ADU Regulations in Rialto, California
San Bernardino County · CA · Pop. 105,000
Max ADU Size
1,200
sq ft detached
Rear Setback
4 ft
Permit Timeline
60 days
Build Cost
$130,000 – $265,000
Zoning
Allowed ADU Types
State law preempts local owner-occupancy requirements. Rialto's residential zones feature large lots by Southern California standards, well-suited for detached ADUs. One ADU plus one JADU permitted per single-family lot.
Source: City of Rialto — Accessory Dwelling Units · Rialto Municipal Code Title 18 (Zoning)
Dimensions
Size & Setback Requirements
Detached
1,200
sq ft max
JADU
500
sq ft max
Attached
50% of primary home, max 1,200 sq ft
Setbacks
front
Same as primary dwelling
side
4 ft
rear
4 ft
Max height: 16 ft
Lot coverage: Per underlying zone
Rialto's Inland Empire lot sizes frequently exceed 7,000 sq ft, giving ample space for detached ADUs in rear yards. ADUs converted within an existing garage retain the structure's existing setbacks.
Permitting
Permit Process
Department
City of Rialto Community Development Department — Planning Division
Review Timeline
60 days
Permit Fees
$5,000 – $10,500
Impact Fees
Impact fees waived for ADUs under 750 sq ft per state law
Required Documents
- ›Site plan
- ›Floor plans
- ›Elevations
- ›Title 24 energy compliance
- ›Structural drawings
- ›Soils report (if required by site conditions)
Rialto maintains streamlined ADU processing per state law. Lower land costs and fees compared to Los Angeles or Orange County make ADU ROI strong in this Inland Empire city. Contact the Community Development counter for current fee schedule and pre-application availability.
Visit City of Rialto Community Development Department — Planning Division →Infrastructure
Utilities & Requirements
Solar
Required
Parking
Not required
Separate Meter
Optional
Fire Sprinklers
See note
Financials
ADU Costs in Rialto
Typical Build Cost
$130,000 – $265,000
Cost per Sq Ft
$185 – $245
Monthly Rental
$1,300 – $2,000/mo/mo
Property Value Added
Adds $130,000 – $240,000 to property value
Available Grants & Programs
- ★CalHFA ADU Grant Program available
- ★San Bernardino County housing assistance programs
Rialto is an Inland Empire logistics hub with major Amazon fulfillment centers and warehouse employers driving steady housing demand from working families. Lower land and construction costs relative to coastal cities make Rialto one of California's most affordable ADU markets with solid rental returns.
Use the free ADU Cost Calculator →Free Service
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Rialto Quick Facts
- Max size1,200 sq ft
- Rear setback4 ft
- Permit timeline60 days
- Build cost$130,000 – $265,000
- Rental income$1,300 – $2,000/mo/mo
- Owner occupancyNot required
Official Source
City of Rialto — Accessory Dwelling UnitsRialto Municipal Code Title 18 (Zoning)
Last verified: March 14, 2026
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ADU rules change often.
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