ADU Rules: Hesperia vs Rialto
How do adu rules rules compare between Hesperia, CA and Rialto, CA?
Hesperia and Rialto have similar restriction levels.
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 →Rialto, CA
San Bernardino County
Rialto allows ADUs on single-family and multifamily lots under California Government Code §66314 (formerly §65852.2), with local zoning standards in Rialto Municipal Code Title 18 (Zoning). State law preempts most restrictive local provisions: a detached ADU up to 1,200 sq ft and a JADU up to 500 sq ft are allowed by right on a single-family lot, plus the city must permit at least one ADU and one JADU per single-family parcel.
View full Rialto rules →Key Facts Comparison
| Fact | Hesperia | Rialto |
|---|---|---|
| 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) | - |
| Governing law | - | Cal. Gov. Code §66314 (state ADU statute) + Rialto Municipal Code Title 18 (Zoning) |
| Max ADU size (state floor) | - | 850 sq ft studio/1-BR; 1,000 sq ft 2+ BR; up to 1,200 sq ft allowed |
| Min setback | - | 4 ft side/rear (state preemption) |
| Approval timeline | - | 60 days ministerial review (Gov. Code §66317) |
| Permit office | - | Rialto Building & Safety, 150 S Palm Ave, (909) 820-2505 |
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.
Rialto FAQ
Can Rialto deny my ADU if I meet state standards?
No. State law requires ministerial (non-discretionary) approval if your ADU meets the objective standards in Gov. Code §66314 — Rialto cannot impose a public hearing or design review on a code-compliant ADU.
Do I need to live on the property to build an ADU?
No owner-occupancy is required for an ADU permitted between Jan 1, 2020 and Jan 1, 2025 under Gov. Code §66314(a)(6). JADUs always require owner-occupancy of either the main house or the JADU under Gov. Code §66333.
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