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Accessory Dwelling Units (ADUs)

What is an ADU?

An Accessory Dwelling Unit (ADU) is a self-contained residential unit located on the same lot as a single-family home. ADUs may be:

  • Internal (within the main home) 
  • Detached (in a separate structure on the same lot)

Accessory Dwelling Units (ADUs), also known as in-law suites, basement apartments, or granny flats, have long been part of neighborhoods as flexible housing options. These smaller, self-contained residential units are located on the same lot as a single-family home and can help increase housing supply within existing neighborhoods.

On June 4, 2024, Salt Lake County adopted an ordinance to reduce restrictions to facilitate greater ADU adoption by residents. This webpage is a general guide to help you determine eligibility, understand requirements, and navigate the permitting process.  

Note: Each application is subject to specific zoning and site conditions. This guide does not replace official code or permit review.

Resources

Eligibility Criteria

You may be eligible to build or convert an ADU if:

  • Your property is zoned residential (including R, A, Forestry, or PC zones)
  • Your property is a single-family detached residence (not a townhome or part of a PUD)
  • You meet all setbacks, parking, lot coverage, and design requirements.
  • For internal ADUs: Your lot must be at least 6,000 sq. ft
  • For detached ADUs: Your lot must be at least 7,000 sq. ft., except in the PC Zone, where detached ADUs may be allowed on 6,000 sq. ft. lots

(§19.15.030)

Requirements Include:

Internal ADUs:

  • Same setbacks as a single-family dwelling in the zone. 

Detached ADUs:

  • Must be at least 10 feet from the rear property line and 6 feet from the main house.
  • Side yard setbacks depend on zoning and public utility easements
  • Conversions of older structures must comply with the accessory structure setbacks in place at time of original construction.
  • Noncomplying structures (per §19.88.150) may qualify for exceptions

(§19.15.050)

In addition to the required parking for the existing home, the property owner must demonstrate that at least one on-site parking space is available for the ADU.


(§19.15.060)

Detached ADUs can be up to 20 feet tall or match the height of the main home depending on their setbacks. 


(§19.15.070)

Lot and rear yard coverage must meet the requirements of your zoning district.


(§19.15.080)

  • The primary dwelling or the ADU must be owner-occupied
  • Short exceptions of up to 2 years may apply for military deployment, medical services, or religious missions.

(§19.15.090)

  • Only one ADU per lot is permitted (internal or detached).
  • ADUs cannot be sold or subdivided into separate lots.

  • Water and sewer availability must be confirmed. 
  • Internal ADUs cannot have separate utility meters.
  • Detached ADUs may be separately metered so long as the property owner receives the bills for both units. 

(§19.15.140)  

Before renting, you must:

  • Record an affidavit showing owner occupancy.
  • Obtain a business license for the rental unit. 

(§§19.15.120–130)

ADU Design & Construction Standards

  • A building permit is required before constructing or converting to an ADU.
  • All ADUs must comply with applicable building, fire, and health codes.
  • Written confirmation from your water provider must be submitted before a permit can be issued.
  • ADUs must have a separate address marker for mail and emergency response.

  • Be constructed on a concrete slab (unless above a garage)
  • Not be built on a basement, piers, or any mobile or temporary foundation
  • Not be located in the front yard or corner lot side yard, unless the lot is at least 1 acre and the ADU is 30 ft from the front lot line
  • Be set back 10 ft from the front facade of the primary dwelling
  • Include proper roof drainage and stormwater controls
  • Single-family homes with a detached ADU must maintain the appearance of a single-family residence.

  • Meet safety and egress codes (e.g., window wells)
  • Provide adequate heating and ventilation

These do not require separate HVAC or firewalls.

How to Apply for an ADU

  • Before applying, reach out to Planning & Development to confirm your zoning and check if your property is eligible for an ADU.
  • Phone Number: (385) 910-5600

  • Go to the City Works Portal

  • You’ll need an account to submit your application.

  • Click “New Application”
  • Select “Building”
  • Choose “Residential”
  • Select “Residential Accessory Dwelling Unit (ADU)”

  • Follow the prompts to enter your property and project information.

  • Site plan (showing where the ADU will be located on your lot)
  • Floor plan (layout of the ADU)
  • Proof of owner occupancy 
  • Letter of confirmation from your water provider 

  • Review everything carefully, then submit. You’ll get updates and requests for any additional info through City Works