ADU Regulations by State: All 50 States + DC Ranked
ADU (Accessory Dwelling Unit) regulations vary enormously across the United States. 21 states have enacted statewide ADU laws that preempt local restrictions, while the remaining 30 leave ADU rules entirely to local jurisdictions. This ranking shows every state's ADU-friendliness score, key regulations, and ease of building. Click any state for full details, city-level data, and building guidance.
All States Ranked by ADU-Friendliness
States are ranked by our ADU-friendliness score (0-100), which factors in whether the state has a statewide ADU law, owner-occupancy requirements, parking mandates, size limits, permitting timelines, and impact fees. Green indicates ADU-friendly states; red indicates restrictive states.
| # | State | Score | Statewide Law | Max Size | Parking Req? | Owner Occ? | Ease |
|---|---|---|---|---|---|---|---|
| 1 | Washington (WA) | 96 | Yes | 1,000 sq ft | No | No | Easy |
| 2 | Vermont (VT) | 95 | Yes | 900 sq ft | No | No | Easy |
| 3 | Arizona (AZ) | 93 | Yes | 1,000 sq ft | No | No | Easy |
| 4 | California (CA) | 93 | Yes | 1,200 sq ft | No | No | Easy |
| 5 | Oregon (OR) | 93 | Yes | 900 sq ft | No | No | Easy |
| 6 | Colorado (CO) | 91 | Yes | 1,000 sq ft | No | No | Easy |
| 7 | Minnesota (MN) | 88 | Yes | Set locally | No | No | Easy |
| 8 | Massachusetts (MA) | 85 | Yes | 900 sq ft | No | No | Easy |
| 9 | Connecticut (CT) | 83 | Yes | 1,000 sq ft | No | No | Easy |
| 10 | Maine (ME) | 80 | Yes | Set locally | No | No | Easy |
| 11 | Florida (FL) | 78 | Yes | Set locally | No | No | Easy |
| 12 | Montana (MT) | 78 | Yes | Set locally | No | No | Easy |
| 13 | Nevada (NV) | 78 | Yes | Set locally | No | No | Moderate |
| 14 | New York (NY) | 76 | Yes | 1,000 sq ft | No | Yes | Easy |
| 15 | Hawaii (HI) | 75 | Yes | 800 sq ft | No | No | Moderate |
| 16 | Virginia (VA) | 75 | Yes | Set locally | No | No | Moderate |
| 17 | District of Columbia (DC) | 70 | Yes | 900 sq ft | No | Yes | Moderate |
| 18 | New Jersey (NJ) | 66 | Yes | 1,000 sq ft | No | Yes | Moderate |
| 19 | Rhode Island (RI) | 63 | Yes | 900 sq ft | No | Yes | Moderate |
| 20 | New Hampshire (NH) | 55 | Yes | 800 sq ft | Yes | Yes | Moderate |
| 21 | New Mexico (NM) | 55 | No | Set locally | No | No | Moderate |
| 22 | Utah (UT) | 50 | Yes | Set locally | Yes | Yes | Moderate |
| 23 | Alaska (AK) | 45 | No | Set locally | Yes | No | Moderate |
| 24 | Alabama (AL) | 30 | No | Set locally | Yes | Yes | Difficult |
| 25 | Arkansas (AR) | 30 | No | Set locally | Yes | Yes | Difficult |
| 26 | Delaware (DE) | 30 | No | Set locally | Yes | Yes | Moderate |
| 27 | Georgia (GA) | 30 | No | Set locally | Yes | Yes | Moderate |
| 28 | Idaho (ID) | 30 | No | Set locally | Yes | Yes | Moderate |
| 29 | Illinois (IL) | 30 | No | Set locally | Yes | Yes | Moderate |
| 30 | Indiana (IN) | 30 | No | Set locally | Yes | Yes | Difficult |
| 31 | Iowa (IA) | 30 | No | Set locally | Yes | Yes | Difficult |
| 32 | Kansas (KS) | 30 | No | Set locally | Yes | Yes | Difficult |
| 33 | Kentucky (KY) | 30 | No | Set locally | Yes | Yes | Difficult |
| 34 | Louisiana (LA) | 30 | No | Set locally | Yes | Yes | Moderate |
| 35 | Maryland (MD) | 30 | No | Set locally | Yes | Yes | Moderate |
| 36 | Michigan (MI) | 30 | No | Set locally | Yes | Yes | Moderate |
| 37 | Mississippi (MS) | 30 | No | Set locally | Yes | Yes | Very Difficult |
| 38 | Missouri (MO) | 30 | No | Set locally | Yes | Yes | Moderate |
