A growing number of states now require cities to allow accessory dwelling units. Here's which states have statewide ADU laws — and which leave it to local zoning.
ADUs are legal in all 50 states — the real question is whether your state forces local governments to allow them. As of 2026, at least 11 states have passed statewide laws requiring cities to permit ADUs by-right or ministerially (led by California, Oregon, Washington, and most of New England). In the remaining states, local zoning decides — so whether you can build depends on your specific city or county. The table below shows where each state stands; click a state for city-by-city rules.
| State | Statewide ADU Law? | Key Statute | What It Does |
|---|---|---|---|
| Maryland | Yes — statewide mandate (local laws due 1 Oct 2026) | HB 1466 (2025) / Ch. 197, Land Use §§ 4-501–4-504 | Every county and municipal legislative body must adopt a local law authorising ADUs on single-family-detached lots on or before 1 October 2026 (§ 4-504(a)). The Act caps an ADU at 75% of the size of the primary dwelling (§ 4-501(b)), excludes ADUs from density limits, caps side/rear setbacks at the accessory-structure setback and allows parking rules only after a parking study (§ 4-504(c)-(e)). The 90-day-review, impact-fee and utility clauses were struck before passage; §§ 4-505 to 4-507 do not exist. Covenants barring ADUs are void (Real Prop. § 2-126). |
| California | Yes — statewide mandate | Gov. Code §§66310–66342 (SB 543, AB 1154, SB 9 — Jan 2026) | Ministerial approval within 60 days of a complete application, deemed approved if the city does not act (§66317(a)(3), SB 543, Jan 1, 2026); local size caps may not fall below 850 sq ft, or 1,000 sq ft for 2+ bedrooms (§66321(b)(2)), and a detached ADU ordinance cap may not exceed 1,200 sq ft (§66314(d)(5)); side/rear setbacks no more than 4 ft (§66314(d)(7)); no parking within ½ mile of public transit or for conversions (§66322); no owner-occupancy for ADUs (§66315); impact fees waived for units of 750 sq ft of interior livable space or less (§66311.5(c)(1)). |
| Oregon | Yes — cities over 2,500 / counties over 15,000 | ORS 197A.425 (SB 1051, 2017; HB 2001, 2019; renumbered from ORS 197.312(5)–(6)) | Cities over 2,500 and counties over 15,000 must allow at least one ADU for each detached single-family home in single-family zones inside the urban growth boundary; the 'reasonable siting and design' rules they may impose cannot include owner-occupancy or extra off-street parking (ORS 197A.425(1)); vacation-rental use may still be regulated (197A.425(2)). No state size cap, unit count above one, or fee waiver — those are local. HB 2138 (2025) limits private CC&Rs from Jan 1, 2027 and directs LCDC rules on ADU siting/design standards by Jan 1, 2028. |
| Washington | Yes — statewide mandate (GMA jurisdictions, inside urban growth areas) | HB 1337 (2023) — RCW 36.70A.680–.681; SB 5184 (2025) — RCW 35A.21.445 | Cities and counties planning under the GMA must allow two ADUs per lot inside urban growth areas (attached + detached, or two of either), permit detached units, and may not require owner-occupancy, cap size below 1,000 sq ft, limit height below 24 ft, charge impact fees above 50% of the principal unit's, or require parking within ½ mile of a major transit stop (otherwise max 1 space on lots under 6,000 sq ft, 2 above) — RCW 36.70A.681; short-term-rental limits stay local (36.70A.680(5)). SB 5184: no minimum parking for homes under 1,200 sq ft in code cities over 30,000 (RCW 35A.21.445). |
| Maine | Yes — statewide mandate | LD 2003 (P.L. 2021, c. 672), 30-A M.R.S. § 4364-B, amended 2023 (c. 192) and 2025 (c. 385) | Every municipality must allow an ADU on the same lot as a single-family home or multi-unit building wherever residential uses are permitted (§ 4364-B(1)): at least one ADU per single-family lot (sub-§ 3(A)), exempt from density limits (sub-§ 4(A)), no parking beyond the house's own (sub-§ 4(C)) and, since the 2025 amendment, no owner-occupancy requirement (sub-§ 4(E)). Attached units take the house's setbacks; a town may set a maximum size, the state minimum is 190 sq ft (sub-§ 6). Exceptions: a Lewiston/Auburn water-supply watershed; shoreland zoning applies. |
