Can I Build an ADU (Accessory Dwelling Unit) in Utah?
Quick Answer
Yes — Utah state law requires most cities to allow internal ADUs.
Utah State Law (HB 82)
Since 2021, Utah HB 82 requires cities to allow at least internal ADUs (within the existing footprint of the home — basement apartments, above-garage units, etc.). Many cities also allow detached ADUs, though rules on size and placement vary. This means most Utah homeowners can legally build an ADU.
Types of ADUs
Internal ADUs include basement apartments, converted attic space, and attached additions. Detached ADUs include backyard cottages, converted garages, and purpose-built accessory structures. Each type has different permit requirements and setback rules.
Key Requirements
All ADUs in Utah need: separate entrance from the primary dwelling, adequate parking (usually one additional off-street space), fire separation (1-hour rating for internal ADUs), and compliance with all building codes for habitable space. Basement ADUs require egress windows in every bedroom.
Reduced Impact Fees
Utah law limits impact fees for ADUs, making them cheaper to permit than a full second dwelling. Many cities waive or significantly reduce impact fees for ADUs. Ask your city about current fee schedules — this can save thousands of dollars.
Bottom Line
Yes, you can build an ADU in most Utah cities thanks to state law. Internal ADUs are the easiest path. Start by checking your city's specific ADU ordinance.