Utah Internal ADU Statewide Preemption Law

Utah Code Section 10-9a-530 mandates that every municipality permit at least one internal ADU as a use by right within an owner-occupied primary single-family dwelling located in a residential zone. Cities may impose reasonable standards including a single off-street parking space, owner-occupancy, prohibition of short-term rentals under 30 days, and registration requirements, but cannot outright ban internal ADUs. Detached ADUs remain subject to local zoning discretion. Counties have parallel authority under 17-27a-526. The law was passed in 2021 to expand housing supply across Utah while preserving neighborhood character through narrowly defined regulatory limits.

Municipal denial of compliant internal ADU permits may result in legal challenge and attorney fees. Property owners violating registration or occupancy conditions face local code enforcement.