| Vermont | Yes — statewide mandate | 24 V.S.A. § 4412(1)(E) (amended by Act 47 of 2023, eff. 1 July 2023) | No municipal bylaw may exclude, as a permitted use, one ADU located within or appurtenant to a single-family dwelling on an owner-occupied lot; a house with an ADU gets the same review, dimensional and other controls as a house without one, and converting an existing detached non-residential building may not be judged more strictly (§ 4412(1)(E)). Only flood-hazard and fluvial-erosion bylaws (§ 4424) are excepted; towns may still regulate short-term rentals separately (§ 4412(1)(F)). § 4412 itself sets no square-foot cap. |
| New Hampshire | Yes — statewide mandate (attached or detached since 1 July 2025) | RSA 674:72-73, amended by 2025, 197:2-3 (eff. 1 July 2025) | A zoning municipality must allow one ADU, attached or detached, as a matter of right in every district that permits single-family homes, with no lot-size, setback, frontage, design or aesthetic controls beyond a single-family house (674:72 I); if the ordinance is silent, one ADU is deemed permitted with only a building permit (II). Towns may require owner-occupancy of one unit (VI) and one added parking space (IV); living space is capped at 950 sq ft unless the town allows more, statutory floor 750 sq ft (VII); no familial or one-bedroom limits. |
| Massachusetts | Yes — statewide mandate | M.G.L. c. 40A § 3 (St. 2024, c. 150, § 8) / 760 CMR 71.00 | Since 2 February 2025 no c. 40A zoning by-law may prohibit, unreasonably restrict or require a special permit for one ADU, or its rental, in a single-family residential district: no owner-occupancy, at most 1 added parking space and none within 0.5 mile of a transit station (c. 40A § 3). Size: up to 900 sq ft or half the main house's gross floor area, whichever is smaller (c. 40A § 1A). 760 CMR 71.03 bars ADU-only impact fees and minimum lot sizes. Boston zones under its own 1956 enabling act, not c. 40A, so the mandate does not reach it. |
| Montana | Yes — all municipalities | MCA 76-2-345 (SB 528, 2023) | Every incorporated city or town with zoning must allow at least one ADU by right (no hearing, variance or conditional-use permit) on any lot with a single-family home; attached or detached units up to 75% of the home's floor area or 1,000 sq ft; no extra parking, owner-occupancy, relationship test, impact fees, design matching or street improvements; height, setback, lot-size and coverage rules no stricter than for the house; application fee capped at $250; non-compliant local rules void since Jan 1, 2024 (76-2-345(1)–(5)). County zoning is not covered. |
| Arizona | Yes — cities over 75,000 and all counties | A.R.S. §9-461.18 (HB 2720, 2024; HB 2928, 2025); §11-810.01 (counties) | Cities over 75,000 must allow one attached and one detached ADU as a permitted use on any lot where a single-family home is allowed, up to 75% of the home's floor area or 1,000 sq ft; no extra parking, owner-occupancy or relationship test, no design matching, rear/side setbacks capped at 5 ft (§9-461.18(A)–(B); default rule for non-adopters since Jan 1, 2025). Counties: same rules under §11-810.01 (default Jan 1, 2026). Pre-approved 200 / 600 / 1,000 sq ft ADU plans required from July 1, 2026 (§9-461.20(A)(4)). |
| District of Columbia | Yes — by right in R-1 to R-3 zones | Zoning Regulations of 2016, Subtitle U § 253; Z.C. Order 25-12 (eff. 10 July 2026) | One zoning code covers the whole District. An "accessory apartment" is a matter-of-right use in the R-1A, R-1B, R-2 and R-3 zones (U § 253.2): owner-occupancy of house or apartment (U § 253.5), at most 3 occupants (U § 253.6), an in-house unit capped at 35% of the house's gross floor area (U § 253.7), no parking required (C § 701.5). Since 10 July 2026 a detached accessory building may have a footprint of 650 sq ft in R-1/R-2, 550 sq ft in R-3, 2 storeys / 22 ft (D §§ 5002-5003, Z.C. 25-12). RF rowhouse zones use a "second principal unit" instead (U § 301). |
