The New Utah Law That Could Add a Second Home to Your Lot

Imagine looking out your back window at a small home that could house a parent, a grown kid, or a renter paying you every month. For a lot of Utah homeowners, that picture just got a lot more possible. A new state law that took effect October 1 changes what cities can say no to, and it could add real value to certain lots. Here is what it actually says, what it does not say, and how to find out if your property qualifies.

What Is the New Utah Detached ADU Law

An ADU is an accessory dwelling unit, a second small living space on the same property as the main house. Some are inside the home, like a basement apartment. A detached ADU, sometimes called a DADU, is a separate building in the yard, like a backyard cottage or an apartment above a detached garage.

Senate Bill 284, passed in the 2026 legislative session and codified in Utah Code 10-21-304, limits how much cities can restrict detached ADUs. Cities had until October 1 to update their rules, and the law is now in effect. The idea behind it is simple. Utah needs more housing, and letting homeowners add a unit on land they already own is one way to do it without building a new subdivision.

Which Lots Qualify Under the New Law

The main rule is lot size. In the cities the law covers, a detached ADU has to be allowed on lots of 11,000 square feet or larger that already have a single-family home on them. That is roughly a quarter of an acre. Cities can choose to allow them on smaller lots too, but the state requires it only at 11,000 square feet and up.

The law applies to what it calls specified municipalities, which means the larger cities and the bigger fifth class cities in the state's more populated counties. If you live in a smaller town, your rules may be different. The quickest way to know is to call your city planning department and ask whether detached ADUs are allowed on your lot under the new code.

What Can Cities No Longer Do

Before this law, many cities either banned detached ADUs outright or made homeowners go through a long conditional use process where neighbors could object and the city could say no. The new law takes that away in primarily residential zones. A city cannot treat a qualifying detached ADU as a conditional use.

It also limits parking demands. A city cannot require more than two on site parking spaces for a detached ADU that is 650 square feet or larger, and no more than one space for a smaller unit. And the building has to meet normal building codes, so this is not a loophole around safety rules.

What Can Cities Still Require

This is the part that surprises people. The state did not hand homeowners a blank check. Cities still have a lot of say over the details, and they are using it.

A city can keep a detached ADU out of the front yard. It can say the ADU cannot be larger than the main house. It can limit a lot to one ADU. It can ban rentals shorter than 90 consecutive days, which means no Airbnb style short term rentals in many places. It can require the owner to live in either the main house or the ADU. And all of the regular rules on height, lot coverage, and setbacks still apply.

So the honest summary is that the law opens the door, but each city decides how wide it opens.

What Are Utah County Cities Doing About It

Cities across Utah County have been scrambling to update their codes. Lehi already allowed detached ADUs on lots of at least 14,520 square feet, capped at 1,300 square feet. Under its updated policy, the ADU has to sit at least six feet from the main home, and the owner has to live in either the main home or the ADU. A city official estimated the number of eligible lots could go up by as much as 20 percent.

Orem did not allow detached ADUs before. Its proposed policy keeps them out of front yards and prohibits short term rentals. Provo previously allowed them only in certain overlay zones, and the city has been working on how to apply the new rules, including a proposal to limit total accessory structures on a lot to 40 percent of the parcel.

Because these rules keep changing, always confirm with your city before you spend a dollar on plans. Salt Lake City has its own long standing ADU program too. Detached units there can be up to 1,000 square feet and no larger than the main building, with owner occupancy required, and the city has offered a pilot loan program for certain properties west of I-15.

What Could a Second Home on Your Lot Be Worth

I want to be careful here, because I do not want anyone to think an ADU is automatic money. Building one costs real money, and it varies a lot depending on size, finishes, utilities, and your lot. Rental income, a higher property value, and extra tax or insurance costs all depend on your situation. Run the numbers before you commit.

That said, there are a few reasons an ADU can be worth looking at. Rental income can help with your mortgage or build savings. It can give family a place close by, like an aging parent or a young adult who is not ready to buy yet. And a lot with legal ADU potential may be more attractive to some buyers down the road. If you are thinking about the value of your home today, you can start with a free estimate at danarealtorutah.com/evaluation.

What If You Want to Buy a Home With ADU Potential

If you are a buyer, this law adds a new question to your list. Does this lot have room for an ADU, and would the city allow one? Look for lots of 11,000 square feet or more, with a flat usable backyard, access for utilities, and no HOA that bans accessory units. HOAs and recorded covenants can still restrict what you build, and the state law does not automatically override them, so read those documents carefully.

Be careful about buying purely on the promise of future ADU income. Ask the city what is allowed today, get realistic cost estimates from a builder, and talk to a lender about how future rental income may or may not count. Financing is a separate conversation. My post on getting pre-approved in Utah explains what lenders look at today, and it is a good place to start.

Have a unit you want to build? Talk to a local engineer too, because Utah snow loads and seismic requirements matter for any new structure.

What If You Are a Homeowner Thinking of Selling

If your lot is large, the new law might give you a selling point you did not have last year. Buyers who want multigenerational living or rental income may pay attention. But I would not promise buyers anything an ADU cannot deliver. The best approach is to know what the city allows, document it, and present it honestly.

If you are getting ready to list, my post on how to prepare your Utah home for sale covers what to do first. And if you already have an unpermitted basement apartment or backyard structure, talk to me before you list. Unpermitted units can cause trouble with lenders and appraisals.

What I Tell Clients About Second Homes on a Lot

I have been in Utah real estate for a long time, and I have seen the same story many times. A family needs more space, whether it is for a parent, a college student, or a little extra income, and they think the only answer is to move. Now some of them have another option. What I tell my clients is to slow down and check three things first: your lot size, your city's rules, and your real budget. If all three line up, an ADU can be a great move. If not, you will have saved yourself a lot of money and stress. I am happy to look at your address with you and tell you what I know, and for my Spanish speaking families, I am glad to walk through all of it in Spanish.

Frequently Asked Questions

What is the new Utah ADU law

Senate Bill 284 limits how cities can restrict detached accessory dwelling units. In covered cities, a detached ADU must be allowed on single family lots of 11,000 square feet or larger, and it cannot be treated as a conditional use in primarily residential zones.

When did the new Utah ADU law take effect

Cities had until October 1, 2026 to update their rules, and the law took effect on that date. Some cities are still finalizing details, so check with yours.

Can I rent out my detached ADU in Utah

In most cases yes, but cities can ban rentals shorter than 90 consecutive days and can require the owner to live on the property. Check your city rules before you plan on rental income.

Does my HOA have to allow a detached ADU

Not necessarily. The state law limits what cities can require, but HOA rules and recorded covenants can still restrict accessory units. Read your HOA documents before you plan anything.

How much does it cost to build a detached ADU in Utah

It depends on size, finishes, utilities, and your lot, so get quotes from local builders before you decide. Also factor in permit fees, possible utility upgrades, and changes in property taxes and insurance.

If you want help figuring out whether your lot might qualify, or you want to find a home with ADU potential, call or text me at 801-636-3609. You can browse homes on my website.