ADU Laws by State (2026): Where You Can Build, By Right
21 states now have a statewide ADU law. The rest leave it to cities. Find your state to see what you can build, what your city still controls, and what's changing. Last verified September, 2026.
- 10ADU-friendly states
- 11W.i.P. states
- 29 + DCT.B.D.
How we rate states
ADU-Friendly, W.i.P., or T.B.D.?
Every state gets one of three labels, based on what its statewide ADU law requires cities to allow.
ADU-friendly
A statewide law requires cities to allow ADUs and limits the rules they can use to block them, such as parking, owner-occupancy, and size caps.
W.i.P.
Work in progress. A statewide ADU law exists, but it leaves big gaps — it applies only in some areas, or lets cities keep key restrictions.
T.B.D.
To be determined. No meaningful statewide ADU law yet, so the rules are set city by city.
The basics
State Law Sets the Floor. Your City Sets the Rest.
A statewide ADU law tells cities what they must allow — for example, that an ADU can't be denied just because the lot lacks an extra parking space. Cities can be more generous than the state, but in an ADU-friendly state they can't be stricter.
Some rules almost always stay local: overlay districts, exact setbacks, utility and septic capacity, short-term rental limits, and permitting timelines. That's why every state page ends with a checklist for your city.
ADU-friendly
10 ADU-Friendly States
Statewide laws that make ADUs allowed by right on most single-family lots. Pick your state for size limits, parking, owner-occupancy, and approval rules.
W.i.P.
11 States With ADU Laws in Progress
A statewide ADU law is on the books, but cities still control a lot. Pick your state to see what the law covers and what it leaves out.
T.B.D.: 29 States and DC Without a Statewide ADU Law
These states leave ADU rules to cities and counties. You may still be able to build — check your local zoning code, and use the city checklist on any of our state pages as a guide. We'll add a page for each state as its law develops.
- AL · Alabama
- AK · Alaska
- DE · Delaware
- DC · District of Columbia
- GA · Georgia
- IL · Illinois
- IN · Indiana
- KS · Kansas
- KY · Kentucky
- LA · Louisiana
- MI · Michigan
- MN · Minnesota
- MS · Mississippi
- MO · Missouri
- NE · Nebraska
- NJ · New Jersey
- NY · New York
- NC · North Carolina
- ND · North Dakota
- OH · Ohio
- OK · Oklahoma
- PA · Pennsylvania
- SC · South Carolina
- SD · South Dakota
- TN · Tennessee
- TX · Texas
- VA · Virginia
- WV · West Virginia
- WI · Wisconsin
- WY · Wyoming
What to compare
The 5 Rules That Decide What You Can Build
Every state page answers these five questions first.
Do you have to live on the property — in the main house or the ADU — to build or rent one? Many ADU-friendly states have banned this requirement.
Does the ADU need its own off-street parking space? Many states waive it near transit or for garage conversions.
Is the ADU approved by right by city staff, or does it go through a public hearing where neighbors can object?
Are the fees cities charge for new units waived or capped for small ADUs, or set locally?
Can an HOA or deed restriction block an ADU that state law allows? Only some states limit HOA rules.
See what fits your lot before you spend on design
Browse pre-designed ADU plans and place one in your own backyard.
HomeWiP
How HomeWiP Helps, Wherever You Build
Plans curated by a team that knows what plan checkers look for, so your ADU is ready to for engineering wherever you are ready to get started.
- View pre-designed plans in your backyard
Pre-designed ADU plans
Pre-designed ADU plans you can place in your own backyard, compare side by side, and take to your city for an initial consultation.
Where our expertise comes from
7+ years laser-focused on ADUs, 700+ plans in the directory, and projects across 20+ cities and counties. We know what gets stuck in plan check, and we design to avoid it.
FAQ
ADU Laws by State: Frequently Asked Questions
By our rating, 10 states are ADU-friendly: Arizona, Arkansas, California, Colorado, Iowa, Maine, Massachusetts, Montana, Oregon, and Washington. Their statewide laws require cities to allow ADUs and limit how cities can restrict them.
Not by state law. 21 states have a statewide ADU law of some kind. In the other 29 states and DC, ADU rules are set city by city — many cities allow them, some don't.
Work in progress. The state has an ADU law, but it leaves big gaps — for example, it applies only in some areas, or lets cities keep rules like owner-occupancy or parking requirements.
Often, yes. Without a statewide law, your city or county decides. Look up your zoning district, read the local zoning ordinance, and ask for a pre-application meeting. Note that not every State knows secondary backyard homes as accessory dwelling units (ADUs). They may be called a guesthouse, or another name that carries the same meaning.
It depends on the state. A few states limit HOA and deed restrictions on ADUs; most don't. Check your state's page for its HOA rule.
We review every state twice a year and whenever a new ADU law passes. Each state page shows the date it was last verified.
Plan Your ADU With Ready-to-Permit Designs
Ready to permit
Whatever your state's rules, start with a plan designed to get through plan check.
How we rate states
Ratings are based on each state's ADU statute and the Mercatus Center's Taxonomy of State ADU Laws, cross-checked against state housing agency guidance. We don't rate individual cities or counties.
Last verified: October 10, 2026.