ADU Regulations in Simi Valley, California
Ventura County · CA · Pop. 130,000
Max ADU Size
1,200
sq ft detached
Rear Setback
4 ft
Permit Timeline
60 days
Build Cost
$155,000 – $310,000
Zoning
Allowed ADU Types
ADUs are permitted by right on single-family and multifamily residential lots. Simi Valley's R-E (Residential Estate) zone allows ADUs on larger rural-style lots throughout the city's northern hillside areas. Many planned developments (RPD) include CC&Rs — state law prohibits ADU bans but aesthetic standards may still apply.
Source: City of Simi Valley — Accessory Dwelling Units · Simi Valley Municipal Code Chapter 9-50 (Accessory Dwelling Units)
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 (detached); up to 25 ft if attached or above garage
Lot coverage: Per underlying zone; R-1 typically 40%
Simi Valley's hillside lots in the northern part of the city may require geotechnical review for ADUs with new foundations. Lots in the valley floor neighborhoods are predominantly flat and spacious, facilitating straightforward detached ADU construction.
Permitting
Permit Process
Department
Planning and Regulatory Department
Review Timeline
60 days
Permit Fees
$7,000 – $14,000
Impact Fees
Impact fees waived for ADUs under 750 sq ft; Simi Valley Unified School District school fees assessed separately
Required Documents
- ›Site plan with lot lines, setbacks, and utilities
- ›Floor plans
- ›Elevations
- ›Title 24 energy compliance
- ›Structural drawings
- ›Geotechnical report (hillside lots only)
Simi Valley's planning department is known for responsive customer service and has published a clear ADU guide on its website. Ventura County Fire Department (VCFD) provides fire review. The Reagan Library, located just outside the city, draws steady tourism but the primary ADU rental market is long-term residential.
Visit Planning and Regulatory Department →Infrastructure
Utilities & Requirements
Solar
Required
Parking
Not required
Separate Meter
Optional
Fire Sprinklers
See note
Financials
ADU Costs in Simi Valley
Typical Build Cost
$155,000 – $310,000
Cost per Sq Ft
$215 – $280
Monthly Rental
$1,700 – $2,700/mo/mo
Property Value Added
Adds $145,000 – $280,000 to property value
Available Grants & Programs
- ★CalHFA ADU Grant Program available (up to $40,000 for pre-development costs)
- ★Ventura County Community Development Block Grant programs
Simi Valley is a family-oriented bedroom community with strong long-term rental demand from households priced out of the San Fernando Valley. Its valley-floor neighborhoods offer large lots at lower land costs than comparable LA County communities, making ADU returns competitive. The SR-118 freeway corridor provides direct access to employment centers throughout the region.
Use the free ADU Cost Calculator →Free Service
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Nearby Cities in Ventura County
Simi Valley Quick Facts
- Max size1,200 sq ft
- Rear setback4 ft
- Permit timeline60 days
- Build cost$155,000 – $310,000
- Rental income$1,700 – $2,700/mo/mo
- Owner occupancyNot required
Official Source
City of Simi Valley — Accessory Dwelling UnitsSimi Valley Municipal Code Chapter 9-50 (Accessory Dwelling Units)
Last verified: March 14, 2026
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