| Connecticut | Partial — opt-out (window closed 1 Jan 2023) | P.A. 21-29 § 6, C.G.S. § 8-2o (eff. 1 Jan 2022) | Zoning regulations must allow at least one accessory apartment as of right on every lot with a single-family house, attached or detached, with a size cap of no less than 30% of the house's net floor area or 1,000 sq ft, whichever is less; setbacks and lot size no stricter than for the house; at most one parking space; no familial, minimum-age or renewal conditions; decision within 65 days (§ 8-2o(a)-(b)). A town could opt out only by two-thirds votes of its zoning commission and legislative body; no opt-out is possible on or after 1 January 2023 (§ 8-2o(f)). |
| Rhode Island | Partial — by right in three cases | RIGL § 45-24-73 (P.L. 2024 ch. 284 / 285, eff. 25 June 2024), via § 45-24-37 | One ADU per lot must be allowed by right (1) on an owner-occupied lot as a reasonable accommodation for a family member with a disability, (2) on any residential lot of 20,000 sq ft or more, or (3) inside the existing footprint of the house or an accessory building (§ 45-24-73(a)); other ADUs follow local rules. Statewide: a local size cap must allow at least 900 sq ft or 60% of the house (1,200 sq ft for two bedrooms); at most one parking space per bedroom; no extra lot area or frontage; HOA bans void; no short-term rental (§ 45-24-73(b)). |
| Utah | Partial → detached mandate Oct 1, 2026 | HB 82 (2021), former Utah Code 10-9a-530; SB 284 (2026), Utah Code 10-21-304 | Internal ADUs have been a permitted use in primarily residential zones since 2021 (HB 82; former Utah Code 10-9a-530) — cities may still require owner residence, 1 parking space, a rental licence and 30-day minimum stays. From Oct 1, 2026, first- to fourth-class cities (and fifth-class cities of 5,000+ in first- to third-class counties) must permit a detached ADU on any lot of 11,000 sq ft or more with a single-family home, without a conditional-use permit, parking capped at 2 spaces (1 under 650 sq ft); owner residence and 90-day minimum rentals may still be required (10-21-304). |
| Colorado | Partial — MPO municipalities of 1,000+ | HB 24-1152 (C.R.S. 29-35-101 to -104, act numbering) | Since June 30, 2025 a 'subject jurisdiction' — a municipality of 1,000+ inside a metropolitan planning organization, or the part of a county inside a census-designated place of 40,000+ within an MPO — must allow one ADU by administrative approval wherever single-unit detached homes are allowed; it may not require a new off-street parking space (an existing one may be designated) or owner-occupancy beyond proof of residence at application, and must allow 500–750 sq ft units with setbacks no stricter than a house's (C.R.S. 29-35-102(18), 29-35-103). Elsewhere: local control. |
| Nevada | Partial — counties of 100,000+ and cities of 60,000+ | AB 396 (2025), Ch. 365, Stats. of Nevada 2025 | Counties of 100,000+ (Clark, Washoe) and cities of 60,000+ (Las Vegas, Henderson, North Las Vegas, Reno, Sparks) had to adopt ADU-authorizing ordinances by July 1, 2026, or ADUs become allowed on residential parcels without restriction until they do; ordinances may not require more than 1 parking space or prohibit kitchens. Adopted: Reno (Oct 2025), Clark County Ord. 5349 (Mar 5, 2026), Las Vegas Ord. 6963 (July 1, 2026); Henderson's standards already permit ADUs; North Las Vegas's code (through Aug 5, 2026) still requires a Special Use Permit. Elsewhere local zoning governs. |
| Hawaii | Partial — county ordinances due Dec 31, 2026 | Act 39, SLH 2024 (new HRS §46- section; SB 3202) | Each county must adopt ordinances allowing at least two ADUs, or the reasonable equivalent, on residentially zoned lots inside the state urban district, excluding special management areas and county-mapped hazard areas (§46-(b), (i)); a county that has not acted by Dec 31, 2026 may not deny a permit for up to two ADUs on a single-family lot on unit-count grounds (§46-(g)); no county may ban long-term rentals (§46-(h)). Until then county ordinances govern — Honolulu allows one ADU (plus an ohana unit) on R-3.5 to R-20 and Country lots; its two-ADU ordinance is pending. |
