know each city’s local requirements can move even faster. Learn more about how long it takes to build a new home in the Bay Area and what affects your timeline.

SB 684 Vs. SB 1123: What’s The Difference?

Both laws are part of California’s broader Starter Home Revitalization Act framework. They work together to expand where and how starter homes can be built across the state.

Here’s how they differ in practice:

• SB 684: Effective July 1, 2024. Applies to multifamily-zoned parcels of up to 5 acres. This is the law already in effect across Silicon Valley.
• SB 1123: Effective July 1, 2025. Extends the same ministerial approval pathway to vacant lots in single-family zones of up to 1.5 acres. This opens up significantly more of California’s urban land.

The practical difference comes down to reach. SB 684 unlocks multifamily-zoned infill sites that were already intended for denser housing. SB 1123 goes further and opens up vacant lots in neighborhoods that previously had no pathway to small-scale development.

Together, they form a faster, more accessible approval system for starter homes across California.

AL Homes builds in the multifamily-zoned infill areas where SB 684 applies today, and is positioned to move quickly as SB 1123 continues to expand eligible sites.

How to Take Advantage of SB 684 in the Bay Area

SB 684 removes real bureaucratic barriers. But removing barriers isn’t the same as having a clear path forward. You still need a builder who can identify eligible sites, design within the law’s constraints, and execute construction without gaps.

Why working with a fully integrated builder matters

Most builders specialize in one part of the process. Some focus on land. Others on design. Others on construction. Each handoff between separate firms creates room for delays, miscommunication, and cost overruns that fall on the buyer.

A fully integrated builder handles all of it under one roof. That matters especially when working within SB 684’s 60-day approval window. One team managing land, design, permitting, and construction means fewer surprises and a faster path to move-in. Learn more about what to look for in a new home builder in California.

How AL Homes navigates permitting in-house