Research study
ADU parking and the half-mile transit rule
The maximum is one space whatever the bedroom count, six separate conditions reduce it to zero, and the widest of them turns on how the statute defines a bus stop.
Written by HyreADU Research Desk Primary-source research and data analysis
Audited by HyreADU Research Desk Statutory citation and retrieval-date audit
The finding
The most a California city may require for an accessory dwelling unit is one off-street parking space, and a four-bedroom unit faces the same maximum as a studio. Government Code section 66314(d)(10) sets the standard as “One parking space per accessory dwelling unit or per bedroom, whichever is less.” The “whichever is less” clause caps it at the unit, so there is no per-bedroom escalation.
Six separate conditions take that one space to zero, and any one of them is enough. Section 66322 applies “[n]otwithstanding any other law, and whether or not the local agency has adopted an ordinance governing accessory dwelling units”, and the six are set out provision by provision below: transit proximity, a historic district, conversion of existing space, unavailable on-street permits, a car share vehicle within one block, and filing together with a new dwelling.
The transit exemption is wide because of the definition, not the distance. Section 66313(m) defines public transit to include a bus stop, so half a mile of walking distance from any bus stop covers a very large share of urban and suburban California.
A demolished garage does not have to be replaced. Section 66314(d)(11) provides that where a garage, carport or covered parking structure is demolished or converted to build the ADU, the local agency “shall not require that those offstreet parking spaces be replaced.” This page publishes no statewide transit buffer, because the feed data available to us will not support one honestly.
The reasons are set out in full further down. Not legal advice.
Read this first
- We did not build the transit buffer, and this page publishes no coverage percentage
The contract for this page anticipated intersecting a half-mile buffer built from agency GTFS stop data with each jurisdiction’s parking provision, in order to establish where the exemption actually reaches.
We attempted the data layer and it is not there — see the section below.
Nowhere on this page will you find a figure for what share of California lots fall within the exemption, because we did not measure it, and a buffer built on an incomplete feed would understate the exemption in exactly the direction that hurts an applicant.
- This is not legal advice, and “walking distance” is a measurement with an argument in it
The statute says “one-half of one mile walking distance”, which is a network distance along walkable routes, not a straight line on a map.
Where the measurement is contested — a freeway between the lot and the stop, a gated path, a crossing that exists but is not signalised — it is resolved by the permitting agency, and ultimately by lawyers.
This page sets out the statutory text and does not measure any parcel.
- A local ordinance may be more permissive, and many are
Section 66314(b)(2) expressly allows local agencies to reduce or eliminate parking requirements, and Government Code section 66325(b) preserves local authority “to adopt less restrictive requirements”. Everything on this page is a ceiling on what a city may impose. A city that requires no ADU parking at all is complying, not deviating.
- The exemptions are alternatives, not a test you have to pass in full
The most common misreading we encountered is treating section 66322(a) as a set of cumulative conditions. It is a list of alternatives.
A unit inside the existing house qualifies under (a)(3) whether or not there is a bus stop anywhere near it.
A unit half a mile from a bus stop qualifies under (a)(1) whether or not it is detached.
Why parking, of all things, decides so many ADU projects
A parking space is not a small imposition on a small lot.
A compliant space plus the manoeuvring room to reach it consumes a meaningful share of a typical California back garden, and it usually has to come out of exactly the part of the lot the unit itself wants.
On a 5,000 square foot lot with a house already on it, a required space can be the difference between a buildable 800 square foot unit and no unit.
It also sits at the intersection of the two things that make ADU permitting hard: a design standard that is easy for a city to state and expensive for an applicant to satisfy, and a preemption question that most applicants do not know they are allowed to raise.
Section 66322 is unusually generous by the standards of California land use law, and unusually little used, because an applicant who does not know it exists will simply build the space.
HyreADU analysis: the structural reason the exemption reaches so far is not the half mile. Half a mile is a conventional distance and appears in Washington and Massachusetts law too. It is the definition.
Section 66313(m) defines public transit as “a location, including, but not limited to, a bus stop or train station” — an inclusive definition anchored on a bus stop, which is the most common transit facility in existence and the one that is nearly everywhere in an incorporated California city.
The drafting choice that did the work was made in the definitions section, not in the parking section.
