You bring the ADU plans to the counter and the planner says the unit will need one off-street parking space — and since you are converting the garage, the two spaces it held have to be replaced somewhere on the lot. It sounds official, and it sinks the project, because there is nowhere left to put three cars. Before you redraw anything, check the address against a transit map. In a great many California neighborhoods, both halves of that statement are wrong as a matter of state law.
The short answer: a California city may never require more than one parking space per ADU, or per bedroom, whichever is less, and it may require none at all in six listed situations — including when the ADU is within one-half mile walking distance of public transit, or is created inside the existing house or an existing accessory structure (§ 66322). Cities also may not require replacement parking when a garage is converted or demolished to build one.
Key numbers
| Rule | Limit | Where it comes from |
|---|---|---|
| Maximum parking a city may require | 1 space per ADU or per bedroom, whichever is less | ADU Handbook, Parking Requirements |
| Guest parking | Never required for an ADU | ADU Handbook, Parking Requirements |
| Transit exemption | Within one-half mile walking distance of public transit | § 66322 |
| Car share exemption | Car share vehicle within one block | § 66322 |
| Replacement parking after a garage conversion | Cannot be required | ADU Handbook, Parking Requirements |
| Junior ADU parking | Cannot be required, even converting an attached garage | ADU Handbook, JADUs |
The ceiling: one space, at most
State law does not require you to build parking. It limits how much a city may demand. Parking requirements for ADUs "shall not exceed one parking space per unit or bedroom, whichever is less," and those spaces may be provided as tandem parking on a driveway — one car behind the other (ADU Handbook, Parking Requirements).
Two details inside that sentence matter:
- "Whichever is less" means a one-bedroom ADU maxes out at one space, and a studio maxes out at one space. An "efficiency unit" or studio has no bedrooms, so it does not increase the bedroom count.
- Guest parking spaces shall not be required for ADUs under any circumstances. If a local ordinance asks for a guest space on top of the resident space, it is asking for something state law forbids.
Because this is a ceiling and not a floor, a city is free to go lower — and many have, requiring half a space or none at all. The state describes reducing or eliminating ADU parking as a way to remove barriers to construction.
Where parking is required, the city must be flexible about where it goes. Off-street spaces for the ADU are to be permitted in setback areas in locations determined by the local agency, or through tandem parking, unless the agency makes specific findings based on site conditions, topography, or fire and life safety.
The six situations where a city can require none
A local agency shall not impose any parking standards for an accessory dwelling unit in any of the following instances:
The list from § 66322:
- The ADU is located within one-half of one mile walking distance of public transit.
- The ADU is within an architecturally and historically significant historic district.
- The ADU is part of the proposed or existing primary residence, or of an accessory structure — the converted-space case.
- On-street parking permits are required but not offered to the occupant of the ADU.
- There is a car share vehicle located within one block of the ADU.
- The ADU permit application is submitted together with an application for a new single-family or multifamily dwelling on the same lot, provided the ADU or the parcel also satisfies one of the criteria above.
Note the wording of the first one: walking distance, not a straight-line radius. A stop that is 1,800 feet away as the crow flies but a mile on foot around a freeway is not within a half mile walking distance. Where a city measures it as a radius, ask which method its ordinance actually uses.
The third one is the quiet workhorse. Any ADU created inside the existing house — or inside an existing detached garage, barn or workshop — is exempt from parking outright, regardless of transit. Conversions are the single most common ADU type in California, and most of them owe no parking at all.
Converting the garage: no replacement required
This is the rule that most often gets stated backwards at the counter. Where a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU, or converted to an ADU, the local agency shall not require those off-street parking spaces for the primary unit to be replaced (ADU Handbook, Parking Requirements).
So the two spaces your garage used to hold do not have to reappear in the side yard. This is separate from the ADU's own parking question — and since a garage conversion is also "part of an existing accessory structure" under the exemption list above, the usual answer for a garage-conversion ADU is that no parking is required in either direction.
Two categories that are exempt by definition
Junior ADUs. A local agency may not require parking as a condition of permitting a JADU, even when the JADU is converted from an attached garage (ADU Handbook, JADUs).
Statutory ADUs under Government Code section 66323. For these units, a local agency may not impose development or design standards that are not specifically listed in that section — and the state is explicit that this "includes, but is not limited to, parking, height, setbacks, or other zoning provisions" (ADU Handbook, 66323 Units). Parking is simply not among the standards a city may apply to them.
What to do when the counter says otherwise
State ADU law is a limit on local ordinances, and local ordinances do not always keep up with it. If your city asks for parking you believe it cannot require:
- Ask which provision of the local ADU ordinance the requirement comes from, in writing.
- Point to the specific exemption you qualify for in § 66322 — transit distance, historic district, conversion, permit parking, or car share.
- Note that a local agency also may not deny an ADU permit over the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not threaten health and safety and are not affected by the ADU's construction (§ 66322).
The California Department of Housing and Community Development publishes the handbook these rules are drawn from and reviews local ADU ordinances for compliance — hcd.ca.gov is where to look if a city's ordinance and state law appear to disagree.
