You’ve stood in the back corner of the yard where the shed is and run the numbers in your head. A small unit back there. A rental. An office that isn’t the guest room with a desk shoved in it. A place for someone in your household who needs their own door.
For years the answer in most Utah cities was some version of no, or an approval process long enough that most people quit halfway through. That has changed in a lot of places, and it’s still being worked out in the rest.
Short answer: Utah cities are now required to allow detached accessory dwelling units on many single family lots of 11,000 square feet or larger. Cities still set their own setbacks, height limits, parking rules, and owner occupancy requirements, so what you can actually build comes down to your city’s current ordinance.
Here’s how to find out where you stand.
What actually changed
An accessory dwelling unit is a second, smaller home on a lot that already has a house on it. Utah code splits them into two types, and the distinction matters more than almost anything else here.
An internal ADU lives inside the existing home. A basement apartment with its own entrance is the classic version. Those have had statewide protection for a while, which is why basement units are common along the Wasatch Front. We covered how that statute works in our guide to Utah ADU laws in 2026.
A detached ADU is the freestanding one. The backyard cottage, the casita, the apartment over a garage. Until this year, whether you could build one was almost entirely a city by city question, and in many cities the answer was no.
Now there’s a statewide floor. On single family lots at or above 11,000 square feet where single family homes are a permitted use, cities generally have to allow a detached unit. Cities also lost the ability to require a conditional use permit, and they can no longer cap the size below the size of the primary home.
Cities kept plenty. Setbacks, height, utility connections, design standards, short term rental limits, and in many places owner occupancy are still local decisions.
So can I just go build one?
No, and that’s the part people skip. A statewide floor is not a permit.
Here’s what that looks like in practice. Lehi’s detached ADU code amendment drops the city’s detached lot minimum from 14,520 square feet to 11,000, keeps the ability to require two off street parking spaces for a unit over 650 square feet, and replaces its old 1,300 square foot size cap with the rule that the unit simply has to be smaller than the main house.
Draper’s ADU permit page lists a detached minimum lot size of 12,000 square feet, a size limit of 50 percent of the primary dwelling, a 35 foot height cap, owner occupancy, one additional parking space, no separate utility meters, and a 30 day minimum lease.
Two cities, twenty minutes apart, meaningfully different rules. And city pages don’t all update the week an ordinance changes, which is exactly why you call rather than assume.
How to find out what your city allows
Do these four things, in this order.
Confirm your lot size and zone. Your county assessor’s parcel page has the square footage and your city’s zoning map has the district. Both are free and online. Under 11,000 square feet, the statewide detached standard may not reach you, and you’re back to whatever your city allows on its own.
Read the city’s ADU page before you call. Most Wasatch Front cities have one. Salt Lake City’s ADU information page is a thorough example, with a planning handbook and pre reviewed standard plans ranging from a 650 square foot one bedroom to a second story garage conversion. Provo’s ADU page lays out its owner occupancy requirement, rental dwelling license, and fees.
Check whether you’re in a city at all. Unincorporated county is a different rulebook. Salt Lake County’s ADU page sets 7,000 square feet as the detached minimum in most zones, requires 10 feet from the rear property line and 6 feet from the main house, and requires owner occupancy of one of the two units.
Then call planning. Not a builder first. Planning first.
The questions to ask when you call
Write these down and get answers to all of them before you spend money on a design.
- Is my parcel eligible, and under which section of the code?
- What are the setbacks from the rear line, the side lines, and the main house?
- What is the height limit, and is it measured to the peak or the eave?
- How many parking spaces, and can they be tandem?
- Is owner occupancy required, and of which unit?
- Is there a maximum size, and is it a flat number or a percentage?
- Are separate utility connections required, and what are the tap and impact fees?
- Are short term rentals allowed, and is there a minimum lease term?
Then ask your HOA the same questions. A city can permit something your covenants still prohibit.
The honest costs and complications
A detached unit is a small house. It gets a foundation, a roof, plumbing, electrical, HVAC, and its own inspections. Utility connections and impact fees can be a meaningful share of the total, and they vary widely by city and by whether there’s capacity at the street.
Financing is its own conversation. A construction loan, a cash out refinance, and a home equity line all behave differently, and the right answer depends on your rate, equity, and timeline. Talk to a loan officer before you assume a number.
Resale is genuinely mixed. A permitted, code compliant unit with a rental history is a documented feature an appraiser can work with. An unpermitted one is a problem that surfaces mid sale at the worst possible moment. If you build, build it permitted.
And it changes how you live on your lot. Less yard, a shared driveway, and a second front door twenty feet from your kitchen window.
Before you commit, it’s worth knowing what your property is worth as it sits. A home value report is a reasonable starting point, and if you’re weighing building against moving, our buying page is the other half of that comparison.
Frequently asked questions
Can I build a detached ADU on any lot in Utah? No. Utah’s statewide standard generally applies to single family lots of 11,000 square feet or larger in areas where single family homes are a permitted use. Smaller lots fall back to local rules, which vary by city. Confirm eligibility with your city’s planning department before making plans.
What’s the difference between an internal and a detached ADU? An internal ADU is built inside the existing home, such as a basement apartment with its own entrance. A detached ADU is a separate structure on the same lot, like a backyard cottage or a unit above a detached garage. Utah regulates the two under different standards.
Do Utah cities require owner occupancy for an ADU? Many do, but not all, and the requirement can apply to either the main home or the unit. Salt Lake County requires owner occupancy of one of the two dwellings in unincorporated areas, with limited exceptions. Check your specific city or county ordinance.
How much parking does a detached ADU need in Utah? It depends on the city and the size of the unit. Some Utah cities can require up to two off street spaces for a detached unit over 650 square feet, while others require one additional space. Your city’s planning department can confirm the current requirement.
Does an ADU increase my property taxes? Adding a permitted dwelling unit generally changes your assessed value, which can affect your tax bill. The specifics depend on your county assessor’s process and your property’s classification. A tax professional or your county assessor’s office can tell you how it would apply to you.
The bottom line
The door is open wider than it was a year ago. It is not the same width in every city, and it is still being measured in a few of them.
So treat this as a research project before it becomes a construction project. Parcel size, zone, setbacks, parking, owner occupancy, fees, HOA. One afternoon of questions and you’ll know whether the corner of your yard is a project or a daydream.
And when it does come time to sell, what you pay to sell matters. On a $640,000 Salt Lake County home, the UtahRealEstate.com single family median in August 2026, a 3 percent listing fee runs $19,200. Homie’s flat fee is $6,000, with the same licensed agent, the same MLS exposure, and the same representation.* The full breakdown is on our pricing page.
Whether you’re buying, selling, or doing both, Homie has your back.
— The Homie Team
*All brokerage fees, including listing and buyer agent compensation, are fully negotiable and determined solely by the seller and service provider.
*Flat-fee pricing and service availability may vary by location.
*Examples and potential savings are for illustrative purposes only.
*Market data from UtahRealEstate.com Monthly Local Market Reports, August 2026. All data obtained from sources deemed reliable but not verified. Information not guaranteed.