ADU Rules: Hesperia vs Ontario
How do adu rules rules compare between Hesperia, CA and Ontario, CA?
Hesperia has fewer restrictions than Ontario.
Hesperia, CA
San Bernardino County
Hesperia permits one ADU plus one JADU per single-family lot under HMC 16.12.360 (Article 16.16 for JADUs), with detached ADUs up to 1,200 sq ft, JADUs up to 500 sq ft, and 4-foot side/rear setbacks - implementing California Gov. Code 66314 et seq.
View full Hesperia rules →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 →Key Facts Comparison
| Fact | Hesperia | Ontario |
|---|---|---|
| Code Section | HMC 16.12.360 (ADU); Article 16.16 (JADU) | - |
| Max Detached ADU | 1,200 sq ft | - |
| Max Attached ADU | 50% of primary, up to 1,000 sq ft | - |
| Max JADU Size | 500 sq ft | - |
| Side/Rear Setback | 4 feet | - |
| Max Detached Height | 16 ft (18/25 ft per state law in qualifying cases) | - |
| 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 |
| Approval | - | Ministerial, 60 days |
Highlighted rows indicate differences between cities.
Hesperia FAQ
Can I build an ADU on my single-family lot in Hesperia?
Yes. HMC 16.12.360 permits one ADU plus one JADU on every single-family residential lot, with detached ADUs allowed up to 1,200 sq ft and JADUs up to 500 sq ft.
What setbacks apply to a detached ADU in Hesperia?
Side and rear setbacks are 4 feet under HMC 16.12.360. Front setbacks match the underlying zoning district. Conversion ADUs and JADUs only need sufficient fire-safety separation.
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.
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