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S.B. 284 (2026) enacted Utah Code § 10-21-304, which takes effect on October 1, 2026. It requires every specified municipality to adopt a land use regulation that permits a detached accessory dwelling unit on any lot or parcel of 11,000 square feet or larger that contains a single-family dwelling, where the single-family dwelling is a permitted use.
A "specified municipality" is a city of the first, second, third or fourth class, or a city of the fifth class with a population of 5,000 or more located in a county of the first, second or third class (§ 10-21-101). Unincorporated areas are not municipalities.
A city must require detached ADUs to meet building, health and fire codes, and must provide a way to convert a legally built accessory structure into a detached ADU. It may not require a conditional use permit in a primarily residential zone, more than one on-site parking space for a detached ADU under 650 sq ft, or more than two for one of 650 sq ft or more. It may allow detached ADUs on lots smaller than 11,000 sq ft.
Size, dimension, height and lot coverage; setbacks; design consistent with the home; owner occupancy of the home or the ADU; one ADU per lot; and it may prohibit a detached ADU that is larger than the home, in a front yard or a recorded easement, rented for less than 90 consecutive days, or without adequate utility access or capacity.
Summarized from the enrolled bill: S.B. 284, Local Land and Water Modifications (2026). Not legal advice. See each city's rules.