The parking rule, provision by provision
Everything a California city may and may not do about ADU parking, in four provisions. Quoted as retrieved on 2026-09-05.
| Provision | What it establishes | Operative text as retrieved | Currency |
|---|---|---|---|
| Gov. Code § 66314(b)(2) | Cities may go below the state standard. | Local agencies may reduce or eliminate parking requirements for accessory dwelling units. | Amended by Stats. 2025, Ch. 67, Sec. 109 (AB 1170), effective 1 January 2026. |
| Gov. Code § 66314(d)(10) | The ceiling, and it does not scale with bedrooms. | “One parking space per accessory dwelling unit or per bedroom, whichever is less.” | Same section and amendment. |
| Gov. Code § 66314(d)(11) | A demolished garage does not have to be replaced. | Where a garage, carport or covered parking structure is demolished or converted in conjunction with the construction of an ADU, the local agency shall not require that those off-street parking spaces be replaced. | Same section and amendment. |
| Gov. Code § 66322 | The six exemptions, which apply whether or not the city has an ADU ordinance at all. | Opening: “Notwithstanding any other law, and whether or not the local agency has adopted an ordinance governing accessory dwelling units …”. Then (a)(1) “Where the accessory dwelling unit is located within one-half of one mile walking distance of public transit.” (a)(2) “Where the accessory dwelling unit is located within an architecturally and historically significant historic district.” (a)(3) “Where the accessory dwelling unit is part of the proposed or existing primary residence or an accessory structure.” (a)(4) “When on-street parking permits are required but not offered to the occupant of the accessory dwelling unit.” (a)(5) “When there is a car share vehicle located within one block of the accessory dwelling unit.” (a)(6) applications submitted simultaneously for an ADU with a new single-family or multifamily dwelling. Subdivision (b) separately bars denial for correcting nonconforming zoning or building code violations that do not threaten public health and safety. | Added by Stats. 2024, Ch. 7, Sec. 20 (SB 477), effective 25 March 2024. Not renumbered by SB 543. |
| Gov. Code § 66313(m) | The definition that makes (a)(1) reach so far. | Public transit means “a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation.” | Amended by Stats. 2025, Ch. 520, Sec. 2 (SB 543), effective 1 January 2026. |
| Gov. Code § 66313(n) | Tandem parking is available where a space is required at all. | Tandem parking means “two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.” | Same section and amendment. |
The California statutory framework for accessory dwelling unit parking. Source: California Government Code, retrieved from leginfo.legislature.ca.gov on 2026-09-05.
HyreADU note on citation: section 66322 was created by the March 2024 recodification and, unlike much of Chapter 13, was not touched by the second renumbering in SB 543. Any source citing former Government Code section 65852.2(d) for the parking exemptions is describing the same five exemptions under a section repealed in March 2024.
One space, six ways to zero
The structure of the rule, drawn. Read the diagram as six alternative doors out of the same room, not as a corridor you have to walk the length of.
(a)(1) — half a mile from public transit, and the definition is the point
The widest of the six, and the reason is section 66313(m): public transit is “a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation.” An ordinary bus stop on an ordinary route qualifies.
Measure it as walking distance. The statute says “one-half of one mile walking distance”, not radius.
In practice that is a route along the pedestrian network, which can be materially longer than the straight-line distance where a freeway, a rail corridor, a watercourse or a gated development sits between the lot and the stop.
Where the two measures disagree, the network measure is the one the statute names.
(a)(3) — inside the house or an accessory structure, with no geography at all
The exemption most often overlooked, and the one that requires nothing of the neighborhood.
A conversion of interior space, a garage conversion or a unit within an existing accessory structure qualifies on its own facts, wherever the lot is.
A rural lot ten miles from the nearest bus route is exempt under (a)(3) if the unit is inside the existing building envelope.
Combine it with § 66314(d)(11) and the garage-conversion case becomes unusually clean: the conversion is exempt from any parking requirement, and the spaces the garage used to provide need not be replaced. Our garage conversion comparison is where that trade-off is worked through.
(a)(4) and (a)(5) — the two nobody uses
Where on-street parking permits are required in the area but are not offered to the ADU’s occupant, no parking may be required. And where a car share vehicle is located within one block, no parking may be required.
HyreADU analysis: these are narrow but they are real, and both are questions of fact that an applicant can establish with a photograph and a permit-scheme document.
The car share condition in particular is checkable in a minute in most dense California neighborhoods, and we have seen it invoked almost nowhere.
Where an applicant is close to but not inside the half-mile buffer, these two are worth checking before conceding the space.
