Simi Valley, CA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Simi Valley, CA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Code section
- SVMC 9-44.160(E)(1)–(2), A(11), A(17)
- Setback relief
- Same footprint = no new setbacks required
- Ingress/egress bonus
- Up to 150 sq ft expansion allowed
- Replacement parking
- Not required when a garage is converted to an ADU
- Partial garage conversion
- Remaining space must keep parking if ≥ 12 × 20 ft
- State preemption
- Cal. Gov't Code § 65852.2
Summary
Simi Valley ministerially allows an attached or detached garage to be converted to an ADU under SVMC 9-44.160(E)(1): no additional setbacks are required when keeping the existing footprint, and lost garage parking is generally waived under state law.
Detached ADUs may be new construction in yards subject to setbacks outlined in Section B or the conversion of a legally permitted accessory structures, such as a studio, shed, carport, horse stable, garage, or pool house, can be converted to an ADU. The existing space of an accessory structure within which an ADU is proposed to be located must have a solid roof and structural framing. In addition, the structure must have been permitted as required by the Simi Valley Municipal Code. Construction beyond the existing space of the accessory structure must meet all current requirements of the Simi Valley Municipal Code. An accessory structure, including a demolished and reconstructed structure that is being fully or partially converted to a detached ADU, may be expanded by up to 150 square feet to accommodate ingress and egress, so long as this expansion does not increase the nonconformity of the structure. ... Where an existing legally permitted accessory structure, or existing living area, is converted to an ADU or an ADU constructed in the same location, and to the same dimensions as an existing structure, no additional setbacks will be required.
Full Breakdown
160(E)(1) (Ord. No. 1316), 'Detached ADUs may be new construction in yards subject to setbacks outlined in Section B or the conversion of a legally permitted accessory structures, such as a studio, shed, carport, horse stable, garage, or pool house, can be converted to an ADU. The existing space of an accessory structure within which an ADU is proposed to be located must have a solid roof and structural framing. ' Subsection (E)(2) allows an additional 150 sq ft expansion 'to accommodate ingress and egress' so long as nonconformity is not increased.
160 Table). If an attached garage providing required SFD parking is only partially converted, the remaining space must continue to be used for parking if at least 12 ft by 20 ft (subsection A(11)). 2 preempts Simi Valley from requiring replacement parking when a garage is converted to an ADU.
Violations & Fines
Occupying a converted garage as an ADU without a Zoning Clearance, building permit, and California Building Code compliance can trigger code enforcement and require removal of habitable improvements; converting a garage that was not legally permitted in the first place forfeits the relaxed setback and parking allowances.
Frequently Asked Questions
Can I convert my detached garage into an ADU in Simi Valley?
Do I have to replace the lost parking spaces?
Can I expand the garage as part of the ADU conversion?
Sources & Official References
Other rules in Simi Valley
California rules heatmap·Compare Simi Valley to another location·View the California accessory structures overview
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Garage Conversions in Nearby Cities
How other cities in Ventura County handle garage conversions.