ADU Rules: Ontario vs San Bernardino
How do adu rules rules compare between Ontario, CA and San Bernardino, CA?
San Bernardino has fewer restrictions than Ontario.
Ontario, CA
San Bernardino County
Ontario must allow ADUs and JADUs under California Gov Code 65852.2 and 65852.22 on all single-family and most multifamily lots. Approval is ministerial within 60 days, with no minimum lot size.
View full Ontario rules →San Bernardino, CA
San Bernardino County
San Bernardino permits ADUs on single-family and multi-family lots under CA Gov Code 65852.2. Detached ADUs up to 1,200 sq ft and JADUs up to 500 sq ft are ministerially approved.
View full San Bernardino rules →Key Facts Comparison
| Fact | Ontario | San Bernardino |
|---|---|---|
| State law | Gov Code 65852.2 and 65852.22 | - |
| Size | Up to 850-1,000+ sq ft detached | - |
| Setbacks | 4 ft side and rear | - |
| Parking | Waived near transit, half mile | No parking required within 1/2 mile of transit |
| Approval | Ministerial, 60 days | Ministerial, 60-day review, no discretionary hearing |
| Legal authority | - | CA Gov Code 65852.2 statewide ADU mandate |
| Standard ADU | - | Up to 1,200 sq ft detached, 850 to 1,000 sq ft for attached |
| JADU | - | Up to 500 sq ft inside existing home with owner occupancy |
Highlighted rows indicate differences between cities.
Ontario FAQ
Can Ontario deny my ADU application?
Only if the project fails the objective state-law or local standards. Otherwise state law requires ministerial approval within 60 days of a complete application.
Do I have to live on site to build an ADU?
No. State law suspends owner-occupancy requirements for ADUs permitted through January 1, 2025, a window that has been extended further by subsequent legislation.
San Bernardino FAQ
Does San Bernardino approve ADUs over the counter?
Yes. State law requires ministerial approval within 60 days of a complete application, with no discretionary hearings or subjective design review.
Do I have to live on the property to rent my ADU?
Owner occupancy is required for Junior ADUs. Standard ADUs permitted after 2020 are not subject to owner-occupancy rules until state law changes.
Can I rent my ADU on Airbnb?
State law generally requires ADU rentals be 30 days or longer, so short-term rental use is typically prohibited.
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