Getting a garage conversion permitted by the City of Simi Valley
How a Simi Valley garage conversion is permitted by the City of Simi Valley Building & Safety: the steps, state ADU deadlines, and Ordinance 1349 under review.
Garage conversions in Simi Valley are permitted by the City of Simi Valley Building & Safety, not by Ventura County. The County's building department covers unincorporated areas, which includes some addresses with a Simi Valley mailing address such as parts of Santa Susana Knolls; everything inside city limits goes to the City.
Which rules apply depends on the path. A living-space or office conversion is reviewed as an alteration to your house under City code. A garage ADU is reviewed under state ADU law, Government Code sections 66310 to 66342, which overrides conflicting local rules.
The permit steps in order
Most delays come from the first two steps being rushed, so they get the most time:
- Measure the garage and record existing conditions, including the water heater, panel and drains.
- Choose the path: living space, office or studio, legalization, or ADU.
- Prepare plans and any required calculations for Building & Safety.
- Submit, answer plan check comments and pay the City's fees.
- Build, with inspections at each stage the City calls for.
- Final inspection; for an ADU, a Certificate of Occupancy before anyone lives there (Gov. Code 66328).
Deadlines the City must meet on a garage ADU
For an ADU application, the City has 15 business days to make a written completeness determination or the application is deemed complete, and it must approve or deny a complete application within 60 days when a house already stands on the lot (HCD ADU Handbook, March 2026; Gov. Code 66317). A denial must include a full set of comments from every reviewer explaining how to fix it.
HCD's October 29, 2025 letter told Simi Valley that its ordinance wording, under which the City would 'act on' an application within 60 days, did not match state law, which requires an actual approval or denial. These deadlines apply to ADUs. A plain living-space conversion follows the City's ordinary plan check timeline.
Local rules in flux: Ordinance 1349 and its replacement
Simi Valley's ADU rules come from Ordinance No. 1349, given its second reading June 5, 2023. HCD found 19 conflicts with state law in October 2025, and Ordinance No. 1373 is the City's replacement. Read any Ordinance 1349 standard as superseded pending Ordinance 1373, including the partial-garage rule that keeps a 12 by 20 foot parking space in a partly converted attached garage.
| Finding | What Ordinance 1349 said | What state law requires |
|---|---|---|
| 1, statutory numbering | Cited Gov. Code 65852.2 and related sections | Cite Gov. Code 66310 to 66342 |
| 3, approve or deny | The City would act on an application within 60 days | Approve or deny within 60 days |
| 5, living area | Counted garages as living area | Garages are not living area (Gov. Code 66313) |
| 15, unpermitted structures | Conversions limited to legally permitted accessory structures | Unpermitted structures can convert unless they threaten health and safety and are affected by the work |
Questions homeowners ask
Does Ventura County issue my garage conversion permit?
No, not for a Simi Valley address. The City of Simi Valley Building & Safety handles building permits inside city limits.
Can the City reject my garage ADU over local design rules?
For a conversion unit under Gov. Code 66323, the City may not apply development or design standards that section does not list, including local parking, height and setback rules (HCD ADU Handbook, March 2026). Building code and fire and safety setbacks still apply.
Who pulls the permit, me or the contractor?
On jobs Aguila contracts, Aguila pulls the permit under its license, so inspections and corrections run through the contractor rather than through you.
What happens at the final inspection?
The inspector checks the finished work against the approved plans. When it passes, the permit is finaled, and that is what makes the converted space legal. An ADU also needs a Certificate of Occupancy before anyone moves in.
Sources
Facts on this page last verified: .
- California HCD, Accessory Dwelling Unit Handbook, March 2026: https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf (2026-10-05)
- HCD findings on Simi Valley ADU Ordinance No. 1349, letter of October 29, 2025: https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/ordinance-review-letters/simi-valley-adu-findings-102925.pdf (2026-10-05)
- City of Simi Valley, second reading of Ordinance No. 1349, staff memo of June 5, 2023: https://simivalley.granicus.com/MetaViewer.php?view_id=5&clip_id=2792&meta_id=204582 (2026-10-05)
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