Toolkit Topic

Accessory Dwelling Unit (ADU) Model Ordinance

This model ordinance is a featured item in our Local Government Toolkit.

  1. Definition. An accessory dwelling unit (ADU)—also known as a mother-in-law apartment, accessory apartment, basement apartment, etc.— is defined in Utah code to mean “a habitable living unit added to, created within, or detached from a primary single-family dwelling and contained on one lot.”
  2. Permitted Use. ADUs, both internal to and detached from a primary single-family dwelling, are a permitted use in all residential zones, provided the ADU meets all of the following criteria:
    1. All construction and remodeling related to the ADU shall comply with building codes and ordinance requirements in effect at the time of construction or remodeling—including Utah state code section 10-9a-511.5, changes to dwellings – egress windows;
    2. Meet any other requirements of the residential zone;
    3. Provides areas for eating, sleeping and sanitation facilities separate from the principal dwelling unit;
    4. Is not intended for sale or detached by deed and shall only be rented;
    5. Interior access between the main living area of the principal dwelling unit and an internal ADU must be maintained, unless sufficient means of egress have been determined during an inspection by the fire department;
    6. Sufficient parking is provided for any vehicles used by those residing in the primary dwelling and the ADU. Sufficient parking means that all vehicles can park off-street or, if applicable, on that part of the street which immediately abuts the lot of the primary dwelling.
    7. A detached ADUs total square footage shall be less than the primary dwelling.

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