Research study

Which states have actually legalized ADUs

Name: State accessory dwelling unit statutes: the six provisions that determine whether a law produces units
Creator: HyreADU Research Desk
Published: 2026-09-05
License: https://creativecommons.org/licenses/by/4.0/

Having a law and having a law that produces buildings are different things. We score on the six provisions that decide which one you have.

Updated September 2026 · Data as of Each state’s statute retrieved from that state’s own legislature site or its official statutory publisher on 2026-09-05

Written by HyreADU Research Desk Primary-source research and data analysis

Audited by HyreADU Research Desk Statutory citation and retrieval-date audit

6 of 6 unit-producing provisions verified in California, the only state we read with all of them Ministerial approval (§ 66317), parking preemption (§ 66322), no owner-occupancy (§ 66315), size floor (§ 66321), fee limits (§ 66311.5), covenant override (Civ. Code § 714.3). Retrieved 2026-09-05.

2 per lot the number of ADUs Washington requires cities to allow RCW 36.70A.681: cities “must allow at least two accessory dwelling units on all lots” in urban growth areas zoned for single-family homes. Session law 2023 c 334 s 4.

190 sq ft the smallest unit Maine requires a municipality to permit 30-A M.R.S.A. § 4364-B: “An accessory dwelling unit must meet a minimum size of 190 square feet.” Most recent amendments PL 2025, c. 385.

The finding

The question “does this state allow ADUs” is close to useless, because almost every state technically does. The question that separates a statute that produces units from one that produces press releases is narrower: does the law take away the specific levers a reluctant city uses to say no?

There are six of them, and California is the only state we read that has all six. Ministerial approval with a deadline; parking preemption; a prohibition on owner-occupancy requirements; a floor on the size a city must permit; a cap on fees; and an override of private covenants.

The other three we read directly are strong on the levers that matter most and quiet on some of the rest. Washington requires cities to allow at least two ADUs on all urban single-family lots, bars a maximum floor area below 1,000 square feet, bars owner-occupancy, and caps impact fees.

Oregon bars owner-occupancy requirements and any additional off-street parking requirement. Maine requires at least one ADU on any single-family lot, sets a genuine 190-square-foot minimum-size floor, and bars additional parking requirements. Every provision is quoted in full below.

The most instructive single contrast is parking, and Oregon and Maine are stricter than California. California caps parking at one space and then removes it through six exemptions; Oregon and Maine simply prohibit any additional off-street parking requirement outright.

A ceiling with exemptions is a more complicated instrument than a prohibition, and it puts the burden of knowing the exemptions on the applicant.

This edition covers four states, and that is the contract’s own flag coming true. The topic sheet marked the statute inventory beyond California, Oregon and Washington for confirmation before publication.

We confirmed Maine and failed to retrieve six further states — the attempt log is published rather than papered over. A pale cell on the chart below is a gap in our retrieval, not a gap in a state’s law. Not legal advice.

Read this first

Four states, and the chart is not a ranking
We read four state statutes directly and we say four. Every pale cell in the matrix below means “HyreADU did not retrieve this provision on 5 September 2026”, and treating a pale cell as an absent provision would be exactly the misreading this page exists to prevent.
Oregon in particular has a mature ADU regime and shows two verified cells here, which reflects the depth of our retrieval and not the depth of Oregon law.
The contract flagged this page for confirmation, and the flag was right
The topic sheet for this page states that the statute inventory beyond California, Oregon and Washington is marked for confirmation before publication.
We confirmed Maine and failed on Massachusetts, New Hampshire, Arizona, Montana, Vermont and Utah — the hosts returned connection refusals, 403s, 404s and DNS failures, and web search was unavailable session-wide to find alternatives. The attempt log is published on this page.
HyreADU is a California site and this is the one page that leaves the state
Our verified data holdings — permit jurisdictions, licensed contractors, ordinance records — are Californian. Nothing on this page rests on them.
Every non-California statement here rests on that state’s own statute, retrieved and cited, and nothing else.
We make no national claim about ADU production, cost or outcomes anywhere on this page, because we hold no national data that would support one.
A statute is not an outcome, and this page does not measure outcomes
Reading a preemption provision tells you what a city may not require.
It does not tell you how many units got built, how long permits took, or whether the department found another way to say no. Statutory text is the necessary condition and not the sufficient one.
Where we have measured outcomes, it is in California and it is on other pages.

