What's the same across the Inland Empire
California state law sets a floor no city can go below: ministerial (no-hearing) review, a 60-day decision clock on complete applications, at least an 800 sq ft ADU with 4-foot side and rear setbacks, and size minimums of 850 sq ft (studio/1-bed) or 1,000 sq ft (2+ bed) that local caps can't undercut. Our California ADU laws guide covers the statewide framework, and the size & setback calculator shows the exact floors for your ADU type.
Two things stand out region-wide. Inland construction pricing generally runs below the coastal counties — see our cost guide. And IE terrain means fire-hazard and geo-hazard zones are a real factor: several cities exclude hazard-zone parcels from their fastest pre-approved paths, so confirming your parcel's status is an early, high-value step.
Where Inland Empire cities differ
Highlights from our city research — each links to the full city guide with sources and details:
| City | What stands out |
|---|---|
| Riverside | Dwell Riverside permit-ready plans for single-family zones — with a Cultural-Resource carve-out for historic properties, which follow separate design standards. |
| Corona | Publishes an ADU Regulations doc, a homeowner Guide Sheet, and a submittal flow chart; AB 1332 plan-preapproval is in its intake phase. |
| Moreno Valley | Seven free city-designed pre-approved detached plans (306–988 sq ft) — but only outside geo-hazard, landslide, flood, and Wildland-Urban Interface zones. |
| Temecula | Free Permit-Ready ADU (PRADU) plans and a strict citywide short-term-rental ban that includes ADUs — plus a two-track submittal and an advance new-address requirement. |
| Murrieta | An unusually transparent impact-fee formula (proportional to your home's size above 750 sq ft), a Pre-Approved ADU Program, and by-right permitting; 1,200 sq ft detached cap. |
| Menifee | A generous 1,500 sq ft ADU maximum, eight permit-ready plans, and a fire water-supply exemption for units under 600 sq ft — with High Fire Severity Zone rules on some parcels. |
| Rancho Cucamonga | Publishes its own ADU Handbook and skips the separate planning-application step — building permits are the path. Foothill parcels may hit fire-zone rules. |
| Ontario | Preapproved plans, all-electronic submittal via the Citizen Portal, and a five-department plan check that includes the city's own utility (OMUC). |
| Fontana | Standard ADU Plans plus a homeowner-favorable size rule — the larger of 50% of the main house or the 850/1,000 sq ft state floors. |
| Chino | A published flat $452 plan-review fee and a 7–10 business-day review window, with an added Chino Valley Fire District review step. |
| Chino Hills | A Fire Hazard Overlay that raises building separation to 30 ft (waived for 100% non-combustible builds), an ADU Ineligibility District for some parcels, and separate utility meters for detached units. |
| Upland | Free permit-ready ADU plans in set sizes (440/484/741 sq ft) plus a dedicated step-by-step homeowner site (uplandadu.org); foothill parcels may carry fire-zone rules. |
All 12 Inland Empire city guides
Riverside County (Riverside, Corona, Moreno Valley, Temecula, Murrieta, Menifee) and San Bernardino County (Rancho Cucamonga, Ontario, Fontana, Chino, Chino Hills, Upland) — more IE cities are being researched and added.
Before you start in any Inland Empire city
- Check your hazard-zone status first. Fire-hazard (WUI), geo-hazard, landslide, and flood zones can add construction requirements and exclude your lot from the fastest pre-approved plan paths — this is the single most IE-specific gotcha.
- Ask about free or standard pre-approved plans. Moreno Valley gives away seven; Ontario, Fontana and Rancho Cucamonga run programs. Where you qualify, it's the biggest design-cost saving available.
- Confirm which utility and fire district review your plans. Ontario's OMUC and Chino Valley Fire District are extra reviewers that affect timelines many homeowners don't budget for.
- Watch for HOAs in newer tracts. Much IE housing is newer master-planned development — read our HOA guide before designing.
How this page is built: every city-specific claim above is drawn from our individual city guides, each researched from that city's official planning resources and municipal code, with state-law context from the California HCD ADU framework. City programs and ordinances change — the linked city guide is always the more detailed reference, and your city's planning department is the final authority. This page is general information, not legal advice, and doesn't guarantee what your specific property qualifies for. See also our Los Angeles County and Orange County guides.