Where

ADU laws by state and location

ADU law is a state floor with local rules on top. This page is honest about which jurisdictions we have actually recorded, which today is none: a city page ships only once that jurisdiction’s own code supplies every field we require, down to the fee schedule and the last-reviewed date.

Coverage today

jurisdiction records published

A city page ships here only once that jurisdiction’s own code supplies every field we require. Until then this page says so.

The alternative, generating a page per city from the California state minimums with the city name substituted, would produce hundreds of URLs that look local and are not. That is the single most common pattern in ADU search results, and it is the reason this site exists.

California statewide rules are covered in ADU regulations; city-level evidence is in the research below.

What a city page must carry

Maximum size
Setbacks
Height
Parking
Owner-occupancy
Permit path
Fee schedule
Effective date
Official source
Last-reviewed date

State law

ADU laws by state

9 state pages, each built from the statute as published on the state’s own legislature or housing-agency site, checked 2026-10-27. A state appears here only once we have read its law there.

CaliforniaGov. Code §§ 66314–66342 (via the HCD ADU Handbook, January 2025). Detailed state code; 60-day decision clock; no owner-occupancy for ADUs; impact-fee exemption under 750 sq ft.Read the California rules →WashingtonRCW 36.70A.680–.681. Two ADUs per lot in urban growth areas; no owner-occupancy; 1,000 sq ft floor on size caps; impact fees capped at half.Read the Washington rules →MontanaMCA 76-2-345. One ADU by right; no parking, owner-occupancy or impact fees; size cap 75% of house or 1,000 sq ft.Read the Montana rules →ArizonaA.R.S. § 9-461.18. Cities over 75,000: one attached + one detached ADU; 5-ft side/rear setback cap; no parking or sprinkler mandate.Read the Arizona rules →ColoradoHB24-1152 (Session Laws 2024, Ch. 167). Covered metro jurisdictions: one ADU per detached home, administrative approval, from June 30, 2025.Read the Colorado rules →Maine30-A M.R.S. § 4364-B. One ADU per lot with 1–3 unit home; no extra parking; no owner-occupancy (2025); 190 sq ft minimum.Read the Maine rules →MassachusettsM.G.L. c. 40A §§ 1A, 3 (Acts of 2024, c. 150, §§ 7–8). One ADU by right in single-family zones; max 900 sq ft or half the house; no owner-occupancy; parking capped.Read the Massachusetts rules →MarylandLand Use Art. §§ 4-501–4-507 (2025 Md. Laws Ch. 196). Local ADU laws required by Oct 1, 2026; no impact fees under 750 sq ft; parking limits near transit.Read the Maryland rules →FloridaFla. Stat. § 163.31771. Local option: cities may allow ADUs; ADUs under the section need an affordable-rent affidavit.Read the Florida rules →

Not yet published: Oregon (Statute (ORS 197A.425) known, but the official ORS site refused connections on the retrieval date.) Utah (Official code site unreachable on the retrieval date.) Vermont (Official statutes site unreachable on the retrieval date.) New Hampshire (Official RSA site blocked our request on the retrieval date.) Connecticut (Official statutes site unreachable on the retrieval date.) Rhode Island (Official statutes site unreachable on the retrieval date.) Hawaii (Official HRS site blocked or timed out on the retrieval date.) Texas (No statewide ADU statute: SB 673 (2025) did not pass the House.) New York (No statewide ADU mandate found.) North Carolina (No statewide ADU mandate found.) Virginia (No statewide ADU mandate; § 15.2-2292.1 covers temporary family health care structures only.)

Permit data

Where we hold ADU permit data

Five California jurisdictions publish permit records detailed enough to show who builds ADUs there and how long approval takes.

Los Angeles1,995 contractors named on 3,782 ADU sites. Median 162 days from submission to an issued permit.Read the research →San Francisco783 contractors named on 1,296 ADU sites. Median 445 days from filing to an issued permit.Read the research →Sacramento353 contractors named on 736 ADU sites. The ten most active firms appear on 28% of them.Read the research →San José316 contractors named on 461 ADU sites. 81% of them appear on a single site only.Read the research →Marin (unincorporated)221 contractors named on 276 ADU sites. Median 174.5 days from receipt to an issued permit.Read the research → Your city is not here?Your planning department is the authority for your parcel. If you hold a sourced record for your jurisdiction, send it to us.Contact us →

Counts are named-contractor records from permit extracts harvested 29–30 August 2026; a firm named in two cities is counted in both.

City-level research

What we do have, at city level

Several research pages already carry genuinely local, sourced detail. Look there while the structured records are built.

Every California city’s ADU rules: the trackerThe widest local coverage we hold.ADU fees by city: the 750 square foot cliffCity fee schedules, sourced.How long an ADU takes to approve, by cityMeasured from permit records.Which California cities publish pre-approved ADU plansPlan catalogs, city by city.Where California cities publish permit dataThe primary sources themselves.

Outside California

The rest of the country

Our corpus is heavily Californian and we do not pretend otherwise. Start with the two studies here, then go to your own jurisdiction’s planning department, which is the only authority that can answer for your parcel in any state.

If you have a sourced jurisdiction record you think we should publish, or you spot an error in one of the research pages, send it to us.

Which states have actually legalized ADUsThe state-law picture. ADU growth outside CaliforniaDo the new laws work?

The one thing to take from this page

A state rule is a floor, not your answer.

Even where California guarantees you an 800 square foot unit with four-foot setbacks, your city may permit considerably more. On everything the state has not occupied, it may require considerably more of you. Check the local record before you design anything.

Questions

Questions people ask

Do ADU rules vary by city?

Substantially. In California a state floor applies everywhere, but size limits above that floor, design standards, fees, and the permit path itself are set locally. A rule quoted without its jurisdiction cannot be relied on.

Why do you not have a page for my city?

Because we have not yet recorded that jurisdiction’s own code against our own standard. We would rather say that than publish a page that is the state default with your city’s name on it, which is what most city ADU pages online actually are.