Davis County · about 26,000

Farmington

Detached allowed on larger lots

Farmington has a clear ADU toolkit: internal units on lots of 6,000 sf or more, detached units on lots of 10,000 sf or more. A rare subordinate-single-family path can place a qualifying unit on its own lot.

Internal ADU: Permitted on lots of 6,000 sf or larger.
Detached ADU: Permitted on lots of 10,000 sf or larger. The detached unit must be subordinate to the footprint of the primary dwelling.
Lot: IADU: 6,000 square feet. Detached: 10,000 square feet, which is below the state floor and therefore allowed. A lot of 11,000 square feet or larger is also covered by the statewide permitted-use rule now in effect.
Size: The detached unit must remain subordinate to the primary footprint, and it may not exceed the house. A city may keep that limit.
Parking: One additional off-street stall.
Owner occupancy: Required. Temporary absence may be allowed for military service, employment, or family obligations.
Rental: Prohibited as short-term rental. Occupancy of 30 days or more.
Design: One ADU per lot unless the subordinate-single-family path is approved separately.

Notes

The subordinate-single-family (SSF) path can create a separately owned dwelling. It needs Planning Commission approval, separate utilities, and two years of owner occupancy after separation. That is a different project from a backyard ADU.

Source: Farmington ADU Toolkit (2025); Code §11-28-200.

Statewide floor

Senate Bill 284, Utah Code §10-21-304, has been in effect since October 1, 2026. Every city on this list must allow a detached ADU as a permitted use — not a conditional use — on a lot of 11,000 square feet or larger that already has a permitted single-family house. A city may also allow one on a smaller lot. It may still set size, height, coverage, setbacks, and owner occupancy, and it may require that the unit not be larger than the house, not sit in the front yard, and not be rented for fewer than 90 days. Parking may not exceed one stall under 650 square feet, or two stalls at 650 square feet and above. A printed ban, or a conditional-use requirement, on a qualifying lot conflicts with the statute even if the code book is late. Confirm the city’s ordinance before anyone draws.

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