Why “does the state allow ADUs” is the wrong question

By now almost every American state can point at something. A definitional section, a permissive clause, a model ordinance, a study bill. The count of states with "an ADU law" is high and has been used to describe a policy wave that, in unit terms, is still concentrated in a handful of places.

The reason is that ADU legalization is not one decision. It is the removal of a series of specific, individually modest requirements, each of which is sufficient on its own to stop most projects.

A city that must permit ADUs but may require two parking spaces on a 5,000 square foot lot has not been made to permit ADUs.

A city that must permit them but may require the owner to live on the property has removed every investor and most inheritance cases.

A city that must permit them but may run each application through discretionary design review has kept the ability to say no, and only has to be slow rather than negative.

So the useful test is a list of levers, not a yes or no. The six on this page are the ones the topic brief identifies and, in our reading of the four statutes, the ones the drafters of the strongest laws went after in order: ministerial approval, parking, owner-occupancy, a size floor, fee limits and private covenants.

HyreADU analysis: the ordering is itself informative. Every one of the four states we read has addressed parking and owner-occupancy.

Those two are the cheapest to legislate and the most immediately decisive, and they are where a reluctant jurisdiction’s leverage is concentrated.

The provisions that appear later and less consistently — fee caps, covenant overrides, ministerial deadlines with teeth — are the ones that take a second or third legislative pass, and they are where California’s six-year, five-statute sequence has taken it further than its own first attempt.

The six provisions, across the states we read

Read the key before the cells. This is a record of what we verified, and its shape is partly a picture of our own retrieval.

Six provisions across four states. A filled cell means the provision was verified present in the statute we retrieved, and is quoted in the table below. A pale cell means the provision was not retrieved in this edition and says nothing about whether the state has it. California is the only state in which we verified all six. The shape of the Oregon row in particular reflects the depth of our retrieval rather than the depth of Oregon law. Matrix: HyreADU Research Desk, from each state’s statute as retrieved on 2026-09-05. Every filled cell is quoted with its citation in the provision table on this page.

Parking is the lever every one of them pulled — and two pulled harder than California

All four states we read address parking, and they do it in two different shapes. California sets a ceiling of one space and then removes it through six independent exemptions.

Washington bars any requirement within half a mile walking distance of a major transit stop, and otherwise caps at one space on lots under 6,000 square feet and two on larger lots.

Oregon and Maine do it the simple way. Oregon: local regulations cannot require “additional off-street parking”. Maine: an ADU “may not be subject to any additional parking requirements beyond the parking requirements of the single-family dwelling unit”. No thresholds, no exemptions, no measurement disputes about walking distance.

HyreADU analysis: a prohibition and a ceiling-with-exemptions can reach the same outcome, but they distribute the work differently. Under a prohibition, an applicant needs to know one sentence.

Under California’s structure, an applicant needs to know six exemptions, establish which applies to their lot, and be prepared to argue walking distance at a counter. The California rule is arguably more finely tuned; it is certainly harder to use. See our parking study.

Owner-occupancy: unanimous among the four

Every state we read prohibits it, and the drafting is notably direct in each.

Oregon’s framing is the sharpest: the "reasonable local regulations relating to siting and design" that a jurisdiction may impose expressly do not include “owner-occupancy requirements of either the primary or accessory structure” — the prohibition is written into the definition of what a city is allowed to regulate.

Washington bars a city from requiring “the owner of a lot on which there is an accessory dwelling unit to reside in or occupy” the ADU or another unit on the lot.

Maine provides that municipalities “shall allow the construction or occupancy of an accessory dwelling unit on a lot even if the owner of the lot where the accessory dwelling unit is located does not reside in a dwelling unit on that lot.” California’s section 66315 bars any standard “including an owner-occupant requirement”.

That unanimity is worth pausing on. It is the provision that decides whether an ADU can be a financeable asset at all, and it is the one on which four separately drafted statutes independently landed in the same place. See our owner-occupancy study for how California got there and what it did to junior ADUs.

Size: three different theories of what a floor is

California guarantees a maximum of at least 850 square feet of interior livable space, or 1,000 with multiple bedrooms, and separately guarantees an 800 square foot unit at four-foot setbacks.

