ADU Regulations in Fontana, California
Everything you need to know about building an ADU in Fontana — size limits, setbacks, permits, and costs.
How many ADUs are allowed in Fontana?
- → 1 Detached ADU (up to 1,200 sq ft)
- → 1 Attached ADU
- → 1 Junior ADU / JADU (up to 500 sq ft)
- → Up to 8 detached ADUs
- → Interior conversions up to 25% of existing units
All California cities must follow state-law minimums. Fontana follows California AB 68 and subsequent ADU laws.
Fontana ADU rules & limits.
| ADUs Allowed | Up to 3 units on a single-family lot (primary home + 1 ADU + 1 JADU); up to 8 detached ADUs on multifamily lots |
|---|---|
| Max ADU Size | 1,200 sq ft |
| Setbacks | 4 ft side & rear (CA state baseline) |
| Height | 16 ft detached, 18 ft permitted near transit corridors |
| Parking | Not required in most cases; no replacement parking for garage conversions |
| JADU Allowed | Yes — up to 500 sq ft; owner-occupancy required if JADU is present |
| Impact Fees | Waived under 750 sq ft (state law) |
| Permit Timeline | 60 days maximum (state-mandated review window) |
ADUs are permitted in R-1, R-2, and R-3 zones. Fontana is one of the most ADU-friendly cities in the western Inland Empire, with low impact fees and parking waived in most cases.
Contact: Fontana Building: (909) 350-6718
What could your Fontana ADU earn?
Rental estimates based on current Inland Empire market rates. Actual rents vary by condition, amenities, and local demand.
Four paths to an ADU in Fontana.
From idea to reveal.
Free Feasibility Consultation
We walk your lot, check setbacks and lot coverage, and confirm what your jurisdiction will approve.
Design & Engineering
Floor plan, elevations, structural calcs, and Title 24 energy compliance — drawn for your specific lot.
Permit Submission & Approval
We submit to your city or county, manage plan-check corrections, and pay the permit fees.
Construction
Same Construction Station crew handles foundation, framing, MEP, drywall, and finish — start to keys.
Final Inspection & Move-In Ready
Final city inspection, certificate of occupancy where applicable, and two-year workmanship warranty.
Why build an ADU in Fontana.
Fontana combines the largest population in the western Inland Empire with some of the most ADU-friendly regulations in California — low fees, multiple permitted zones, and waived parking. The newer north Fontana subdivisions have the ideal mix of large lots, modern utility infrastructure, and standardized construction details that keep ADU pricing predictable. Long-term rental demand is exceptionally strong: Fontana is home to the Mission Boulevard and Slover Avenue logistics corridor, with thousands of warehouse and distribution jobs, and the city sits within commuting distance of jobs in Ontario, Rancho Cucamonga, and San Bernardino. The 18 ft transit-corridor height allowance is particularly valuable for homeowners near the Fontana Metrolink station, where a two-story detached ADU becomes feasible on a standard suburban lot. Construction Station pulls permits in Fontana regularly.
Ready to build an ADU in Fontana?
We’ll walk your lot, confirm what Fontana will allow, and ballpark cost before you commit to anything.
Fontana ADU questions, answered.
How much does an ADU cost in Fontana?
How long does it take to get an ADU permit in Fontana?
Can I rent my ADU in Fontana?
Do I need owner-occupancy for an ADU in Fontana?
Does Construction Station build ADUs in Fontana?
ADU regulations change frequently. Always verify current requirements with the Fontana Planning Department at (909) 350-6718. This page was last updated May 2026.