SB-9 is often talked about, but rarely executed—especially in San Diego. I worked with a client who explored not just SB-9 or ADUs, but how both could work together on a single property. In this case study, I walk through their real timeline from planning to approval, the decisions that shaped the project, and the realities behind costs, complexity, and feasibility. This isn’t theory—it’s a firsthand look at what it actually takes to combine SB-9 and ADU development in 2026.
Understanding SB9 and ADU: What the Client Considered First
When a client asked me how to best maximize their property value, we started by clearly comparing SB-9 and ADU development options. Both paths offer real opportunities, but they operate under different rules—and understanding those differences is critical before moving forward.
Key differences in regulations and eligibility
SB-9 applies only to eligible single-family zoned parcels and allows either the creation of up to two primary units or a ministerial lot split, which can ultimately support additional units. ADUs are more flexible and can be built on both single-family and multi-family properties with fewer location-based restrictions. SB-9 eligibility is still limited in certain hazard and protected areas, while ADU laws apply more broadly across California. As of recent updates, local jurisdictions are no longer allowed to require owner-occupancy for ADUs, removing a barrier that previously slowed some projects.
Why ADUs felt easier at first
From a practical standpoint, ADUs appeared to be the more predictable path. State law now enforces clearer approval timelines, and many cities offer pre-approved ADU plans that can significantly shorten review periods once a complete application is submitted. Fee reductions and ministerial approvals also made ADUs feel more straightforward compared to SB-9, which many cities are still adapting to.
What made SB-9 worth the added complexity
Despite the learning curve, SB-9 stood out for its long-term upside. Under current law, a properly executed SB-9 lot split—combined with ADUs where allowed—can result in up to four total units on a single property. This flexibility often unlocks more value than a standalone ADU project. While local implementation still varies, recent state clarifications have reduced some of the friction that initially slowed SB-9 adoption.
Planning the project: from idea to blueprint
Once we committed to pursuing both SB-9 and ADU strategies, planning became more layered. Success depended on early collaboration with architects experienced in both regulations and proactive coordination with city planners. Reviewing preliminary layouts before formal submission helped address setbacks, parking, and unit configuration early—saving time later. Even as SB-9 processes continue to mature, careful planning and informed design remain the key to moving these projects forward efficiently.
How SB9 and ADU Rules Come Together in Los Angeles: From Early Planning to Final Occupancy
Success on this combined SB9 and ADU project started with assembling the right team. Our client partnered with an architect experienced in SB9 regulations and engaged city planners early to review preliminary concepts before formal submission. That upfront collaboration helped identify zoning and design issues early—critical in jurisdictions where SB9 standards are still evolving. Designing for dual compliance required balancing SB9 requirements with ADU regulations, including four-foot side and rear setbacks, parking accommodations, and unit sizing. With most homes centered on their lots, creative site planning was essential, and larger parcels proved far more workable for SB9 development.
While SB9 promises ministerial approvals within 60 days, real-world timelines often look different. This project required coordination across Planning, Building & Safety, Engineering, and Fire, extending design and permitting to roughly four to five months. The execution phase added further complexity: lot split approvals, utility “Will Serve” letters, easement documentation, and multiple inspection milestones for the ADU construction. From permit submission through final Certificate of Occupancy, the full process took close to seven months. It’s a clear reminder that while SB9 and ADUs unlock powerful housing opportunities in California, successful outcomes depend on experienced professionals, realistic timelines, and proactive navigation of local approval processes.
Combining SB9 and ADU Development: Was it Worth it?
Our client analyzed the financial results after finishing their project that combined SB9 and ADU development. The findings shed light on what this dual-approach strategy could mean for others who might want to try it.
Total units added and property value effect
Our client tapped into their property’s full potential by combining SB9 with ADU development. They created four units in total—two primary units through SB9 and two ADUs. This strategy led to a dramatic increase in their property’s value. FHFA analysis shows California properties with ADUs reached median appraised values of $1,064,000, while properties without ADUs stood at $715,000. On top of that, properties with ADUs saw annual appreciation rates of 9.34% compared to 7.65% for those without.
Rental income potential and ROI
The rental income numbers look impressive. Los Angeles ADUs typically bring in $2,000-$3,500 monthly. The client’s annual ROI from rental income reached 10.5%, and this is a big deal as it means that traditional investment options fell short. The client explained that rental income combined with property appreciation makes a strong financial case for this development approach.
Would the client do it again?
The client says yes, but with a few conditions. While ADU development thrives with over 5,000 permits in Los Angeles alone, SB9 projects remain rare because cities have added extra requirements. The client pointed out that this combined approach works best with larger lots.
Conclusion
Combining SB-9 and ADU development isn’t common, but I’ve seen firsthand how powerful it can be when done right. This project required patience—about 4–5 months of planning and seven months of construction—but the payoff was significant. Four legal units on one lot dramatically increased property value and produced a 10.5% annual ROI from rental income alone. This approach isn’t for every property. Lot size, local regulations, and the right professional team all matter. But for owners who can navigate the complexity, pairing SB-9 with ADUs is one of the smartest ways I know to unlock density, value, and long-term returns in California.