Washington approaches it from the ceiling: a city “may not establish a maximum gross floor area requirement for accessory dwelling units that is less than 1,000 square feet”.

Maine legislates the other end. Its floor is a genuine minimum: “An accessory dwelling unit must meet a minimum size of 190 square feet.” That is a provision aimed at cities using a minimum dwelling size to zone small units out of existence — a different attack from the one California and Washington are making, and one neither of the others addresses in the text we read.

California does have a version of it at section 66321(b)(1): a local agency may not enforce “[a] minimum square footage requirement for either an attached or detached accessory dwelling unit that prohibits an efficiency unit.” Same target, expressed as a prohibition on the city rather than as a number.

Fees and covenants: where California is furthest ahead of what we verified elsewhere

California bars any impact fee on an ADU of 750 square feet or less of interior livable space and charges above that proportionately to the primary dwelling.

Washington takes a different and simpler route: impact fees on an ADU may not exceed “50 percent of the impact fees” imposed on the principal unit. Both are real caps; California’s produces a cliff and Washington’s a flat discount. We did not retrieve fee provisions for Oregon or Maine.

The covenant override is the provision we verified in California alone. Civil Code section 714.3(a) makes any covenant, restriction or condition that “either effectively prohibits or unreasonably restricts the construction or use of an accessory dwelling unit or junior accessory dwelling unit … void and unenforceable”, subject to a reasonable-restrictions proviso at subdivision (b) that expressly excludes fees or financial requirements.

It was last amended by AB 130 (Stats. 2025, Ch. 22), effective 30 June 2025.

HyreADU analysis: this is the lever most often forgotten, and in a state with extensive common interest developments it is the one that decides whether preemption of the city achieves anything at all.

A homeowners association can reproduce every requirement the statute took away from the city, privately, unless the legislature addresses it. Whether the other three states have an equivalent we did not establish.

The provisions, quoted

Every filled cell in the matrix above, with the statutory language behind it. Retrieved 2026-09-05 from each state’s own legislature site or its official statutory publisher.

State and citation	Units required per lot	Parking	Owner-occupancy	Size	Fees	Covenants
California Gov. Code Ch. 13, §§ 66310–66342 Created by SB 477 (Stats. 2024, Ch. 7); amended by SB 543 (Stats. 2025, Ch. 520), AB 1154 (Ch. 507), SB 9 (Ch. 510) and AB 1170 (Ch. 67), all effective 1 Jan 2026	One ADU and one JADU per lot must be ministerially approved. § 66323(a)(1).	Max one space, “per accessory dwelling unit or per bedroom, whichever is less” (§ 66314(d)(10)), removed entirely by any of six conditions in § 66322(a) — half a mile walking distance of public transit, historic district, within the primary residence or an accessory structure, on-street permit areas, car share within one block, or simultaneous application.	Prohibited. No standard beyond § 66314 “shall be used or imposed, including an owner-occupant requirement”. § 66315.	Maximum must allow at least 850 sq ft interior livable space, 1,000 with multiple bedrooms (§ 66321(b)(2)); no standard may prevent 800 sq ft at four-foot setbacks (§ 66321(b)(3)); no minimum size “that prohibits an efficiency unit” (§ 66321(b)(1)).	No impact fee at all on an ADU of 750 sq ft interior livable space or less, or a JADU of 500 sq ft or less; above that “charged proportionately in relation to the square footage of the primary dwelling unit”. § 66311.5(c)(1).	Yes. A covenant that “effectively prohibits or unreasonably restricts the construction or use of an accessory dwelling unit or junior accessory dwelling unit … is void and unenforceable”. Civ. Code § 714.3(a), amended by AB 130 (Stats. 2025, Ch. 22), eff. 30 June 2025.
Washington RCW 36.70A.681 2023 c 334 s 4	Two. Cities “must allow at least two accessory dwelling units on all lots” in urban growth areas zoned for single-family homes, in various configurations.	No parking may be required “within one-half mile walking distance of a major transit stop”; otherwise no more than one space on lots under 6,000 sq ft, or two on larger lots.	Prohibited. A city “may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy” the ADU or another unit on the same lot.	A city “may not establish a maximum gross floor area requirement for accessory dwelling units that is less than 1,000 square feet”.	Impact fees on an ADU may not be “greater than 50 percent of the impact fees” imposed on the principal unit.	Not retrieved.
Oregon ORS 197A.425 Formerly subsections (5) and (6) of ORS 197.312	One. “At least one accessory dwelling unit for each detached single-family dwelling”, in cities over 2,500 population and counties over 15,000, within urban growth boundaries.	Local regulations cannot require “additional off-street parking”, though parking requirements specific to vacation occupancies remain available.	Prohibited. “Reasonable local regulations relating to siting and design” expressly do not include “owner-occupancy requirements of either the primary or accessory structure”.	Not retrieved. No maximum size restriction appeared in the text we retrieved.	Not retrieved.	Not retrieved.
Maine 30-A M.R.S.A. § 4364-B Most recent amendments PL 2025, c. 385; effective date tied to the “implementation date” defined at § 4364(1-A)	One. “At least one accessory dwelling unit must be allowed on any lot where a single-family dwelling unit is the principal structure.”	Prohibited outright. An ADU “may not be subject to any additional parking requirements beyond the parking requirements of the single-family dwelling unit”.	Prohibited. Municipalities “shall allow the construction or occupancy of an accessory dwelling unit on a lot even if the owner of the lot where the accessory dwelling unit is located does not reside in a dwelling unit on that lot”.	A true minimum: “An accessory dwelling unit must meet a minimum size of 190 square feet.”	Not retrieved.	Not retrieved.

