What Utah's New ADU Rules Mean for Salt Lake County Homeowners

As of October 1, 2026, Utah's larger cities must allow a detached accessory dwelling unit, a small separate home in the backyard, on single-family lots of 11,000 square feet or more. For Salt Lake County families, that can mean room for aging parents, a place for an adult child, or rental income, without selling the house you already love. Your city still sets most of the details, so your first call is to its planning office.

At GR Homes, we serve families who want to stay close and keep the home they have. Here's what changed, and what didn't.

What exactly changed in Utah's ADU law?

The Utah Legislature passed S.B. 284 in the 2026 General Session. Part of it created Utah Code 10-21-304, which requires covered cities to permit a detached ADU on any lot of 11,000 square feet or more with a single-family home, where a single-family home is an allowed use.

An ADU (accessory dwelling unit) is a complete, separate living space on the same lot as a main home. A detached ADU sits in its own building, like a backyard cottage or a converted garage. Internal ADUs, like a basement apartment, were already a permitted use in primarily residential zones. Now the backyard has a path too.

Does the new rule apply to my city?

It applies to what state law calls a "specified municipality." In general, that means cities with 5,000 or more residents in Utah's larger counties, which include Salt Lake County. A city can also choose to allow detached ADUs on lots smaller than 11,000 square feet.

In unincorporated Salt Lake County, county rules apply instead. The county updated its ADU ordinance in 2024 and allows detached ADUs on lots of at least 7,000 square feet in most zones.

What can my city still decide?

A lot. The state set a floor, not a blueprint. A city can:

• Set limits on size, height, setbacks, and lot coverage, and require a design that matches the main home.
• Keep the ADU out of the front yard and off recorded easements.
• Require the owner to live in the main home or the ADU.
• Prohibit rentals shorter than 90 consecutive days.
• Allow only one ADU per lot.
• Say no if water, sewer, power, or storm drain service can't support it.

A city can't require a conditional use permit in a primarily residential zone. It can't require more than two parking spaces for an ADU of 650 square feet or more, or more than one for a smaller unit. Cities must also offer a way to convert a legally built accessory structure, like a detached garage, into an ADU, and every ADU must meet building, health, and fire codes.

Who is this change really for?

Families. A backyard home can give a parent their own front door, close enough that you can help while they keep their independence. It can give an adult child a place to save before buying. And where your city allows renting, it can bring in income that helps carry your monthly mortgage payment.

For many households, three generations near one kitchen table isn't a trend. It's home.

What should I check before I plan one?

1. Your lot size. Your county property record lists it.
2. Your city's ADU rules. Ask the planning office whether your lot qualifies and what standards apply.
3. Your HOA. If you have one, read the CC&Rs, the neighborhood's recorded rules.
4. Utilities. Ask whether water and sewer service can support another unit.
5. The full cost. Get real bids. Ask how a new unit could change your property taxes and insurance.

How would I pay for an ADU?

Some families pay cash. Others borrow. Before you sign with a builder, ask a licensed lender to compare the new payment and rate against the mortgage you have now.

Top Level Home Loans, an independent mortgage company we work with, can run those numbers at toplevelhomeloans.com. You're not required to use them. Any licensed lender can do this. GR Homes is the real estate brokerage. Top Level is the mortgage company. They're two separate businesses.

What's a simple next step?

Call your city's planning office and ask: Does my lot qualify for a detached ADU, and what are your rules?

For a closer look at what an ADU is, what the new law changed, and how to tell if your property might qualify, download our Gomez Rueda Realty Group ADU Guide 2026. If an ADU is part of a bigger decision, like selling or buying a home on a larger lot, we also have more GR Homes guides. If you'd rather talk it through, we're here.

FAQ

Can I build a backyard home in Salt Lake County now? Possibly. Since October 1, 2026, larger Utah cities must permit a detached ADU on single-family lots of 11,000 square feet or more. Your city sets the details.

Do I have to live on the property? Your city may require the owner to live in the main home or the ADU. Unincorporated Salt Lake County requires it.

Can I use my ADU as a short-term rental? A city may prohibit renting a detached ADU for less than 90 consecutive days. Check your city's rules first.

Do I need a permit to build an ADU? Expect one. Every ADU must meet building, health, and fire codes.