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Zoning Guide

ADU Rules in Fontana

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ADU Rules in Fontana

Fontana permits Accessory Dwelling Units (ADUs) and Junior ADUs (JADUs) on residential properties under California state law (Government Code §65852.2) and the city's Zoning and Development Code. The city's ADU Information Sheet provides a summary of local requirements.

What You Can Build

Single-Family Lots (R-E, R-1, R-2)

  • One ADU (attached or detached) plus one JADU per lot
  • Detached ADU: up to 850 sq ft (studio/1-bed) or 1,000 sq ft (2+ bedrooms), or 50% of primary dwelling
  • JADU: up to 500 square feet within existing structure

Multifamily Lots (R-3, R-4, R-5)

  • Conversion ADUs: 1 ADU per 4 existing units converted from non-livable space
  • Detached ADUs: Up to 2 new detached ADUs per property

Size Limits

ADU Type Maximum Size
Detached ADU 850 sq ft (1 bed) or 1,000 sq ft (2+ bed)
Attached ADU 50% of primary dwelling or 850/1,000 sq ft
Junior ADU (JADU) 500 sq ft
Garage Conversion Existing footprint

Setbacks

  • Front setback: Must comply with base zone (22 ft in R-1)
  • Side setback: 4 feet minimum (per state law)
  • Rear setback: 4 feet minimum (per state law)
  • Conversion exception: ADUs in existing legal structures keep their current setbacks

Height

  • Detached ADU: 16 feet maximum
  • Attached ADU: Up to 25 feet
  • Near transit: 18 feet for detached ADUs within ½ mile of a major transit stop
  • ADUs on multifamily lots: up to 18 feet detached

Parking

A maximum of one parking space per bedroom may be required. Parking is not required when:

  • The ADU is within half a mile of a public transit stop
  • The ADU is within a historic district
  • The ADU is a conversion from existing space
  • A garage is demolished or converted for the ADU
  • On-street parking permits are required but not offered to the occupant

Owner Occupancy

  • ADUs: Not required (per AB 976)
  • JADUs: Owner must occupy either the JADU or primary residence

Rental Restrictions

ADUs in Fontana must be rented for terms of 30 days or longer. Short-term vacation rentals are prohibited.

Permit Process

ADU permits are processed through ministerial review with a 60-day maximum review period.

  1. Pre-application: Review your property's zone using the interactive zoning map
  2. Plan preparation: Prepare plans meeting California Building Code and Title 24 energy requirements
  3. Submit application: File with the Community Development Department
  4. Plan review: 60-day maximum for complete applications
  5. Permit issuance: Receive building permit and begin construction
  6. Inspections: Schedule required inspections during construction
  7. Final approval: Certificate of Occupancy upon passing final inspection

Contact the Planning Division at (909) 350-6718 for questions.

Fees and Costs

  • ADUs under 750 square feet are exempt from development impact fees
  • Building permit and plan check fees apply based on project scope
  • Utility connection fees may apply for detached ADUs requiring new service connections
  • Fire sprinklers are required only if the primary dwelling also has sprinklers

Key Considerations

  • Fontana has 27 Specific Plans that may affect your property — verify whether additional standards apply
  • Properties in Form-Based Code districts (downtown/corridors) may have different design requirements
  • Check for FEMA flood zones using the Flood Map Service
  • Solar panels are required on detached new-construction ADUs per California Energy Code
  • HOAs may impose design review requirements but cannot prohibit ADUs under California law

Official Resources

More about Fontana Zoning

Sources

  1. City of Fontana ADU Information Sheet·fontanaca.gov·Accessed 2026-04-04·Direct link
  2. Fontana Zoning and Development Code (Municode, Chapter 30)·library.municode.com·Accessed 2026-04-04·Direct link
  3. California Government Code §65852.2·leginfo.legislature.ca.gov·Accessed 2026-04-04·Direct link

FAQ

Can I build an ADU in Fontana?
Yes. Under California state law and Fontana's Zoning and Development Code, ADUs are allowed on all residentially zoned lots (R-E through R-5). You can build one ADU plus one JADU on a single-family lot.
What is the maximum ADU size in Fontana?
Detached ADUs can be up to 850 sq ft (studio/1-bedroom) or 1,000 sq ft (2+ bedrooms), or 50% of the primary dwelling's floor area. Attached ADUs follow the same limits.
Does Fontana require parking for ADUs?
A maximum of one parking space per bedroom may be required, but ADUs within half a mile of public transit are exempt. Garage conversions do not require replacement parking.