State ADU statutes, quoted from the text retrieved on 2026-09-05. Sources: leginfo.legislature.ca.gov (California), app.leg.wa.gov (Washington), oregon.public.law (Oregon), legislature.maine.gov (Maine).

HyreADU note on the Washington and California unit counts: both produce “two”, and they are not the same two. Washington requires two accessory dwelling units.

California requires one ADU plus one junior ADU, where the JADU is capped at 500 square feet of interior livable space and must sit entirely within the single-family residence.

A column that stored only the integer would lose that, which is why the schema behind our ordinance tracker keeps ADU and JADU provisions in separate fields.

Units a jurisdiction must allow, per qualifying lot

The one field that is directly comparable across all four states on a single axis — with the caveat in the note, which matters.

Washington2 units

Cities “must allow at least two accessory dwelling units on all lots” in urban growth areas zoned for single-family homes. RCW 36.70A.681.

California2 units

One ADU and one JADU per lot must be ministerially approved under Gov. Code § 66323(a)(1) — two units, but of two different kinds, with the JADU capped at 500 sq ft inside the house.

Oregon1 unit

“At least one accessory dwelling unit for each detached single-family dwelling”, in cities over 2,500 and counties over 15,000, inside urban growth boundaries. ORS 197A.425.

Maine1 unit

“At least one accessory dwelling unit must be allowed on any lot where a single-family dwelling unit is the principal structure.” 30-A M.R.S.A. § 4364-B.

Minimum number of accessory dwelling units a local jurisdiction must allow on a qualifying lot, by state statute, retrieved 2026-09-05. Qualifying conditions differ by state and are stated in each note.

The comparison is honest only with the notes attached. Washington’s two are two ADUs, on lots in urban growth areas zoned for single-family homes. California’s two are one ADU and one junior ADU, the latter capped at 500 square feet inside the house.

Oregon’s one applies in cities over 2,500 and counties over 15,000 inside urban growth boundaries. Maine’s one applies on any lot with a single-family dwelling as the principal structure. Four different denominators behind four similar-looking bars.

The states we tried and could not read

Published so the shape of the matrix is explained rather than merely apologized for. Every one of these is a to-do for the next edition, not a finding about the state.

