Fontana permits ADUs in all residential and mixed-use zones. Pre-approved AB 1332 standard plans available. Permit fees waived for units under 750 sq ft. 60-day approval timeline standard.
Zoning & Size Requirements [1]
| Allowed Zones | All residential zones and mixed-use zones with residential |
| Max Size (Detached) | 1200 sq ft |
| Max Size (Attached) | 1200 sq ft or 50% of primary dwelling, whichever is less |
| Max Size (JADU) | 500 sq ft |
| Max Height | 16 ft (standard); 18 ft if within 1/2 mile of transit or 2-story home; 25 ft possible |
| Max Units | 1 ADU + 1 JADU per lot |
Setback Requirements [1]
| Rear Setback | 4 ft minimum (detached new construction) |
| Side Setback | 4 ft minimum (interior side, detached) |
| Front Setback | Base zone compliance |
| Parking Required | No additional required; no requirement for conversions |
| Owner Occupancy | Not required under state law |
| Min Lot Size | No specific state minimum |
Permit Process & Fees [2]
| Approval Process | Submit through Build Fontana online portal using pre-approved AB 1332 designs or custom plans |
| Review Timeline | ~60 days with pre-approved plans |
| Permit Fees | Waived for ADUs under 750 sq ft; fee applies for larger units (amount varies) |
| Impact Fees | Waived for units under 750 sq ft (SB 13); proportional for larger units |
| Plan Check | Included in 60-day timeline; faster with pre-approved designs |
| Pre-Approved Plans | AB 1332 standard ADU plans available on City website |
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Construction Costs
| Average Build Cost | $160,000-$270,000 |
| Cost per Sq Ft | $200-$250 |
| Garage Conversion | $75,000-$130,000 |
| Prefab ADU (Installed) | $80,000-$140,000 |
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Rental Income Potential
| Avg Rent (1 Bedroom) | $1,300-$1,700 |
| Avg Rent (2 Bedroom) | $1,700-$2,200 |
| Short-Term Rental | Subject to local ordinance; verify before planning |
| Est. Annual ROI | 7-10 year payback |
Explore Prefab ADU Options
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Recent Law Changes
What's Changed Recently
- AB 1332 pre-approved ADU designs streamline approval
- Permit fees waived for ADUs under 750 sq ft
- Height allows 18 ft near transit or 2-story homes
- Build Fontana online portal simplifies applications
Tips for Building an ADU in Fontana
- Use AB 1332 pre-approved designs for fastest approval
- Units under 750 sq ft have NO permit fees
- City website provides standard ADU plans for download
- Height flexibility near transit areas or 2-story homes
- Online permit process via Build Fontana reduces complexity
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Fontana Planning Department — ADU Information Planning Department — Accessed 2026-03-15
- Fontana Building Department — Permit Information building_dept — Accessed 2026-03-15
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