Start with the answer because it is short. The Condominium Ownership Act says nothing about accessory dwelling units. The phrase "accessory dwelling" does not appear anywhere in Chapter 8. A unit owner in a Utah condominium has no statutory right to build one or to rent it out.

The Gap Is Structural, Not an Oversight

This is worth understanding because it explains why the gap is unlikely to close by accident. The condominium ownership act does not define an internal accessory dwelling unit. It borrows the definition from the land use statutes, Section 10-21-101 for cities and Section 17-80-101 for counties.

Under that definition, it does not apply to a condominium. An internal accessory dwelling unit must be created "within a primary dwelling" and "within the footprint of the primary dwelling" as it stands at the time. A "primary dwelling" is, in turn, defined as a single-family dwelling that "is detached" and "is occupied as the primary residence of the owner of record." And an “accessory dwelling unit” is defined as a habitable living unit "added to, created within, or detached from a single-family dwelling and contained on one lot or parcel."

A unit in a condominium building is not a detached single-family dwelling, and it does not sit on its own lot or parcel. The thing the statute protects is defined in terms that a condominium unit does not meet. That is a definitional result rather than a policy judgment about condominiums.

One consequence follows immediately. Whether any particular property qualifies is a land-use question for your city or county, not one your association or this Office decides.

What You Do Have: A Limit on Your Declaration

Chapter 8 is not silent about the inside of your unit. Section 57-8-10(9) lists what a declaration and any amendment to it may not do, and two entries matter here.

Under Subsection (9)(n), a declaration may not "impose a restriction on a unit interior, except as reasonably necessary for the safety of adjacent units and the occupants of the units." Under Subsection (9)(k), it may not "interfere with reasonable activity of a unit owner within the confines of the unit, to the extent that the activity is in compliance with local laws and ordinances, including nuisance laws and ordinances."

Read both limits carefully before relying on either. Neither mentions accessory dwelling units, nor does it create a right to build anything, and both carry qualifiers that do real work. Whether a specific provision of your declaration is "reasonably necessary for the safety of adjacent units" is a judgment about your governing documents.

Combining Two Units Is a Different Question, and the Statute Answers It

Owners who want more living space in a condominium usually reach the same practical question by another route: buying next door. Section 57-8-4.5 addresses that directly. Subject to the declaration, a unit owner who has acquired an adjoining unit sharing a common wall may remove or alter the partition between them, "even if the partition is entirely or partly common areas and facilities," or create an aperture between them.

Three limits apply. The work may not impair structural integrity or mechanical systems, may not reduce support for the common areas or another unit, and may not violate a land use ordinance or building code. The management committee may require you to pay for a registered engineer's or architect's opinion confirming the first two.

Separately, Section 57-8-9 is stricter than most owners expect. No unit owner may do work that would "jeopardize the soundness or safety of the property, reduce its value or impair any easement or hereditament" without first obtaining "the unanimous written consent of all the other unit owners."

If You Submit Plans

Two protections apply to any construction or improvement plan your association must approve. Under Section 57-8-6.7, the association may not charge a plan fee exceeding the actual cost of review, and a denial must be in writing and must specify "each governing document provision on which the association relied," together with the specific aspect of the plan that does not conform to it. A denial that merely states the committee voted no does not meet that standard.

Where to Go Next

Two different offices answer three different pieces of this. Whether an additional dwelling may exist at the property at all is decided by your city or county land use authority. Whether the association complied with the statute when charging a plan fee or denying a plan is a question the Office can help with.

Ask the management committee in writing before you begin work, and keep the answer. It costs nothing, and it is the single most useful thing an owner can do in this area.

Reviewed against the Utah Code, current as of August 12, 2026.