What You Need to Know About the 2025 Bonus ADU Regulation Reforms in San Diego
Introduction
In June 2025, the San Diego City Council approved sweeping reforms to the city's Bonus ADU program—transforming rules governing how many accessory units you can build on single-family lots. These changes reshape eligibility, density, fees, and safety requirements, and could impact many planned ADU projects nationwide.
At ADU Pals, we’re committed to keeping you informed and helping you make smart decisions before these new rules take full effect.
What’s Changed: Key Reform Highlights
Effective mid-2025, the City enacted a package of 25 ADU and JADU regulatory updates, including major modifications to the ADU Home Density Bonus Program
1. Cap on Units Based on Lot Size
San Diego now limits the total number of ADUs/JADUs a single-family lot can support based on lot size:
Up to 4 units (excluding primary home) on lots ≤8,000 sf
Up to 5 units on lots between 8,001–10,000 sf
Up to 6 units on lots >10,000 sf
2. Affordability-Based Bonus Limits
Bonus units will still be possible—but only in exchange for deed-restricted affordable ADUs. Outside Transit Priority Areas (TPAs), you’re now limited to one bonus ADU per affordable ADU. Inside TPAs, unlimited bonus units remain possible—but still capped by lot size and new restrictions
3. New Infrastructure, Safety & Parking Requirements
Community enhancement fees for ADUs under 750 sf using bonus rules
Off-street parking mandatory for units outside TPAs
Minimum 5-foot setbacks in High Fire Hazard Severity Zones (5′ replacing prior 4′)
Two-story cap on detached ADUs in single-family zones
Restrictions on cul‑de‑sac lots in high wildfire-risk areas lacking multiple evacuation routes
4. Grandfathering Provision
Projects with permits approved and fees fully paid before the June 16 vote are generally grandfathered in under previous rules, though secondary legal review is ongoing.
Why the Council Made These Changes
Originally hailed as a housing-forward incentive, the Bonus ADU program sparked backlash when developers built multi-ADU “granny towers” in single-family neighborhoods. Concerns focused on neighborhood character, parking strain, traffic, and fire safety.
Opponents argued the program had strayed far beyond state ADU law requirements and needed recalibration. The Council's 5-4 vote reflects a shift toward limiting density—even as the city grapples with housing shortages.
What These Reforms Mean for You
Still Allowed:
Standard state-law ADUs: 1 detached ADU (≤800 sf), 1 converted ADU (garage/etc.), and 1 JADU, per single-family household (totaling up to three plus primary residence).
Curtailed:
Bonus units beyond the one-to-one model—with new caps by lot size and zone.
Unlimited ADUs near transit are now subject to density ceilings.
Additional fees and stricter design standards in wildland/fire risk zones.
Strategic Implication:
Projects submitted and deemed complete before the June 16 vote are likely safe, but any new applications must meet the updated requirements.
What Should You Do Next?
Act now if you're planning a Bonus ADU —complete and permit under old rules.
Expect higher costs, review timelines, and approvals for all future projects.
Work with ADU Pals to confirm your lot’s status (transit zone, fire zone, lot size, etc.) and navigate the new requirements.
Watch for updates from HCD, as the California Housing Department is evaluating some of these reforms for compliance with state law and AFFH (fair housing) obligations.
How ADU Pals Can Help
We stay fully up to date on San Diego’s evolving ADU ordinance.
We review site eligibility—including transit access, lot size, and fire hazard zones.
We design, plan, and submit projects that meet both current and future regulatory requirements.
We expedite projects before changes take full effect.
Conclusion
San Diego’s Bonus ADU reforms represent a significant regulatory pivot—balancing housing production and neighborhood impact. While state-law ADUs remain available, the feedback-heavy changes limit incentives previously available to multi-unit builders.
Want help navigating these new rules, assessing your lot, or acting before the grandfathering window closes?