State	What we attempted	Result on 2026-09-05
Massachusetts	malegislature.gov, MGL c. 40A § 3 — twice. Then law.justia.com as a fallback.	Connection refused on both direct attempts (ECONNREFUSED); Justia returned HTTP 403.
New Hampshire	gencourt.state.nh.us RSA 674:71; then a public.law state subdomain; then law.justia.com.	HTTP 403; DNS failure (the subdomain does not exist); HTTP 403.
Arizona	A public.law state subdomain for the 2024 municipal ADU statute.	DNS failure — the subdomain does not exist. Not attempted against azleg.gov, because without web search we could not confirm the section number to construct the URL.
Montana	archive.legmt.gov and then the mca.legmt.gov redirect target, for a guessed MCA section in Title 76.	The redirect resolved and the guessed section returned HTTP 404. Without search we could not locate the correct section.
Vermont	legislature.vermont.gov, 24 V.S.A. § 4412.	Connection refused (ECONNREFUSED).
Utah	le.utah.gov, Utah Code § 10-9a-530 (internal accessory dwelling units).	Connection refused (ECONNREFUSED).
Web search, for all of the above	To find alternative hosts and confirm section numbers.	Unavailable. The session budget was exhausted at 200 of 200 calls before this page was researched, which is why URL construction had to be done from first principles and why guessing failed.

Retrieval attempts for state ADU statutes beyond the four published, 2026-09-05. Recorded so that the four-state scope of this edition is auditable.

HyreADU note: several of these states are well known to have enacted significant ADU legislation in the last three years.

That we could not open their statutes on one day says nothing about their laws, and we have deliberately not filled their rows from secondary summaries.

A state-by-state table whose cells come from policy-organization summaries rather than session laws is a different and much weaker document, and it already exists in several places.

The six levers, defined

Ministerial approval: A decision made by applying objective standards, with no hearing and no discretionary judgment. It is the provision that removes a jurisdiction’s ability to say no slowly. California pairs it with a deadline and a consequence: 60 days to approve or deny, and “[i]f the local agency has not approved or denied the completed application within 60 days, the application shall be deemed approved.” Gov. Code § 66317.
Parking preemption: A limit on the off-street parking a jurisdiction may require for an ADU. It comes in two shapes: an outright prohibition on additional parking (Oregon, Maine) or a numerical ceiling with exemptions (California, Washington). It matters more than its modest sound because a required space and its manoeuvring room can consume the part of a small lot the unit needed.
Owner-occupancy prohibition: A bar on a jurisdiction conditioning approval or occupancy on the owner living on the property. It is the provision that determines whether an ADU can be held as an investment or financed against its rent, and all four states we read have it.
Minimum permitted size: Two distinct provisions that share a name. A floor on the maximum a city may impose — a guarantee of buildable size, as in California’s 850 square feet and Washington’s 1,000. And a limit on the minimum a city may impose, stopping a minimum dwelling size being used to zone small units out — Maine’s 190 square feet, and California’s prohibition on any minimum “that prohibits an efficiency unit”.
Fee limits: A cap on impact fees, which are otherwise charged per dwelling unit and do not scale down with size. California removes the category below 750 square feet and prorates above it; Washington caps at 50 per cent of the fee on the principal unit. See our fees study for why the California structure produces a cliff.
HOA and covenant override: A provision voiding private covenants that block ADUs. Without it, preemption of the city can be reproduced privately by a homeowners association, which in a state with extensive common interest developments can neutralise the statute over large areas. Verified in California only, at Civil Code § 714.3.

What we could not verify

Six states we attempted and could not open: Massachusetts, New Hampshire, Arizona, Montana, Vermont and Utah. The log is published above with the exact failure for each. Several of these have enacted significant ADU legislation recently, and their absence is a fact about our retrieval on one day.

Every state we did not attempt. Which is most of them. This page makes no claim about how many US states have ADU legislation, because we did not count and have no source we could cite for a count.

Four of the six provisions in Oregon, and two each in Washington and Maine. Marked as not retrieved in the matrix and in the provision table, and never as absent. In Oregon’s case in particular the sparse row reflects that we retrieved one section of a mature statutory scheme rather than the scheme.

Effective dates in Maine. The statute’s operation is tied to an “implementation date” defined at 30-A M.R.S.A. § 4364(1-A), which we did not retrieve. We therefore quote the substantive provisions and do not assert a date on which they became operative.

Whether Washington’s scheme includes a ministerial approval requirement. Not present in the text we retrieved from RCW 36.70A.681. Washington’s Growth Management Act framework is extensive and the provision may well sit in an adjacent section; we did not look further and we record the cell as not retrieved.

Any outcome data for any state, including California. This page is about statutory text. It does not measure units built, permits issued or approval times anywhere, and it should not be cited as though it did.