| Virginia | Partial — mandate from 1 July 2027; pre-2026 local ordinances exempt | SB 531 (2026) / Acts ch. 895, Va. Code § 15.2-2292.4 | Today each locality's zoning decides. SB 531 (approved 13 April 2026) adds § 15.2-2292.4, effective 1 July 2027: single-family zoning is deemed to include ADUs as a permitted accessory use; the locality issues an ADU permit for a fee of no more than $500; it may require a 30-day minimum lease and owner-occupancy only at application, may cap floor area at no less than 350 sq ft (lots under 2,500 sq ft) or 500 sq ft, and may not set setbacks, height or lot rules stricter than for the house. Localities with an ADU ordinance adopted before 2026 are exempt. |
| Texas | No statewide ADU law — local control | Local zoning; SB 673 (2025) died in the House | No Texas statute requires a city to allow ADUs; each city's zoning ordinance decides. SB 673 (89th Leg., 2025), a statewide ADU pre-emption bill (proposed Loc. Gov't Code Ch. 249: no owner-occupancy rule, no size cap below 800 sq ft, setbacks of 5 ft or less), passed the Senate but stopped at 05/26/2025 H Placed on General State Calendar — no House vote. The 2025 lot-size and mixed-use laws (SB 15, Loc. Gov't Code §211.052; SB 840, §218.002) apply only to cities over 150,000 in counties over 300,000 and contain no ADU provision. Next session: Jan. 12, 2027. |
| Florida | No statewide mandate — local control | Fla. Stat. §163.31771 (permissive); SB 48 died 2026 | Fla. Stat. §163.31771(3) says a local government may adopt an ordinance allowing ADUs in single-family zones — it requires nothing (last amended ch. 2020-27). SB 48 (2026), which would have required every county and city to allow ADUs by right by Dec. 1, 2026 and barred owner-occupancy rules, passed the Senate 38-0 on Feb. 4, 2026 and died in House messages on Mar. 13, 2026; House companion HB 313 died in subcommittee the same day. HB 1389 (ch. 2026-179), the housing bill that did pass, has no ADU provision. |
| New York | Local control (no statewide law) | Municipal home rule; NYC Zoning Resolution (City of Yes, 5 Dec 2024) | No state ADU statute: the 2021-22 bill (S4547-A / A4854-A) died in the Assembly Local Governments Committee (last action 5 January 2022). Towns, villages and cities regulate ADUs under their own zoning. NYC's City of Yes for Housing Opportunity (adopted 5 December 2024) allows one ADU of up to 800 sq ft on 1- and 2-family lots citywide by right, but bars backyard units in some low-density, historic and flood areas and basement units in flood areas. NYS HCR's Plus One ADU programme funds ADUs through participating localities. |
| Illinois | Local control | 65 ILCS 5/11-13 (local zoning); BUILD Plan (SB 4071 / HB 5626) not passed | No statute requires ADUs; municipalities zone under 65 ILCS 5/11-13 and counties under 55 ILCS 5/5-12. The BUILD Plan (SB 4071 / HB 5626, 104th G.A.), which would have required every municipality to allow ADUs by right from Jan. 1, 2027, did not pass in the spring 2026 session; the fall 2026 veto session is its next chance. Until then a city's own ADU ordinance is the whole rule. |
| Georgia | Local control | Local zoning; HB 1166 (2026) died in the Senate | No Georgia statute requires ADUs; the Zoning Procedures Law (O.C.G.A. Title 36, Ch. 66) leaves the decision to each city and county. HB 1166 (2025–2026 session) would have barred zoning decisions from blocking one dwelling of 400 sq ft or less on a residential lot; it passed the House 111–50 on Mar. 6, 2026 and was reported by the Senate State and Local Governmental Operations Committee by substitute on Mar. 27, 2026, but got no Senate floor vote before the session ended. |
