ADU rules in Murray

Detached ADUs are allowed with an administrative ADU permit on properties where a single-family home is a permitted use, but only on lots of at least 10,000 sq ft ("The minimum lot size required for construction of a detached ADU in all single-family residential zones shall be ten thousand (10,000) square feet"). The unit is limited to one story and 20 ft or the height of the house, whichever is less, may not sit in the front yard, and needs 10 ft rear and side setbacks (20 ft on a corner side). An existing accessory building such as a detached garage may be converted only if it already meets those setbacks. Utah Code 10-21-304, in force since 10-1-2026, requires cities like Murray to allow a detached ADU on any single-family lot of 11,000 sq ft or more; Murray's 10,000 sq ft minimum already goes further, and no alignment amendment had been proposed through October 2026.

Attached ADUs (a unit within or incorporated into the single-family house) are allowed with an administrative ADU permit on properties that allow single-family dwellings as a permitted use. Only one ADU is allowed per lot, a separate entrance may not face the front yard (it must be on the side or rear), and separate utility meters for the ADU are prohibited. Additions built for the unit must stay within the zone's lot coverage and setbacks. State law (Utah Code 10-21-303) separately makes an internal ADU a permitted use in primarily residential zones.

A detached ADU must be smaller than 50% of the primary residence's square footage and may never exceed 1,000 sq ft ("The total area of the ADU shall be less than fifty percent (50%) of the square footage of the primary residence and in no case shall exceed one thousand (1,000) square feet"); the whole detached structure containing the ADU is also capped at 1,000 sq ft. Attached ADUs have no stated floor-area cap and are limited instead by the zone's lot coverage and setbacks. Utah Code 10-21-304(4) lets cities set size limits like these.

The owner (a titleholder or contract purchaser) must live in either the main house or the ADU as their permanent residence and may not collect rent for the unit they occupy. Applicants sign an owner-occupancy affidavit that is recorded against the property, and if the owner stops living on site the ADU must be vacated right away and the property converted back to a single-family home. Utah Code 10-21-304(4)(c) expressly allows this requirement for detached units.

One off-street space is required in addition to the main home's parking, with three off-street spaces in total on the property ("In addition to the parking required for the primary unit, one (1) additional off street parking space shall be provided. A total of three (3) off street parking spaces shall be provided"). Occupants' vehicles must park on site, with street parking reserved for visitors. The same standard applies to attached and detached ADUs, and one space per ADU is within the state caps in Utah Code 10-21-304(3) (no more than one space for a detached unit under 650 sq ft, two at 650 sq ft or more).

An ADU that meets the chapter's standards "may be allowed in any zone that allows for single-family housing as a permitted use after approval of an accessory dwelling unit permit by the Community and Economic Development Director or their designee": an administrative staff approval, not a conditional use hearing. A building permit and inspection follow before a certificate of occupancy is issued. This matches Utah Code 10-21-304(3)(a), which bars a conditional use permit for detached ADUs in primarily residential zones.

By applying for an ADU the owner agrees that neither the main home nor the ADU will be used as a short-term rental, defined as renting all or part of the property for less than 30 days at a time. A residential rental business license is required to rent out either unit. The city may record a lien of up to $100 a day for uncured violations after notice and an opportunity for a hearing.