ADU rules in Bountiful

A detached ADU is a conditional use reviewed and approved by the Bountiful City Administrative Committee, and only in the Single-Family Residential (R), Residential Multiple (RM) Family, and Downtown (DN) Mixed Use zones. The lot must already contain a habitable single-family dwelling, must have at least 8,000 square feet of buildable land, and the property must be owner occupied; a detached ADU is unlawful on a duplex or multi-family building or property. It must sit behind the front building line and meet accessory-structure setbacks, which since Ord. 2025-13 allow either 20 feet of height with 3 foot rear and interior side setbacks (if at least 10 feet behind the front building line) or up to 25 feet with 8 foot setbacks. Utah Code 10-21-304, effective October 1, 2026, will bar the city from requiring a conditional use permit for a detached ADU in a primarily residential zone, and draft Ordinance 2026-10 would make these units staff-approved permitted uses; it had not been adopted when this entry was verified.

An internal ADU (one created within the primary dwelling and within its footprint at the time of creation) is a permitted use reviewed and approved by City Staff, in the Single-Family Residential, RM, and DN Mixed Use zones only. The property must be owner occupied, only one ADU is allowed per lot, and the structure must keep the outward appearance of a single-family home. A basement ADU may share a common entrance with the main unit if each unit has its own interior door; otherwise the separate entrance must be on the side or rear, with a walkway, and must not make the house look like a duplex.

A detached ADU must be at least 350 square feet and may not exceed 1,250 square feet, and may not be built on a lot with less than 8,000 square feet of buildable land. Height comes from the accessory-structure standards: 20 feet to the peak and 15 feet to the eave under the standard option, or up to 25 feet with a 20 foot eave under the ADU-only enhanced option that requires 8 foot rear and side setbacks. The internal ADU criteria set no square-foot limit, but an internal ADU must fit within the footprint of the primary dwelling as it stood when the unit was created.

For both detached and internal ADUs the property owner must occupy either the principal unit or the ADU as a permanent residence and may at no time receive rent for the owner-occupied unit. The application must include proof of owner occupancy (voter registration, vehicle registration, driver's license, county assessor records, or similar). A deed restriction limiting the property to single-family use, prepared by the Planning Director and signed by all owners, must be recorded with the Davis County Recorder before the ADU is occupied, or before the building permit is issued if one is required. Utah law expressly leaves this requirement to cities for internal units, and will continue to allow it for detached units after the October 1, 2026 state mandate takes effect.

Adequate off-street parking is required for both the primary residence and the ADU, and one off-street space must be provided for the ADU on top of the parking required for the principal unit at the time of construction. The rule is identical for detached and internal units. Any additional occupant vehicles must be parked off-street in code-compliant areas; on-street parking may be used only within the limits of the Bountiful Traffic Code. A detached ADU designed for vehicle parking must be connected to the street by a paved driveway.

Internal ADUs are a permitted use reviewed and approved by City Staff, while detached ADUs need a conditional use permit from the Bountiful City Administrative Committee; the Approval and Review Bodies table in 14-2-111 assigns detached ADU conditional use permits to the Administrative Committee as the final body and internal ADUs to Staff. It is unlawful to live in, or let anyone live in, an ADU that has not received that permit or written authorization from the Planning Department. Applications for both types, and for a short-term rental permit, are filed through the city's CityInspect portal. Under draft Ordinance 2026-10 the detached unit would move to staff review as a permitted use.

An internal ADU is defined as a unit created for a long-term rental of 30 consecutive days or longer, and the internal ADU criteria still carry a sentence saying that effective April 1, 2022 short term rentals of 30 days or less are prohibited. Chapter 14 separately allows short-term rentals, but only inside an approved accessory dwelling unit and only in the R, RM and DN zones: renting an entire single-family home, duplex or multi-family property short term is unlawful. A short-term rental needs its own permit, reviewed in a public meeting by the Administrative Committee after mailed notice to owners within 300 feet and a posted sign, costing $225 (or $100 if the applicant already has an ADU or applies for one at the same time). The permit does not run with the land, requires a city business license, and the owner may at no time receive rent for the unit they occupy themselves.