| North Carolina | Local control | G.S. Ch. 160D; HB 765 / SB 205 (2025) stalled | No statute requires ADUs; cities and counties regulate them under G.S. Chapter 160D. HB 765 (2025, 'Save the American Dream Act') would have added G.S. 160D-975 requiring cities of 125,000 or more to allow one ADU per detached single-family home over 600 sq ft; its last action was re-referral to House Finance on 5/6/2025. The House folded the same provisions into SB 205 ('Swimming Pools/Housing Regulatory Reform'), last action re-referred to House Rules on 6/11/2025. Neither had moved as of mid-2026, and neither is law. |
| Minnesota | Local control | Minn. Stat. §462.357 (local zoning); Starter Home Act (2026) stalled | No statute requires ADUs; cities zone under Minn. Stat. §462.357. The 2026 Minnesota Starter Home Act (HF 3895, introduced Mar. 2, 2026; SF 4123, Mar. 4, 2026) stalled in committee and the regular session ended in May 2026 without passage. Minn. Stat. §462.3593 is a separate opt-out program for temporary family health care dwellings, not an ADU rule. |
| Pennsylvania | Local control (no statewide law) | Municipalities Planning Code (Act 247 of 1968), 53 P.S. § 10101 et seq. | Pennsylvania has no statewide ADU statute. Zoning is adopted municipality by municipality under the Municipalities Planning Code, so whether an ADU is a permitted use, its size cap and any owner-occupancy or family-only condition come entirely from the local zoning ordinance; many municipalities have no ADU use at all. Look for "accessory dwelling unit" in the municipal use table and check for a pending zoning amendment before planning. |
| New Mexico | Local control — no state ADU law | None (HB 425 of 2023, HB 554 of 2025 and HB 17 of 2026 all died) | New Mexico has no statewide ADU statute: HB 425 (2023) and HB 17 (2026, 'Accessory Dwelling Units in Certain Areas') were postponed indefinitely in House committee, and HB 554 (2025) died in Senate committee at adjournment. City and county zoning governs — Albuquerque's Integrated Development Ordinance allows one ADU as an accessory use in the R-A, R-1, R-T and R-ML zones with a 750 sq ft cap, one parking space and no owner-occupancy requirement; confirm the rules with your local planning department. |
| South Carolina | Local control | S.C. Code Title 6, Ch. 29 (local zoning) | No statute requires ADUs; cities and counties zone under the Local Government Comprehensive Planning Enabling Act (S.C. Code §6-29-310 et seq.). H. 3469 (2025–2026), the 'Accessory Dwelling Unit Affordable Housing Incentive Act', was a property-tax exemption (amending §12-37-220) for ADUs rented to tenants at or below 80% of area median income — not a zoning mandate — and never left House Ways and Means after its Jan. 14, 2025 introduction. |
| Tennessee | Local control | Tenn. Code Ann. Title 13, Ch. 7; HB 2031 / SB 2131 (2026) failed | No statute requires ADUs; municipal and county zoning powers come from Tenn. Code Ann. Title 13, Ch. 7. HB 2031 / SB 2131 (114th G.A., 2026) would have barred local governments from capping ADUs below 850 sq ft, requiring owner-occupancy, banning rentals, or requiring side/rear setbacks over 5 ft. HB 2031 was taken off notice in the House Cities & Counties Subcommittee on Mar. 11, 2026 and SB 2131 was sent to the Senate State & Local Government general subcommittee on Mar. 10, 2026 — neither passed. |
| Alabama | Local control | Code of Ala. Title 11, Ch. 52 (local zoning) | No Alabama statute requires or regulates ADUs; municipalities zone under Code of Ala. Title 11, Ch. 52, and each city's ordinance decides — several large Alabama cities still do not allow a second dwelling on a single-family lot, while others permit one only through a discretionary approval. No ADU bill has passed the Legislature, and none appears among the 2025 or 2026 regular-session instruments. |
| Michigan | Local control | Michigan Zoning Enabling Act (MCL 125.3101 et seq.); HB 5585 (2026) in committee | No statute requires ADUs; the Michigan Zoning Enabling Act (2006 PA 110, MCL 125.3101 et seq.) leaves them to each city, township and village — one large city allows them by right on every residential lot while another still prohibits them. HB 5585 (2026), which would amend §102 of the Act (MCL 125.3102) on 'zoning restrictions related to accessory dwelling units and mobile homes', was introduced Feb. 24, 2026 and referred to the House Government Operations Committee, where it remained as of June 2026. |
