Short answer: If you need more space than an ADU allows, California's SB 9 may be the better path. SB 9 lets homeowners split their lot or build a second full-sized unit, with more square footage than an ADU, two-story options, 4-foot setbacks, and an expedited permitting process. In this Bay Area case study, a San Jose family used SB 9 to add a 2,000-square-foot two-story home without demolishing their original house. Key Takeaways ADUs have limits: Strict regulations often