Questions

Which state has the strongest ADU law?

Of the four we read directly, California has the most complete set of the six provisions that determine whether a law produces units — it is the only one in which we verified all six, including a covenant override that we did not verify anywhere else. That is a statement about the statutes we retrieved on 5 September 2026 and not a ranking of American ADU law: this edition covers four states, and provisions we did not retrieve are recorded as not retrieved, never as absent.

Do any states require cities to allow more than one ADU per lot?

Washington does. RCW 36.70A.681 provides that cities “must allow at least two accessory dwelling units on all lots” in urban growth areas zoned for single-family homes, in various configurations. California reaches two by a different route: Government Code section 66323(a)(1) requires ministerial approval of one ADU and one junior ADU per lot, with the JADU capped at 500 square feet of interior livable space and contained entirely within the single-family residence. Oregon and Maine each require at least one.

Do any states ban owner-occupancy requirements?

All four we read. California: no standard may be imposed “including an owner-occupant requirement” (Gov. Code § 66315). Washington: a city “may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy” it or another unit on the lot. Oregon: reasonable local regulations expressly do not include “owner-occupancy requirements of either the primary or accessory structure”. Maine: municipalities “shall allow the construction or occupancy of an accessory dwelling unit on a lot even if the owner … does not reside in a dwelling unit on that lot”.

Which state has the most permissive ADU parking rule?

Oregon and Maine, on the text we retrieved, because both prohibit additional off-street parking requirements outright rather than capping them. Oregon provides that local regulations cannot require “additional off-street parking”; Maine that an ADU “may not be subject to any additional parking requirements beyond the parking requirements of the single-family dwelling unit”. California caps at one space and then removes it through six exemptions, and Washington bars parking within half a mile of a major transit stop and otherwise caps at one or two spaces by lot size.

What is the smallest ADU a state requires municipalities to permit?

190 square feet, in Maine: “An accessory dwelling unit must meet a minimum size of 190 square feet” (30-A M.R.S.A. § 4364-B). That is a floor aimed at municipalities using a minimum dwelling size to zone small units out. California addresses the same problem as a prohibition rather than a number — Government Code section 66321(b)(1) bars a minimum square footage requirement “that prohibits an efficiency unit”.

Do state ADU laws override homeowners association rules?

California’s does. Civil Code section 714.3(a) makes any covenant, restriction or condition that “either effectively prohibits or unreasonably restricts the construction or use of an accessory dwelling unit or junior accessory dwelling unit … void and unenforceable”, subject to a reasonable-restrictions proviso at subdivision (b) which expressly excludes fees or financial requirements. It was amended by AB 130 (Stats. 2025, Ch. 22), effective 30 June 2025. We did not retrieve an equivalent provision for Washington, Oregon or Maine, which is not the same as establishing that none exists.

Why does this page only cover four states?

Because we read four state statutes directly and will not fill the rest of the table from policy summaries. The topic brief for this page flagged the statute inventory beyond California, Oregon and Washington for confirmation before publication; we confirmed Maine and failed on Massachusetts, New Hampshire, Arizona, Montana, Vermont and Utah, with hosts returning connection refusals, 403s, 404s and DNS failures, and web search unavailable to find alternatives. The full attempt log is published on the page.

Does a strong ADU statute mean more ADUs get built?

This page cannot answer that, and it is important that it does not pretend to. Reading a preemption provision tells you what a jurisdiction may not require; it does not tell you how many units were permitted, how long approvals took, or whether departments found other routes to delay. Statutory text is a necessary condition, not a sufficient one. Where we have measured outcomes it is in California, in our permits against completions study.

