SB 9 Explained for Alamo Homeowners

Thinking about splitting your Alamo lot or adding a second unit to create more value or flexibility? California’s SB 9 opened a new path for many single-family properties, and Alamo homeowners are asking what is actually possible on hillside parcels with unique utility and access needs. You want a clear, local answer before you invest time or money. In this guide, you’ll learn what SB 9 allows, how Contra Costa County applies the rules in unincorporated Alamo, and the practical steps to move from idea to approval. Let’s dive in.

What SB 9 allows

Ministerial approvals

SB 9 creates a ministerial process for two things on qualifying single-family parcels: an urban lot split and up to two residential units. Ministerial means no discretionary public hearing and only objective standards apply. Local agencies must use clear, measurable rules and cannot apply subjective design review to qualifying projects.

Lot splits and duplexes

You can pursue a lot split, add up to two units on a qualifying lot, or both when local rules allow. In many cases, an owner can split a parcel and then build two units on one or both resulting lots. Each approval is processed ministerially if all objective standards are met, and your exact sequence and submittals depend on County procedures.

Key state guardrails

The state sets limits to prevent overuse or unsafe conditions. There is a one-time SB 9 split cap per original parcel. Parcels in certain protected areas or with recorded restrictions may be ineligible. SB 9 projects are typically ministerial and often outside discretionary CEQA review, but sensitive locations can change that outcome. For statutory details, review the California SB 9 bill text and the California Department of Housing and Community Development’s SB 9 guidance.

How SB 9 works in Alamo

Zoning and overlays

Alamo is unincorporated, so Contra Costa County Planning administers SB 9. Your parcel must be in a single-family zone that participates in SB 9. Parcels with recorded restrictions, conservation designations, or historic status can be excluded. Start by confirming your zoning, overlays, and any recorded covenants.

Hillside and slope checks

Much of Alamo sits on rolling or steep terrain. Slopes affect buildable area, grading, retaining walls, and stormwater management. Steep slopes can trigger geotechnical studies or hillside standards that may remove ministerial eligibility and shift the project to a discretionary track. Ask the County for a slope overlay check and whether any hillside development permit applies.

Frontage and emergency access

Each new lot must have legal access and meet emergency vehicle standards. Frontage, driveway width, turnarounds, and fire apparatus access are common pinch points, especially for flag or irregular lots. If a proposed parcel lacks legal access, the County can deny a lot split or require easements and documentation.

Utilities and septic

Serviceability can make or break a project. Many SB 9 approvals require letters or will-serve confirmations from your water and sewer district. If your property uses septic, County Environmental Health will require proof of feasible design, separation, and reserve areas for additional units or new lots. Some septic parcels cannot be split if standards cannot be met. Plan for potential main extensions, meter upgrades, impact fees, and utility easements.

Environmental and fire overlays

Fire hazard, floodplain, creeks, wetlands, and protected trees all factor into site design. In Alamo, many parcels fall in moderate to very high fire hazard zones, which affect access, defensible space, sprinklers, and hydrant requirements. You can review statewide hazard designations through Cal Fire’s Fire Hazard Severity Zone resources. Creek setbacks or riparian rules can also limit where you build or whether a split is feasible.

Early rules to verify

• One-split-per-parcel cap under SB 9, confirm no prior SB 9 split.
• Minimum lot size or percentage rules often apply, a common rule is each new parcel must be at least 40 percent of the original lot area, confirm the County’s exact threshold.
• Owner declarations may be required, review County forms for any owner-occupancy affidavits or recorded notices.
• Title matters, check for recorded covenants, easements, or historic resource status that can bar SB 9.
• Objective standards still control, confirm setbacks, height, lot coverage, parking, and landscape requirements before you draw plans.

Step-by-step submittal

Pre-application

A focused pre-application with Contra Costa County Planning is the best first step. Confirm zoning, overlays, driveway and frontage standards, and submittal requirements. Contact your water and sewer district and fire authority early to understand capacity, hydrant spacing, and fire flow. Clarify whether the County will require a geotechnical report or arborist review based on your slope and trees.

