In June 2025 the San Diego City Council voted 5–4 to cap the ADU Home Density Bonus Program, reversing a 2020 policy that had allowed a nearly unlimited number of bonus units on a single lot. The change took effect about 30 days after final passage for properties outside the Coastal Zone.
If you watched the Short above and want to know what it means for your specific property, here is the practical version.
The new unit caps
The cap counts total units on the lot, not bonus units alone:
| Lot size | Maximum total units |
|---|---|
| 8,000 sq ft or less | 4 |
| 8,001 – 10,000 sq ft | 5 |
| More than 10,000 sq ft | 6 |
For the large majority of San Diego single-family lots, which fall under 8,000 square feet, that means four units total.
Eight zones lost the program entirely
The Bonus ADU program was prohibited outright in the city's lowest-density residential zones — RS-1-1, RS-1-2, RS-1-3, RS-1-4, RS-1-8, RS-1-9, RS-1-10 and RS-1-11 — except in areas the City designates as highest- or high-resource. Those zones covered roughly a quarter of the land that had been eligible.
Zoning is parcel-specific and not something to guess at. Look up your parcel's zone on the City's zoning map before you plan around a bonus unit.
What did not change
This is the part the headlines skipped, and it's the part that matters to most homeowners. The rollback applied to the Bonus program — the density-bonus track used mainly to add multiple rental units. The standard ADU allowances under California state law were not cut. On a typical single-family lot that still means the ability to add a detached ADU, plus a conversion of existing space, plus a junior ADU.
In other words: if your plan was one backyard ADU for family, rental income, or aging parents, this rollback almost certainly does not stop you. If your plan was four or five units on a standard lot as an investment play, it does.
It's also worth knowing that state law moved in the opposite direction at the same time. California's 2026 ADU law changes put cities on a deadline to process applications and widened the fee exemptions for smaller units — so the city tightened density while the state loosened process.
What it costs to actually build one
Permits and fees for a San Diego ADU typically run $14,000–$22,000 all-in — plan check, permit, school fees and utility connections combined. ADUs under 750 square feet are exempt from impact fees under state law, which is a meaningful saving and one reason so many San Diego ADUs are designed just under that threshold. Construction cost sits on top of that and varies widely with size, site access and whether you're building new or converting.
Rules change, and this page reflects what we could verify as of August 2026. Always confirm current requirements for your specific parcel with the City of San Diego Development Services Department before committing money to a design.
Sources: City of San Diego — City Council Adopts Reforms to Accessory Dwelling Unit Program · KPBS — San Diego City Council approves rollback of ADU incentives · City of San Diego — ADU/JADU Information Bulletin 400