Thinking about turning your San Luis Obispo single-family lot into two homes or two lots? You have likely heard that SB 9 can fast-track duplexes and lot splits, but the local steps in SLO City and County can feel confusing. This guide gives you the key numbers, local checkpoints, and a simple plan you can follow. Let’s dive in.
SB 9 creates a ministerial path to add up to two primary units on an eligible single-family lot or to split one legal lot into two lots. In the right setup, an original parcel can support up to four primary units over time. SB 9 approvals are ministerial, which means no discretionary hearings and CEQA exemptions for qualifying projects, under the state code that governs SB 9 two-unit developments and urban lot splits. See the statutory framework in California Government Code for details on owner-occupancy and tenant protections.
For full context, review the SB 9 provisions in the California Government Code and the County’s SB 9 program page.
Your property must be within a U.S. Census urbanized area or cluster and located on a legal single-family lot. Start by running your address on the County’s SB 9 eligibility map and reviewing the objective standards and application steps published by San Luis Obispo County.
Parcels in certain areas are ineligible, such as regulatory floodways, prime farmland, wetlands, very high fire severity zones, or critical habitat areas. The City of San Luis Obispo codifies these exclusions in its Urban Lot Split ordinance.
A large share of SLO County lies within the California Coastal Zone. In these areas, SB 9 must be consistent with the certified Local Coastal Program. In practice, that can add steps or pause approvals until local and Coastal Commission certifications align. Check the County’s SB 9 housing hub page to confirm Coastal Zone status and current coastal implementation notes.
The City’s Urban Lot Split standards are in Municipal Code Chapter 16.15. Expect objective standards for setbacks, lot design, and access, plus clear map recordation requirements. The code also distinguishes qualifying split types and applies state exclusion criteria.
San Luis Obispo County updated its SB 9 regulations in 2025. The County requires a pre-screening checklist, a site layout plan, an owner-occupancy affidavit for lot splits, and it caps total dwellings per resulting parcel. The County’s program page includes an interactive eligibility map, step-by-step instructions, and required forms.
Pre-screen and eligibility check. Use the jurisdiction’s SB 9 map and complete any pre-screen forms.
Submit your application. For lot splits, file a tentative parcel map and required affidavits. For duplexes, apply for building permits. The County also requires a Cost Accounting Agreement to start review.
Ministerial staff review. The agency checks objective standards and statutory constraints. If your submittal is complete and compliant, it moves to approval without a discretionary hearing. Under SB 450, local agencies must act on SB 9 applications within 60 days.
Record the parcel map for lot splits. Once the map is recorded within the allowed window, you can pull building permits for the new lots.
Expect weeks to a few months for straightforward cases. Parcels with septic, Coastal Zone, or utility easement issues can take longer.
Good fit if you have a conforming single-family parcel, reliable sewer access, and no exclusion conflicts. You may add up to two primary units on an eligible lot under the SB 9 two-unit development path. Design to objective standards and check parking and access early.
This strategy creates two legal lots, each with its own path to primary units. You must meet the minimum lot size rule and sign the three-year owner-occupancy affidavit. Confirm frontage or easement standards and title implications before you draw a tentative map.
In the right setup, a split followed by two primary units per lot can yield up to four primary units over time. This often requires the most coordination on utilities, access, and site layout. In SLO County, coastal status, septic capacity, and deed restrictions are the main variables to solve first.
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