Required documents

Counties often ask for a consistent set of materials for SB 9 lot splits and two-unit projects:

• Completed County SB 9 application form for ministerial lot split or two-unit approval.
• Preliminary title report with ownership, easements, and recorded restrictions.
• Legal descriptions for the existing parcel and any proposed new parcels.
• Site plan or parcel map showing existing conditions, proposed lines, setbacks, topography, building footprints, driveways, parking, frontage, and easements.
• Floor plans and elevations for new units or conversions.
• Utility service confirmations, will-serve letters for water and sewer, or septic feasibility from County Environmental Health.
• Stormwater and erosion control plan, especially on slopes and where new impervious area is added.
• Tree impact assessment if protected trees may be removed.
• Geotechnical or soils report where slope thresholds are exceeded.
• Fire access and protection documentation that addresses driveway width, turnouts, hydrants, and defensible space.
• Signed owner affidavit and any required County notices acknowledging SB 9 limits.
• Fees for applications, mapping, plan check, and utility connections.

Timeline at a glance

A simple ministerial SB 9 project can move in a few months if utilities are available and no hillside or septic issues are present. Pre-application and document prep often take 2 to 6 weeks. Initial completeness review commonly runs 2 to 4 weeks, followed by coordinated reviews for utilities, fire, and environmental health. If objective standards are met and no discretionary permits are triggered, the County can issue a ministerial approval. Parcel maps must be recorded before sale or further development.

Cost and timing expectations

Plan for design and professional reports first. On hillside parcels, you may need geotechnical studies, grading plans, and an arborist report. The biggest cost drivers are often utility connections, main extensions, driveway reconstruction for fire access, stormwater compliance, and potential fire-safety upgrades. Timeline and budget expand when septic feasibility is limited, slopes are steep, or a discretionary hillside permit is required.

Quick eligibility checklist

Use this simple screen before you invest in full plans:

• Is the property in an eligible single-family zone per Contra Costa County?
• Has the parcel been split before under SB 9?
• Are there recorded covenants, conservation easements, or historic designations that prohibit splitting?
• Will each new lot have legal access and required emergency frontage or driveway width?
• Is slope manageable based on County overlays, and is a geotechnical report feasible?
• Is public sewer and water available, or is septic expansion feasible for two lots or units?
• Are there protected trees, wetlands, creeks, or floodplain constraints?
• Is the property in a fire hazard zone that will add access or mitigation requirements?
• Will objective standards for setbacks, height, coverage, and parking allow your concept?

If your answers trend positive, schedule a pre-application with the County Planning Division.

Your next step

SB 9 can unlock value in Alamo, but local slopes, utilities, fire access, and tree protections make the path highly site-specific. The right team will help you confirm eligibility, assemble the correct reports and letters, and submit a clean ministerial package that stays on timeline. If you want an integrated approach that pairs brokerage strategy with permitting and build execution, our family team can help from concept through construction and sale.

Ready to explore your options or get a quick eligibility screen for your parcel? Reach out to Woehrle Real Estate & Development for a local SB 9 consult.

FAQs

What is SB 9 and how does it help homeowners?

• SB 9 creates a ministerial path for an urban lot split and up to two residential units on a qualifying single-family parcel, subject to objective standards and state guardrails.

Can I split my Alamo lot and build four units?

• Combining a lot split with two units on each resulting lot can be possible, but you need County confirmation on sequencing and compliance before assuming four units will be approved.

Do slopes or protected trees block SB 9?

• Not automatically, but steep slopes and tree protections often trigger reports or standards that can remove ministerial eligibility and add time and cost.

What if my property is on septic in Alamo?

• Septic feasibility is a common limiting factor and the County must verify that design and setbacks meet standards for more units or new lots.

How long does an SB 9 approval take in Contra Costa County?

• Straightforward ministerial projects can move in a few months, while hillside, septic, or utility extension needs can extend timelines significantly.