ADU Laws by State —
What the Law Says
Where You Live.

How ADU Zoning Works in the U.S.

ADU law in the United States operates at three levels: state law, local zoning ordinance, and HOA governing documents. State law sets the floor — the minimum that must be allowed. Local zoning adds specific rules within that floor. HOA CC&Rs can add additional restrictions where state law doesn't preempt them.

The critical question for any homeowner is: Does your state have a statewide ADU mandate? If yes, your city cannot prohibit ADUs or impose conditions that effectively make them infeasible. If no, your city has almost complete authority over whether ADUs are allowed at all — and what conditions they carry.

The three levels of ADU law

State law — Sets minimum standards that cities must meet or exceed. States with statewide mandates (California, Washington, Oregon, Virginia, Colorado, Massachusetts, Minnesota, and others) require municipalities to allow ADUs by right with minimal conditions. States without mandates allow cities to set their own rules.

Local zoning ordinance — Implements state requirements and adds local standards: setbacks, size limits, design requirements, parking rules, and owner-occupancy conditions. Even in states with strong statewide laws, local ordinances vary significantly. Always verify your specific city's current ADU ordinance — many are still updating to comply with newer state laws.

HOA governing documents — In most states, HOA CC&Rs can restrict ADUs even where zoning allows them. California is the primary exception — state law prohibits HOAs from banning ADUs. Always review your HOA's governing documents before investing in ADU design.

States With Statewide ADU Laws — 2026

These states have enacted legislation that requires municipalities to allow ADUs by right — meaning administrative approval without discretionary review — and prohibits local governments from imposing conditions that effectively make ADUs infeasible.

* "ADUs by Right" means administrative approval — no discretionary hearing, no neighbor notice, no planning commission vote. "No Owner-Occ." means the state prohibits owner-occupancy requirements for at least some ADU types. Max size shows state minimums — cities can be more permissive. Always verify current local standards.

Detailed Law Profiles — The Most Important States

ADU Rules — Major States Without Statewide Mandates

In states without statewide ADU mandates, rules are set entirely at the municipal level. The following reflects common patterns in major cities — always verify your specific city's current ordinance before beginning design.

* This table reflects city-level patterns as of June 2026. Many cities are actively updating their ADU ordinances. Always verify current local rules with your planning department before beginning design. For detailed city-by-city breakdowns, see the relevant state guide.

Key ADU Rules — What They Mean for Your Project

ADU Permissiveness Tiers

Based on statewide law strength, owner-occupancy rules, size limits, permit timelines, and fee restrictions, here is how states rank for ADU permissiveness in 2026.

HOA Restrictions on ADUs

HOA CC&Rs (Covenants, Conditions, and Restrictions) are private contracts that run with the land. In most states they can restrict ADUs even where zoning permits them. This is one of the most commonly overlooked issues in ADU planning — and one of the most expensive to discover after investing in design.

California — HOAs cannot prohibit ADUs

California Civil Code Section 4751 prohibits HOAs from enforcing any provision that effectively prohibits or unreasonably restricts the construction of ADUs or JADUs. This is a powerful protection — California homeowners in HOA communities have the same ADU rights as those without HOAs. HOAs can still regulate aesthetics to a reasonable degree.

All other states — check your CC&Rs first

In virtually every other state, HOA CC&Rs can legally prohibit ADUs, prohibit rentals, restrict additions, or require HOA board approval for construction projects. Before investing a single dollar in ADU design in an HOA community, read your CC&Rs specifically for language on: additional dwelling units, rental restrictions, construction approval requirements, and architectural standards.

Amending HOA CC&Rs

If your HOA CC&Rs prohibit ADUs and you're in a state where HOAs retain that authority, amending the CC&Rs is theoretically possible — but typically requires a supermajority vote of all homeowners (often 67–75%) and can take years. It is rarely a practical near-term path for a single homeowner wanting to build an ADU.

Frequently Asked Questions