What States Allow ADUs in 2026 (Full Map + Permit Fee Comparison)

If you own a home and you have been quietly running the numbers on adding a backyard cottage, a garage conversion, or a basement suite, the first question is never "how much will it cost." It is "am I even allowed to do this?"

The answer in 2026 is more permissive than it was three years ago, but it still depends almost entirely on which state you live in, and in many cases, which city inside that state. This is the map most homeowners cannot find in one place — pulled together because it is the single most common question we hear from people considering a modular accessory dwelling unit.

Why the 2026 Map Looks Different from the 2023 Map

Three things shifted between 2023 and 2026.

First, statewide preemption laws. Oregon kicked this off back in 2017 with House Bill 2001. California followed with the SB 9 and SB 10 stack. A wave of Northeast states — Vermont, Maine, New Hampshire, Massachusetts — passed their own versions in 2023-2024. Montana joined in 2023. The pattern is consistent: the state legislature gets tired of local jurisdictions blocking housing supply and passes a floor that cities cannot go below.

Second, federal financing got friendlier. HUD updated its guidance on FHA-insured loans for properties with ADUs, and the FHA Title I program (originally a 1930s home improvement loan) was modernized in 2024 to better cover ADU construction.

Third, modular construction matured. Factory-built units that ship to a prepared foundation collapsed the build timeline from 12-18 months down to 3-6 months in most jurisdictions. The legal door is open in more places, the money is available, and the unit itself can show up on a flatbed.

The State-by-State Comparison Table

Screenshot it, save it, share it. We have focused on the 15 states where homeowner interest is highest and where the legal picture is meaningful enough to summarize.

Permit fees are typical ranges based on published municipal fee schedules in each state's largest metros. They vary significantly by jurisdiction and do not include impact fees, school fees, or utility connection costs, which can add several thousand dollars in some markets. Treat them as orientation, not a quote.

Regional Breakdown

West Coast: The Leaders

California, Oregon, and Washington are in a category of their own. All three states removed owner-occupancy requirements at the state level, all three preempt local minimum lot sizes for ADUs, and all three require cities to process ADU permits within a fixed time window (typically 60 days in California). If you own a single-family lot on the West Coast, your default assumption should be that you can build an ADU. The exceptions are narrow: fire severity zones, coastal commission overlays, and a handful of historic districts.

California specifically allows both an ADU and a junior ADU (JADU, typically a converted bedroom with its own entrance) on the same lot, which means many homeowners are running two rental units off a single-family parcel. The Terner Center for Housing Innovation at UC Berkeley has tracked permit volumes year over year and California is producing more ADUs annually than the next ten states combined.

Northeast: The Catch-up Wave

Maine, Vermont, New Hampshire, and Massachusetts all passed statewide ADU laws between 2023 and 2024. The Northeast was historically the most restrictive region in the country for accessory housing, so this shift is significant. The laws are similar in shape to Oregon's: cities cannot ban ADUs on single-family lots, cannot require additional parking in most cases, and cannot impose owner-occupancy as a condition.

New York is the asterisk. New York City has its own ADU framework that is far more restrictive than the statewide laws in neighboring states, and the rest of the state operates under local zoning. If you own in upstate New York, your answer comes from your town, not Albany.

Mountain West: Mixed, Trending Open

Montana passed a statewide ADU law in 2023 that mirrors Oregon's approach. Colorado has not passed statewide preemption, but Denver, Boulder, and a growing list of Front Range cities have permissive local rules. Utah's HB 82 allows internal ADUs (basement units, converted garages attached to the main house) statewide but does not cover detached units, which still require local approval. Arizona is fully local, with Phoenix and Tucson running the most active permit programs.

Southeast: Local Game, Growing Fast

Georgia, North Carolina, Florida, and the rest of the Southeast operate entirely under local zoning. There is no statewide ADU mandate in any Southeast state as of 2026, and no serious legislative push to change that. What is happening instead is city-by-city reform. Atlanta updated its ADU ordinance in 2022 and is now one of the more permissive Southeast metros. Charlotte, Raleigh, and Asheville all allow ADUs with conditions. Florida is uneven: Miami-Dade is permissive, much of the Panhandle is not.

If you are in the Southeast, the practical move is to look up your specific city's accessory dwelling ordinance, not your state's housing code.

Midwest: The Quiet Region

The Midwest is the region we have the least to say about, which itself is the story. No statewide mandates, limited municipal reform outside of Minneapolis and a handful of college towns, and modest homeowner interest relative to coastal markets. If you own in Ohio, Indiana, Michigan, Wisconsin, or Illinois outside Chicago, expect local zoning to govern and expect the process to feel slower than what you would encounter on the West Coast.

The Federal ADU Push

Two federal programs matter for ADUs in 2026, and both are worth understanding even if your state already allows what you want to build.

FHA financing on properties with ADUs. HUD updated its appraisal and underwriting guidance in 2023 and 2024 to recognize rental income from ADUs when qualifying for an FHA-insured purchase or refinance loan. The practical effect: a buyer can now use projected ADU rental income to qualify for a larger mortgage on the primary home, which is a meaningful shift. Lenders implement this differently, so if you are considering buying a home with an existing ADU or adding one shortly after purchase, ask your loan officer specifically about FHA's current ADU income recognition rules.

FHA Title I loans for ADU construction. Title I is an old program originally designed for home improvement financing. HUD modernized it in 2024 with explicit language covering manufactured and modular ADU construction. The loan limits were raised and the program is now genuinely useful for homeowners building a detached unit on an existing lot.

HUD publishes a regularly updated set of ADU policy resources, model ordinances, and case studies. AARP also publishes one of the most comprehensive ADU policy reports in the country, updated annually, which is worth reading if you want to understand the legislative landscape in detail.

PERCH walks homeowners through financing options as an educational service. We are not a lender, we do not originate loans, and we do not pretend to. What we do is map the landscape so you know which questions to ask your bank, your credit union, or your FHA-approved lender.

Common ADU Zoning Restrictions Even in Permissive States

Even in California or Oregon, "allowed" does not mean "no rules." The most common restrictions you will encounter:

• Setbacks. Most jurisdictions require a minimum distance from property lines, typically 4-5 feet.
• Height limits. Detached ADUs are commonly capped at 16-25 feet depending on the city.
• Maximum unit size. Usually between 750 and 1,200 square feet.
• Parking requirements. Many statewide laws have eliminated parking requirements within a half-mile of transit, but parking can still be required in suburban and rural areas.
• Short-term rental bans. A growing number of cities allow ADUs but ban using them as short-term rentals (Airbnb, VRBO).
• Design review. Historic districts, design overlays, and HOAs can still impose aesthetic requirements.

The owner-occupancy question is the one that catches the most people off guard. In statewide-mandate states, the answer is no. In most other states, the city ordinance will require the property owner to live in either the primary home or the ADU itself. That single requirement is what separates a flexible investment property from a constrained one.

How to Verify the Rules for Your Lot

Three steps, in this order:

1. Look up your city's ADU ordinance. Search "[your city] accessory dwelling unit ordinance" and read the actual code, not a summary.
2. Confirm your lot's zoning designation. Most cities have an interactive zoning map. Your lot has a specific designation (R-1, R-2, RS-5, etc.) and the ADU rules attach to that designation.
3. Call the planning department. Planners answer the phone and they will tell you, in plain language, whether an ADU is allowed on your specific lot and what the process looks like. Budget 20 minutes for the call.

If any of those three steps surfaces a "no" or a "maybe," that is your answer. Do not spend money on plans or units until the legality is settled.