Overview

California created a faster way to subdivide certain infill properties into up to 10 smaller lots for housing. In Santa Rosa, this pathway is commonly referred to as SB 684 / SB 1123. It can be a real opportunity, but it is not a free-for-all. The rules are strict, and they exist for good reason: to protect residents, neighborhoods, and public safety.

This guide explains the basics in plain English and highlights the issues we see most often, especially for people trying to plan a purchase, a construction loan, or a small development.

1. What SB 684 and SB 1123 Actually Do

These laws require the City to process certain qualifying subdivisions through a ministerial approval process.

Ministerial means the City checks your project against objective, written standards. There is no subjective judgment, no discretionary public hearing, no political decision-making. The City applies clear rules and issues a decision based on whether you meet them.

Because the process is ministerial, it is generally treated as exempt from CEQA environmental review.

This is why people call it “by-right.” But that phrase deserves a word of caution. “By-right” only applies if you qualify and if your submittal is complete. It is not an automatic approval.

2. Where the Rules Apply in Santa Rosa (and When)

Santa Rosa summarizes the local applicability as follows.

SB 684 (effective July 1, 2024) applies in multifamily residential zoning districts, including R-2, R-3, and Multi-Family Planned Developments.

SB 1123 (effective July 1, 2025) expands the rules to allow certain projects in single-family residential zoning districts, including RR, R-1, and Single-Family Planned Developments.

A key SB 1123 limitation: the single-family site must be a vacant lot (more on what “vacant” means below).

3. The Basic Deal: Up to 10 Lots and Up to 10 Primary Homes

To qualify, your map must create 10 or fewer lots, and the housing project tied to that subdivision must include 10 or fewer primary residential units.

People often describe this as “one home per lot.” In practice, think of it as a project-wide cap: the overall project is limited to 10 primary homes.

Regarding ADUs and JADUs: the City is not required to allow ADUs or JADUs on these newly created lots. If the City does allow them, the law says ADUs and JADUs generally do not count toward the 10-unit limit.

4. Eligibility: The Parts That Matter Most

Santa Rosa requires projects to meet every item on its SB 684/1123 Eligibility Checklist. Here are the biggest make-or-break requirements, translated into plain English.

Zoning and Site Size Limits

To qualify, the site must be either multifamily-zoned and 5 acres or less, or single-family-zoned, vacant, and 1.5 acres or less.

Minimum Lot Sizes (Commonly Misstated)

If the property is multifamily-zoned, new lots must be at least 600 sq ft. If the property is single-family-zoned, new lots must be at least 1,200 sq ft.

This is one of the most frequently misquoted details. Many people assume 1,200 sq ft is the universal minimum. It is not.

City Water and Sewer Required

The lots created must be served by City water and wastewater services.

The Site Has to Be True Infill

At least 75% of the site’s perimeter must touch (or be across a street or highway from) parcels already developed with urban uses such as housing, commercial, institutional, transit facilities, or retail.

This is a built-in protection. It keeps these projects focused on infill neighborhoods rather than pushing new development into sensitive or undeveloped areas.

No Repeat Splits

Santa Rosa’s checklist states that the parcel cannot already have been created through an urban lot split (SB 9 pathway) or a prior subdivision under this same SB 684/1123 authority.

Ownership Structure Must Fit an Allowed Model

The housing units on the lot to be subdivided must be under one of these ownership frameworks: fee simple lots, common interest development, housing cooperative, community land trust, or tenancy in common.

This matters because it can affect title, subdivision mapping, and how a lender underwrites the collateral.

Minimum Density Requirement (A Hidden Eligibility Issue)

The law includes a “don’t underbuild” rule. If the property is listed in the City’s Housing Element site inventory, you generally must build at least the number of units projected for that site (and if it is counted toward certain affordability goals, there can be additional affordability requirements). If the property is not in the Housing Element site inventory, the project must generally reach at least 66% of the maximum allowable residential density.

This is one reason not every “10-lot idea” qualifies. On some sites, the minimum density requirement can force a unit count that does not fit under the 10-unit cap.

Starter Home Scale Limit

Santa Rosa’s checklist requires the average home size (net habitable area) across the project to be no more than 1,750 sq ft.

Safety and Protection Exclusions

Even if the zoning works, the site is not eligible if it falls within certain high-risk or protected categories. Examples include wetlands, very high fire hazard severity zones (as mapped), certain hazardous waste sites (unless properly cleared), earthquake fault zones (unless compliant with seismic safety rules), FEMA flood hazard areas or floodways (unless specific FEMA criteria are met), conservation easements or certain habitat and protected species areas, and sites that would require demolition or alteration of protected housing (affordable deed-restricted, rent-controlled, tenant-occupied within the prior five years, or Ellis Act withdrawals within the prior 15 years).

These exclusions are not red tape. They exist to protect people from predictable harm: fire, flood, instability, displacement, and environmental damage.

5. Timeline: When the City Must Decide

Under state law, the City must approve or deny a completed application within 60 days. If the City does not act within that time window, the application is deemed approved by law.

Santa Rosa also states it will issue an approval or denial within 60 days following application submittal, which, in practice, depends on you submitting a complete package.

6. The Santa Rosa Process (What Applicants Actually Do)

Santa Rosa lays out a straightforward sequence.

First, confirm eligibility using the City’s Eligibility Checklist. Second, consider a Pre-Application Meeting (recommended), where you submit the checklist and pre-app materials for early, interdepartmental feedback. Santa Rosa notes the pre-app form and eligibility checklist also satisfy the “Notice of Intent / Preliminary Application” requirement. Third, submit a complete SB 684/1123 application packet with all required materials. Fourth, the City issues approval or denial within the timeline. Fifth, after approval, proceed to building and/or engineering permits (building permits, encroachment permits, etc.).

7. A Very Important Financing Note: Limits on Splitting Collateral

There is a protection feature in the state law that borrowers and lenders must understand.

After you create lots under this program, the law generally prohibits selling, leasing, or financing the lots separately unless each lot meets specific conditions. Typically, this means the lot already has a legal residential structure or a completed new residential structure (or the lot is reserved for common/open space, or it is the last remaining undeveloped lot). The City can also authorize different treatment by ordinance or as a map condition.

Why this matters for your financing plan: it can affect how you plan your exit strategy (selling individual lots vs. building and selling homes), how construction draws and collateral releases are structured, and whether “lot-by-lot” financing is possible before vertical construction is complete.

This is exactly the kind of detail that protects communities from speculative “paper splits.” But it also means your financing plan must be designed with the law in mind from the start.

Common Misunderstandings (And the Truth Behind Them)

“It’s always 1,200 sq ft minimum lots.” Not true. Multifamily-zoned sites generally use a 600 sq ft minimum.

“By-right means automatic approval.” Not true. It means approval is rule-based, not discretionary. You still must meet every eligibility requirement and submit a complete application.

“If the map is approved, I can immediately finance or sell each lot separately.” Often not true. State law can restrict separate sale, lease, or financing unless specific conditions are met.

“This works on any lot in Santa Rosa.” Not true. Zoning, vacancy status (for single-family), utilities, infill perimeter, hazards, and protected housing rules all matter.

The Wisest First Move

If you are considering an SB 684 / SB 1123 project, the smartest place to start is not design. It is eligibility proof. Confirm zoning, lot size, vacancy status, utilities, infill perimeter, hazards, and Housing Element/density requirements early. That is how you protect your time, your capital, and your future residents.

This article is general information, not legal advice. Always confirm details with the City of Santa Rosa and qualified professionals, including land use counsel, a surveyor or civil engineer, an architect, and title/escrow.