(a)(2) and (a)(6) — the historic district, and the simultaneous application
A unit within an architecturally and historically significant historic district is exempt from parking. That is a striking inversion of the usual pattern, in which a historic district adds constraints rather than removing them — here the constraint on the streetscape works in the applicant’s favor.
Subdivision (a)(6) addresses applications submitted simultaneously for an ADU together with a new single-family or multifamily dwelling. This one is a sequencing point: the same project can land differently depending on whether the ADU is filed with the house or after it.
The buffer we could not build, and why the flag was right
The contract for this page carried an explicit instruction: statewide GTFS coverage is marked for confirmation before publication, because a buffer built on an incomplete feed would understate the exemption. We attempted the confirmation. The flag was correct and the answer is negative.
Fact, retrieved 2026-09-05: the GTFS repository operated by Caltrans at gtfs.dds.dot.ca.gov lists 25 active transit service feeds, plus three test datasets for developers. The agencies represented are predominantly small and specialty operators.
Most entries carry an upload date of 24 October 2022; the oldest is from January 2022, and only three entries are more recent than 2022. The feeds are published under a Creative Commons Attribution 4.0 license.
HyreADU analysis: California has on the order of two hundred public transit operators. A repository of twenty-five feeds, weighted toward small operators and largely frozen in 2022, is not a basis for a statewide stop layer.
Building a half-mile buffer from it would produce a map that is confidently wrong: it would show exemption coverage clustered around a handful of small agencies and absent across the large metropolitan operators, which is close to the inverse of the truth.
The failure mode is asymmetric and it hurts applicants — a missing stop reads as “no exemption here”, and an applicant who believed such a map would build a parking space they were entitled not to build.
So this page publishes no buffer, no map and no coverage percentage. The honest statement of what the exemption reaches is qualitative: the statute anchors on a bus stop, and bus stops are dense in incorporated California, so the exemption reaches very widely in urban and suburban areas and thins in rural ones.
We are not going to convert that into a number we did not measure.
What a real version of this analysis needs. Stop-level data from the large operators directly rather than from an aggregator — Los Angeles Metro, SFMTA, AC Transit, VTA, SANDAG’s operators, OCTA, Sacramento RT and the rest — plus a walking network rather than a Euclidean radius, because the statute says walking distance.
That is a substantial data engineering exercise and it is the right next edition of this page. It is not something to approximate.
Establishing the exemption for your own lot
In this order, and stop as soon as one of them lands — they are alternatives.
- 1 Ask first whether the unit is inside the existing envelope
Section 66322(a)(3) exempts an ADU that “is part of the proposed or existing primary residence or an accessory structure.” This requires nothing of the neighborhood and no measurement. If the project is a conversion, the parking question is very likely already answered, and it is answered before you look at a map.
- 2 Measure the walking distance to the nearest transit stop, not the radius
Half a mile, along the pedestrian network. Use the agency’s own published stop location rather than a third-party map layer, and record the route you measured.
Where the straight-line distance is under half a mile and the walking route is over it, expect the question to be contested, and have the route documented before the conversation rather than after.
- 3 Check the two nobody checks
Is there a residential parking permit scheme on the street, and would the ADU occupant be excluded from it? Is there a car share vehicle within one block? Either is sufficient on its own under (a)(4) or (a)(5), and both are cheap to establish with documentation and a photograph.
- 4 Check whether your lot is in a historic district
Section 66322(a)(2) exempts a unit within an architecturally and historically significant historic district. If the district designation is otherwise adding cost to your project through design review, this is the one place it pays you back.
- 5 If a garage is coming down, invoke § 66314(d)(11) explicitly
The no-replacement rule for demolished or converted covered parking is separate from the exemptions in section 66322 and is easy for a plan checker to miss on a project that removes a garage. Cite it on the application rather than waiting to be asked.
- 6 Put the conclusion to the permitting agency in writing, with the citation
Ask which parking standard the agency will apply given sections 66314(d)(10) and 66322, and state which exemption you are relying on and why.
Section 66322 applies “whether or not the local agency has adopted an ordinance”, so the answer does not depend on the local code — but the person at the counter may be reading the local code, and a written question produces a written answer.
The four terms that decide it
- Public transit
- “A location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation.” Gov. Code § 66313(m). The inclusive framing and the express naming of a bus stop are what make the half-mile exemption reach as far as it does. Contrast Washington’s narrower anchor on a “major transit stop”.
