Effective 10/1/2026
10-21-304 Detached accessory dwelling units.
(1)
(a)A specified municipality shall adopt a land use regulation that permits a detached accessory dwelling unit on any lot or parcel that is 11,000 square feet or larger and contains a single-family dwelling, if the single-family dwelling is a permitted use on the lot or parcel.
(b)This section does not prohibit a municipality from adopting a land use regulation that permits a detached accessory dwelling unit on a lot or parcel that is smaller than 11,000 square feet.
(2)A land use regulation described in Subsection (1) shall:
(a)require that a detached accessory dwelling unit comply with all applicable building, health, and fire codes; and
(b)include a process for the owner of a legally constructed accessory structure to convert the accessory structure to a detached accessory dwelling unit subject to applicable:
(i)dwelling and accessory structure setback requirements; and
(ii)building, health, and fire codes.
(3)A land use regulation described in Subsection (1) may not:
(a)require a conditional use permit for a detached accessory dwelling unit if the proposed detached accessory dwelling unit is located in a primarily residential zone;
(b)require more than two on-site parking spaces assigned to a detached accessory dwelling unit that is 650 square feet or larger;
(c)require more than one on-site parking space assigned to a detached accessory dwelling unit that is smaller than 650 square feet; or
(d)include design standards for a detached accessory dwelling unit that conflict with Section 10-20-618.
(4)A land use regulation described in Subsection (1) may:
(a)require a detached accessory dwelling unit to:
(i)conform to applicable land use regulations that regulate structure size, dimension, height, and maximum lot coverage;
(ii)conform to setback requirements, that may take into account proximity to property lines and other structures, easements, window orientation, massing, or other elements; and
(iii)be designed consistent with the design of the single-family dwelling;
(b)prohibit a detached accessory dwelling unit from being:
(i)larger in size than the single-family dwelling located on the same lot or parcel;
(ii)located within a public utility easement or other recorded easement;
(iii)located in a front-yard area of a lot or parcel; or
(iv)rented for less than 90 consecutive days;
(c)require that the owner of a lot or parcel where a detached accessory dwelling unit is located reside in the detached single-family dwelling or detached accessory dwelling unit located on the lot or parcel;
(d)require that when a detached garage is converted to a detached accessory dwelling unit, any parking spaces required for the single-family dwelling that were located within the detached garage are replaced on-site;
(e)prohibit more than one accessory dwelling unit on a lot or parcel; and
(f)prohibit a detached accessory dwelling unit if:
(i)the detached accessory dwelling unit will not have adequate access to a required utility service that is a project improvement, including sanitary sewer, culinary water, electrical, or storm water; or
(ii)a utility service that is a system improvement, including sanitary sewer, culinary water, electrical, or storm water, to which the detached accessory dwelling unit is required to connect does not have sufficient capacity to support the addition of the detached accessory dwelling unit to the utility service system improvements.
(5)This section does not supersede:
(a)a land use regulation that regulates a detached accessory building that is not a detached accessory dwelling unit;
(b)prohibitions or restrictions on detached accessory dwelling units in a development agreement signed by a municipality on or before May 6, 2026; or
(c)a land use regulation or administrative action that:
(i)is not prohibited by law; and
(ii)relates to a detached accessory dwelling unit.

Enacted by Chapter 166, 2026 General Session