ADU Rules: Rancho Cucamonga vs Rialto
How do adu rules rules compare between Rancho Cucamonga, CA and Rialto, CA?
Rancho Cucamonga and Rialto have similar restriction levels.
Rancho Cucamonga, CA
San Bernardino County
Rancho Cucamonga must permit ADUs and JADUs on residential parcels under CA Gov Code 65852.2. Up to 1,200 sq ft detached or 50 percent of primary for attached, no owner-occupancy required statewide.
View full Rancho Cucamonga 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 | Rancho Cucamonga | Rialto |
|---|---|---|
| State authority | Gov Code 65852.2, mandatory statewide | - |
| Detached ADU max | 1,200 sq ft, 16 ft height by right | - |
| Attached ADU max | 1,000 sq ft or 50 percent of primary | - |
| JADU | Up to 500 sq ft carved from primary dwelling | - |
| Owner occupancy | Not required for state-law ADUs | - |
| 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.
Rancho Cucamonga FAQ
Do I need to live in the main house to build an ADU in Rancho Cucamonga?
No. State law eliminated owner-occupancy requirements for ADUs permitted under Gov Code 65852.2. JADUs still require owner occupancy of the primary or JADU.
Can I rent my Rancho Cucamonga ADU as a short-term rental?
State law requires ADUs to be rented for 30+ days. Short-term rental of an ADU is generally prohibited under Rancho Cucamongas STR rules and the ADU law.
How long does permitting take?
State law requires ministerial approval within 60 days of a complete application. Preapproved plans can reduce plan-check time significantly.
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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