California has been steadily rolling back barriers to ADU construction for years, and 2026 brings several key updates that make building an accessory dwelling unit more accessible than ever. Whether you're looking for rental income, a space for aging parents, or just more square footage, here's what you need to know about the current legal landscape.
SB 9 and Lot Splits: What Changed
Senate Bill 9, which allows lot splits and duplexes on single-family lots, continues to evolve. In 2026, the biggest change is streamlined ministerial approval — cities can no longer require discretionary reviews or public hearings for qualifying projects. If your lot meets the objective standards (minimum lot size, setback requirements), your application must be approved.
For ADU builders, this means less uncertainty and faster timelines. A lot split can create a separate parcel specifically for an ADU, unlocking financing options that weren't available before.
Height Limits: 16 Feet Is Now the Floor
State law now guarantees a minimum height of 16 feet for detached ADUs statewide, with up to 18 feet allowed if the property is within a half-mile of transit or if the ADU is above a garage. Some cities like San Diego have gone further, allowing up to 25 feet under certain conditions. This opens up two-story ADU designs that maximize living space on smaller lots.
Setback Relief
One of the most significant changes: rear and side yard setbacks for detached ADUs are now capped at 4 feet statewide. Many San Diego County properties that were previously ineligible due to narrow lots can now accommodate an ADU. Front setbacks still follow the primary residence rules, but the side and rear relaxation is a game-changer.
No More Owner-Occupancy Requirements
As of 2025, owner-occupancy requirements were suspended statewide through 2030. This means you can build an ADU on a rental property and rent out both units. For investors, this dramatically changes the ROI calculation — you're no longer required to live on the property.
Parking: Still Waived in Most Cases
Parking requirements for ADUs remain waived if the property is within a half-mile of public transit, in a historic district, or if the ADU is part of an existing structure (like a garage conversion). Even outside these zones, parking can be provided as tandem parking on an existing driveway — no need for new paving.
San Diego County Specifics
San Diego County has its own ADU ordinance that works alongside state law. Key local provisions include:
- Junior ADUs (JADUs): Up to 500 sq ft carved out of existing living space — think bedroom-to-studio conversion with a kitchenette.
- Pre-approved plans: The County offers pre-reviewed ADU plan sets that can cut permitting time by months.
- Fee reductions: Impact fees are waived for ADUs under 750 sq ft and proportionally reduced for larger units.
Financing Your ADU
Several financing paths have emerged specifically for ADUs. FHA's 203(k) renovation loan now covers ADU construction. CalHFA offers an ADU Grant Program providing up to $40,000 toward pre-construction costs. Some credit unions in San Diego offer construction-to-permanent loans tailored to ADU projects.
Is Now the Right Time?
With favorable laws, streamlined permitting, and strong rental demand in North County San Diego, 2026 is an excellent time to build an ADU. The regulatory environment has never been more supportive, and construction costs — while elevated — are stabilizing.
Every property is different. A free on-site consultation is the best way to understand what's possible on your lot. Learn more about our ADU services or schedule a consultation to get started.