| Missouri | Local control | RSMo Ch. 89 (local zoning) | No statute requires ADUs; cities zone under RSMo Ch. 89 (§89.020) and counties under Ch. 64. No ADU statute has been enacted and the 2025 and 2026 regular-session Senate bill lists carry no accessory-dwelling bill, so a city's ordinance — including any owner-occupancy or size rule it adopts — is the whole rule. |
| New Jersey | Local control (no statewide law) | Municipal Land Use Law, N.J.S.A. 40:55D-1 et seq.; S1786 / A3488 pending | New Jersey has no statewide ADU statute; each municipality decides in its own zoning ordinance, adopted under the Municipal Land Use Law. A statewide bill, S1786 (Singleton) / A3488 (Lopez), "Concerns development of accessory dwelling units and related municipal land use regulations", was introduced in January 2026 for the 2026-27 session and had not been enacted as of 20 September 2026; the 2024-25 version (S2347) expired with that session. Until a state law passes, whether an ADU is allowed, how big it may be and whether the owner must live on site are set town by town. |
"Statewide mandate" means the state requires local governments to allow ADUs; "local control" means each city or county sets its own rules. Laws change frequently — verify with your local planning department. For the full state-by-state breakdown with law summaries, see Which States Allow ADUs?
The cities homeowners ask about most. Each page opens with a direct answer, the size and setback limits, permit fees and official application links.
We track detailed ADU rules for 26 states. Click a state for city comparisons.
3 cities covered. Average ADU-friendliness score: 3.0/10.
View Alabama ADU laws →14 cities covered. Average ADU-friendliness score: 6.4/10.
View Arizona ADU laws →38 cities covered. Average ADU-friendliness score: 7.3/10.
View California ADU laws →3 cities covered. Average ADU-friendliness score: 7.7/10.
View Colorado ADU laws →1 cities covered. Average ADU-friendliness score: 7.0/10.
View District of Columbia ADU laws →4 cities covered. Average ADU-friendliness score: 5.2/10.
View Florida ADU laws →2 cities covered. Average ADU-friendliness score: 6.0/10.
View Georgia ADU laws →1 cities covered. Average ADU-friendliness score: 7.0/10.
View Hawaii ADU laws →2 cities covered. Average ADU-friendliness score: 7.0/10.
View Illinois ADU laws →8 cities covered. Average ADU-friendliness score: 7.0/10.
View Massachusetts ADU laws →3 cities covered. Average ADU-friendliness score: 5.7/10.
View Michigan ADU laws →2 cities covered. Average ADU-friendliness score: 9.0/10.
View Minnesota ADU laws →1 cities covered. Average ADU-friendliness score: 7.0/10.
View Missouri ADU laws →3 cities covered. Average ADU-friendliness score: 6.0/10.
View Nevada ADU laws →4 cities covered. Average ADU-friendliness score: 6.8/10.
View New Jersey ADU laws →1 cities covered. Average ADU-friendliness score: 7.0/10.
View New Mexico ADU laws →3 cities covered. Average ADU-friendliness score: 4.3/10.
View New York ADU laws →3 cities covered. Average ADU-friendliness score: 8.0/10.
View North Carolina ADU laws →5 cities covered. Average ADU-friendliness score: 8.2/10.
View Oregon ADU laws →1 cities covered. Average ADU-friendliness score: 3.0/10.
View Pennsylvania ADU laws →1 cities covered. Average ADU-friendliness score: 6.0/10.
View South Carolina ADU laws →1 cities covered. Average ADU-friendliness score: 6.0/10.
View Tennessee ADU laws →8 cities covered. Average ADU-friendliness score: 5.2/10.
View Texas ADU laws →1 cities covered. Average ADU-friendliness score: 8.0/10.
View Utah ADU laws →2 cities covered. Average ADU-friendliness score: 6.5/10.
View Virginia ADU laws →10 cities covered. Average ADU-friendliness score: 8.4/10.
View Washington ADU laws →We're expanding coverage to all 50 states. Request a state to help us prioritize.
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