- Walking distance
- Not defined in the ADU chapter, and the source of most disputes about the transit exemption. The statutory phrase is “one-half of one mile walking distance”, which on its face is a network distance along walkable routes rather than a radius. Where the two measures disagree, document the route.
- Tandem parking
- “Two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.” Gov. Code § 66313(n). Relevant where a space is required at all: a tandem arrangement on an existing driveway will often satisfy the requirement without consuming new ground.
- Nonconforming zoning condition
- “A physical improvement on a property that does not conform to current zoning standards.” Gov. Code § 66313(h). Relevant because § 66322(b) separately bars a local agency from denying an ADU permit for the correction of nonconforming zoning conditions or building code violations that do not threaten public health and safety — an existing non-compliant driveway is not a ground for refusal.
What we could not verify
Any transit buffer, and therefore any coverage figure. Named above and named again here because it is the largest gap and the one the contract anticipated. We publish no map and no percentage.
The full text of § 66314. We retrieved the section and quoted its parking provisions, but the retrieval returned subdivisions (e) and (f) — on garage demolition permits and placard requirements — only in summary. Nothing on this page rests on those subdivisions, and we have not quoted them.
How any individual jurisdiction words its parking provision. Codified municipal text could not be retrieved for this edition: the platform hosting most California municipal codes returned HTTP 403 to every automated request, and web search was unavailable.
Since section 66322 applies whether or not a city has an ordinance, the state analysis stands on its own — but a per-city column showing which ordinances have been amended to match remains unbuilt. See the ordinance tracker.
Whether any published interpretation of “walking distance” exists. This is the point on which the transit exemption is most likely to be litigated or argued at a counter, and we found no authority defining it in this context. HCD would be the natural source; hcd.ca.gov returned HTTP 403 and a scheduled-maintenance notice throughout this retrieval.
State statutes beyond the four in the chart. We retrieved California, Oregon, Washington and Maine directly from official or official-publisher sources. Other states are absent from this page rather than shown as having no rule.
Questions
Do I need to provide parking for an ADU in California?
Does a bus stop count as public transit for the half-mile rule?
Is it half a mile as the crow flies or half a mile of walking?
Do I need more parking for a three-bedroom ADU than a studio?
If I convert my garage, do I have to replace the parking spaces it provided?
What if my city’s code still requires ADU parking?
How much of California is within half a mile of transit?
Which state has the most permissive ADU parking rule?
Written and audited by
HyreADU Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a builder. We read the permit extract, the statute, the HCD return or the fee schedule ourselves, and publish each figure with its source and retrieval date.
Where a number cannot be traced to a primary source, we leave it out and say what we could not verify. Our store-based claims cover California only.
- CA
- the only state this desk will make store-based claims about
- 5
- jurisdictions with extracted ADU permit evidence
- 735
- CSLB-verified companies in the California store
- 0
- national claims from a one-state store
How this desk works
- Primary sources only. Permit counts come from the city or county that issued the permit. Production counts come from HCD’s Annual Progress Report. Rents come from HUD or the Census. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
- This is a California site. The company store is 734 California firms and one New Mexico firm. Permit evidence exists for five named jurisdictions: Los Angeles, San Francisco, Sacramento, San José and unincorporated Marin. A number from that store is titled to those places, never to the United States.
- A permit is not a completion, and a license is not an ADU grade. California licenses no ADU classification. Being named on an ADU permit is evidence of engagement in that jurisdiction, not of quality, completion, or work anywhere else. Owner-builder permits are excluded from contractor counts.
- Calculation is labeled as calculation. Figures we derive are never presented as something HCD, HUD, the Census or a city published. Terner Center research is cited as Terner’s, never restated as ours.
- We do not design, permit or build ADUs, and we take no payment for placement, ranking or a favorable mention. Pages that look like rankings are not: they publish public-record counts and let the reader decide.
- Nothing here is legal, tax or financial advice. Zoning, underwriting and appraisal practice vary by jurisdiction, lender and appraiser. The useful next step on a specific lot is the planning counter and a licensed professional.
Data as of Government Code §§ 66313, 66314 and 66322 retrieved from leginfo.legislature.ca.gov 2026-09-05; Caltrans GTFS repository inventory retrieved 2026-09-05; other-state statutes retrieved from each state’s own or official publisher on the same date. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold.
Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
- California Government Code § 66322 — the six ADU parking exemptions , Retrieved 2026-09-05. Opening: “Notwithstanding any other law, and whether or not the local agency has adopted an ordinance governing accessory dwelling units …”. (a)(1) “Where the accessory dwelling unit is located within one-half of one mile walking distance of public transit.” (a)(2) historic district. (a)(3) “Where the accessory dwelling unit is part of the proposed or existing primary residence or an accessory structure.” (a)(4) “When on-street parking permits are required but not offered to the occupant of the accessory dwelling unit.” (a)(5) “When there is a car share vehicle located within one block of the accessory dwelling unit.” (a)(6) simultaneous applications with a new single-family or multifamily dwelling. (b) bars denial for correcting nonconforming zoning or building code violations not threatening public health and safety. Enactment line: “Added by Stats. 2024, Ch. 7, Sec. 20. (SB 477) Effective March 25, 2024.” Retrieved 2026-09-05.
- California Government Code § 66314 — objective standards, the one-space cap and the no-replacement rule , Retrieved 2026-09-05. (b)(1) local agencies impose objective standards “that include, but are not limited to, parking, height, setback, landscape, architectural review, maximum size of a unit”; (b)(2) local agencies may reduce or eliminate parking requirements; (d)(10) “One parking space per accessory dwelling unit or per bedroom, whichever is less”; (d)(11) demolished or converted covered parking need not be replaced; (d)(5) “Detached accessory dwelling unit shall not exceed 1,200 square feet”; (d)(7) “Setback of no more than four feet from the side and rear lot lines”. Enactment line: “Amended by Stats. 2025, Ch. 67, Sec. 109. (AB 1170) Effective January 1, 2026.” Retrieved 2026-09-05.
- California Government Code § 66313 — definitions of public transit and tandem parking , Retrieved 2026-09-05. Subdivision (m): public transit is “a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation.” Subdivision (n): tandem parking means “two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.” Subdivision (h): a nonconforming zoning condition is “a physical improvement on a property that does not conform to current zoning standards.” Amended by Stats. 2025, Ch. 520, Sec. 2 (SB 543), effective 1 January 2026. Retrieved 2026-09-05.
- Caltrans GTFS data repository — the inventory that stopped this analysis , Retrieved 2026-09-05. A California Department of Transportation GTFS repository. The listing presents 25 active transit service feeds plus 3 test datasets for developers, predominantly small and specialty operators, with feeds hosted under agency-specific filenames at /gtfs_files/. Most entries carry an upload date of 24 October 2022; the oldest is 13 January 2022 and only three entries are later than 2022. Data is licensed under Creative Commons Attribution 4.0 International. Cited as the evidence for why no statewide transit buffer is published on this page. Retrieved 2026-09-05.
- Revised Code of Washington § 36.70A.681 — Washington ADU parking preemption , Retrieved 2026-09-05. Cities may not require parking “within one-half mile walking distance of a major transit stop”, nor more than one space per unit on lots under 6,000 square feet or two spaces on larger lots. Session law citation 2023 c 334 s 4. Cited for the cross-state comparison. Retrieved 2026-09-05.
- Oregon Revised Statutes § 197A.425 — Oregon ADU parking , Retrieved 2026-09-05. Local regulations cannot require “additional off-street parking” for an accessory dwelling unit, though governments may impose parking requirements specifically for vacation occupancies. Formerly subsections (5) and (6) of ORS 197.312. Cited for the cross-state comparison. Retrieved 2026-09-05.
- Maine 30-A M.R.S.A. § 4364-B — Maine ADU parking , Retrieved 2026-09-05. An accessory dwelling unit “may not be subject to any additional parking requirements beyond the parking requirements of the single-family dwelling unit”. Most recent amendments PL 2025, c. 385. Cited for the cross-state comparison. Retrieved 2026-09-05.
Check the exemption before you draw the space
Six independent conditions each take the requirement to zero, and a conversion inside the existing envelope qualifies without reference to a map at all. Find out which one applies to your lot before you give up the square footage — the envelope calculator will show you what that space was costing.
HyreADU does not design, permit or build accessory dwelling units and does not practice law. This page is informational and is not legal advice.
It describes California statutory text as retrieved on 5 September 2026 and does not measure any parcel, any walking route or any transit stop.
It deliberately publishes no transit buffer, map or coverage figure, because the statewide feed data required to build one honestly is not available — a limitation stated in full on the page rather than worked around.
Whether an exemption applies to a particular lot is determined by the permitting agency on the facts, and “walking distance” is a measurement on which reasonable people disagree.
The useful next step is the permitting agency, in writing, citing the sections by number.