| 39 | Nebraska (NE) | 30 | No | Set locally | Yes | Yes | Moderate |
| 40 | North Carolina (NC) | 30 | No | Set locally | Yes | Yes | Moderate |
| 41 | North Dakota (ND) | 30 | No | Set locally | Yes | Yes | Moderate |
| 42 | Ohio (OH) | 30 | No | Set locally | Yes | Yes | Moderate |
| 43 | Oklahoma (OK) | 30 | No | Set locally | Yes | Yes | Moderate |
| 44 | Pennsylvania (PA) | 30 | No | Set locally | Yes | Yes | Moderate |
| 45 | South Carolina (SC) | 30 | No | Set locally | Yes | Yes | Difficult |
| 46 | South Dakota (SD) | 30 | No | Set locally | Yes | Yes | Moderate |
| 47 | Tennessee (TN) | 30 | No | Set locally | Yes | Yes | Moderate |
| 48 | Texas (TX) | 30 | No | Set locally | Yes | Yes | Moderate |
| 49 | West Virginia (WV) | 30 | No | Set locally | Yes | Yes | Difficult |
| 50 | Wisconsin (WI) | 30 | No | Set locally | Yes | Yes | Moderate |
| 51 | Wyoming (WY) | 30 | No | Set locally | Yes | Yes | Moderate |
Regional ADU Policy Patterns
West Coast: Leading the ADU Revolution
California, Oregon, and Washington have the most established ADU frameworks in the country. California pioneered statewide ADU reform starting in 2016 and has progressively strengthened its laws through bills like SB 9, AB 2221, and AB 1033 (which allows ADU condo conversion). Oregon requires cities to allow 2 ADUs per lot. Washington's HB 1337 (2023) is among the strongest ADU laws nationally. Portland and Seattle lead the nation in per-capita ADU construction.
Northeast: Rapid Recent Reform
The Northeast has seen a wave of ADU legislation since 2021. Connecticut, Vermont, Massachusetts, New York, New Jersey, and Rhode Island all passed statewide ADU mandates between 2021-2024. Maine's LD 2003 requires all municipalities to allow 2 ADUs per lot. New Hampshire was an early mover with its 2017 law, though it allows more local discretion than newer laws. These reforms are driven by severe housing shortages and high costs in the region.
South and Southeast: Emerging but Mixed
Florida's Live Local Act (2023) made it the first Southern state with a comprehensive statewide ADU mandate. Virginia followed with HB 2045 in 2024. Texas has no statewide law, but Austin's HOME initiative (2024) and Houston's lack of zoning make those cities ADU-friendly. Most other Southern states lack statewide ADU laws, though cities like Atlanta, Nashville, and Charlotte have adopted progressive local ordinances.
Midwest and Mountain West: Growing Momentum
Minnesota and Montana passed strong statewide ADU laws in 2023. Colorado followed with HB 24-1152 in 2024. Utah's SB 174 (2021) requires municipalities to allow at least one type of ADU. Kansas City, MO and Columbus, OH have adopted permissive local ADU ordinances. The Midwest shows the widest intra-regional variation, from very ADU-friendly (Minneapolis) to very restrictive (Mississippi).
About This Data
ADU regulations in our database are sourced from state legislation, municipal zoning codes, and planning department publications. Data is current as of early 2026. Our ADU-friendliness score weighs statewide law status, owner-occupancy requirements, parking mandates, size limits, permitting timelines, and impact fees. Scores are relative -- a score of 75+ indicates a very ADU-friendly state, while below 20 indicates significant barriers.
ADU regulations change frequently as new legislation is enacted. For the most current rules, check your state legislature and local planning department. Use our lookup tool to find the specific regulations for your state and city.