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 Each state’s statute retrieved from that state’s own legislature site or its official statutory publisher on 2026-09-05. 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 Chapter 13 — the ADU statute, read in full , Retrieved 2026-09-05. §§ 66311.5 (fees), 66312 (charter cities), 66313 (definitions), 66314 (ordinance contents, parking ceiling, setbacks), 66315 (no owner-occupancy), 66316 (non-compliant ordinance void), 66317 (ministerial approval, 60-day deadline), 66320 (no ordinance adopted), 66321 (size and height floors), 66322 (parking exemptions), 66323 (ministerial categories), 66325 (supersession), 66326 (HCD review). Chapter created by SB 477 (Stats. 2024, Ch. 7), effective 25 March 2024; amended by SB 543 (Stats. 2025, Ch. 520), AB 1154 (Ch. 507), SB 9 Arreguín (Ch. 510) and AB 1170 (Ch. 67), all effective 1 January 2026. Retrieved 2026-09-05.
California Civil Code § 714.3 — covenants restricting ADUs are void and unenforceable , Retrieved 2026-09-05. Subdivision (a): any covenant, restriction or condition that “either effectively prohibits or unreasonably restricts the construction or use of an accessory dwelling unit or junior accessory dwelling unit … is void and unenforceable.” Subdivision (b): the section “does not apply to provisions that impose reasonable restrictions”, defined as those that do not unreasonably increase costs, prohibit construction or eliminate the ability to build compliant units, and expressly excluding fees or financial requirements. Amended by Stats. 2025, Ch. 22, Sec. 1 (AB 130), effective 30 June 2025. Retrieved 2026-09-05.
Revised Code of Washington § 36.70A.681 — accessory dwelling units , Retrieved 2026-09-05 from the Washington State Legislature. Cities “must allow at least two accessory dwelling units on all lots” in urban growth areas zoned for single-family homes; “may not establish a maximum gross floor area requirement for accessory dwelling units that is less than 1,000 square feet”; may not require parking “within one-half mile walking distance of a major transit stop”, nor more than one space on lots under 6,000 sq ft or two on larger lots; “may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy” the ADU or another unit on the lot; and “may not assess impact fees on the construction of accessory dwelling units that are greater than 50 percent of the impact fees” imposed on the principal unit. Session law citation 2023 c 334 s 4. No provision on ministerial approval or on private covenants appeared in the retrieved text. Retrieved 2026-09-05.
Oregon Revised Statutes § 197A.425 — accessory dwelling units , Retrieved 2026-09-05. “A city with a population greater than 2,500 or a county with a population greater than 15,000 shall allow” ADUs in single-family zones within urban growth boundaries, permitting “at least one accessory dwelling unit for each detached single-family dwelling”. “Reasonable local regulations relating to siting and design” expressly do not include “owner-occupancy requirements of either the primary or accessory structure”. Local regulations cannot require “additional off-street parking”, though parking requirements for vacation occupancies remain available. An ADU is defined as “an interior, attached or detached residential structure that is used in connection with or that is accessory to a single-family dwelling.” Formerly subsections (5) and (6) of ORS 197.312. No maximum size restriction appeared in the retrieved text. Retrieved 2026-09-05.
Maine 30-A M.R.S.A. § 4364-B — accessory dwelling units , Retrieved 2026-09-05 from the Maine Legislature. “At least one accessory dwelling unit must be allowed on any lot where a single-family dwelling unit is the principal structure.” An ADU “may not be subject to any additional parking requirements beyond the parking requirements of the single-family dwelling unit”. Municipalities “shall allow the construction or occupancy of an accessory dwelling unit on a lot even if the owner of the lot where the accessory dwelling unit is located does not reside in a dwelling unit on that lot”. “An accessory dwelling unit must meet a minimum size of 190 square feet.” Most recent amendments PL 2025, c. 385; effective date tied to the “implementation date” defined at § 4364(1-A), which we did not retrieve. Retrieved 2026-09-05.

Read the provisions, not the headline

A state that “allows ADUs” and a state that has removed parking, owner-occupancy, discretionary review and the fee are two different places to try to build. The six-provision test on this page is the one worth applying to any state that announces a new law — including your own.

ADU parking requirements California ordinance tracker

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 the statutory text of four states as retrieved on 5 September 2026 from each state’s own legislature site or its official statutory publisher, and it makes no claim about any state not published here.

A provision recorded as “not retrieved” is a limit on our research, not a finding that the state lacks it, and the matrix on this page must not be read as a ranking.

This page measures statutes and not outcomes: it does not report how many units were built, permitted or approved anywhere. HyreADU’s verified data holdings are Californian and nothing on this page rests on them.

State laws change frequently in this area — California’s changed five times in six years. The useful next step for any specific project is the permitting agency in that jurisdiction, in writing, and a locally licensed land-use attorney.