Downey, CA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Downey, CA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Multifamily conversion cap
- Up to 25% of existing units, min. one
- Convertible spaces
- Garages, storage rooms, basements, attics
- Single-family path
- One of two ADUs may be a conversion
- Expansion allowance
- Up to 150 sq ft for entrance access
- Parking impact
- Converted-garage ADU exempt from added space
Summary
Downey lets homeowners convert garages and other non-livable space into ADUs under § 9414.10(a)(3): on multifamily lots, up to 25% of existing units, but at least one, can come from converting garages, storage rooms, basements, or attics, while single-family conversions run through § 9414.08.
§ 9414.10(a)(3): Up to 25% of the existing number of units developed as part of the multifamily dwelling within the multifamily structure, but at least one ADU, can be converted from existing attached or detached areas that are not used as livable areas. These areas shall include, but are not limited to, storage rooms, boiler rooms, passageways, attics, basements, common areas, garages, or detached accessory structures. ADUs shall comply with Building Code standards for dwellings. § 9414.08(a)(1): A maximum of two ADUs can be permitted on a single-family lot. ADUs may be a combination of: (A) one attached or detached, new-construction ADU; and (B) ADU resulting from the conversion of an existing habitable area or space not used as livable area.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4807734; v5 updated 2026-01-27).
Full Breakdown
10(a)(3), governing lots developed with an existing multifamily dwelling, allows converting existing attached or detached space that is not used as livable area into an ADU: up to 25% of the existing number of units developed as part of the multifamily dwelling, but at least one ADU, can be converted from existing attached or detached areas that are not used as livable areas, including storage rooms, boiler rooms, passageways, attics, basements, common areas, garages, or detached accessory structures. Any such conversion still has to meet Building Code standards for dwellings, since turning a garage into habitable space triggers the same fire, electrical, plumbing, and egress requirements as new construction.
08(b)(6), which exempts space converted from a permitted attached or detached structure from the maximum ADU size limits and allows up to a 150-square-foot expansion solely to accommodate proper ingress and egress. 14(a)(1)(iii) exempts an ADU that is part of an existing accessory structure from the one-space parking requirement. 16(d) requires the City to review the demolition permit concurrently with the ADU application and issue both permits together, rather than requiring demolition first.
Violations & Fines
Converting a garage to living space without an approved ADU or JADU permit is both a zoning violation and a Building Code violation, since the work bypasses required fire, egress, and habitability inspections. The Building and Safety Division can red-tag an unpermitted conversion, require it to be restored to garage use or brought into compliance under § 9414.20, and withhold final occupancy until the structure meets Building Code standards for dwellings.
Frequently Asked Questions
Can I convert my garage into an ADU in Downey?
How many units in a Downey apartment building can be converted from garages into ADUs?
If I convert my garage to an ADU, do I need to replace the parking space?
Sources & Official References
Other rules in Downey
California rules heatmap·Compare Downey to another location·View the California accessory structures overview
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Garage Conversions in Nearby Cities
How other cities in Los Angeles County handle garage conversions.