Last verified: July 2026 · Utah ADU Builders editorial team
Utah ADU Statistics: What the Numbers Actually Show (2026)
Utah ADU statistics are surprisingly hard to pin down — the state does not publish a single official count of accessory dwelling units (ADUs), so any exact "number of ADUs in Utah" you see online is an estimate. What the verified data does show is clear: ADU activity is rising but growing slowly, the most reliable numbers are city-level rather than statewide, and cost and site conditions — not just the law — decide how many units actually get built. This page is for homeowners, researchers, and journalists who want to understand what the data actually says rather than repeat a figure without knowing where it came from.
About this page. Utah ADU Builders is a Utah-focused ADU planning, feasibility, and builder-matching resource. We are not a city, a government office, a law firm, a lender, an architect, an engineer, or a licensed contractor. We may receive compensation when homeowners request estimates or are connected with local professionals, but that does not change how we explain Utah's ADU rules, the data, or the risks. Local verification is always required before you rely on any rule or figure here.
What we checked for this page
- Utah state ADU law — internal ADUs (Utah Code §10-21-303) and the 2026 detached-ADU law (Senate Bill 284, which enacts §10-21-304), via the Utah Legislature and the Utah Office of the Property Rights Ombudsman.
- Salt Lake City ADU figures, from the city planning department's official 2022 ADU Annual Report.
- How Utah cities report ADUs, via the state's Moderate Income Housing reporting framework (Utah Department of Workforce Services / Housing and Community Development).
- The statewide housing dataset, via the Utah Geospatial Resource Center's Housing Unit Inventory.
- National ADU context, via Freddie Mac, the Federal Housing Finance Agency, the Mercatus Center, and John Burns Research & Consulting.
Full sources are listed at the end. Where reliable data doesn't exist, we say so rather than estimate.
How many ADUs are in Utah?
There is no official statewide total of completed, legal ADUs. Utah's main housing dataset tracks ADUs in only one county, building permits don't cleanly separate ADUs from other construction, and official counts miss units that were never permitted. The most trustworthy numbers come from individual cities — and even those aren't directly comparable.
A quick definition first: an ADU (accessory dwelling unit) is a self-contained second home on the same lot as a primary house. In Utah that usually means one of three things — a basement or internal unit carved out of an existing home (like a legal basement apartment), a unit attached to the house with its own entrance, or a detached backyard cottage or unit above a garage.
Here's why a single "Utah ADU count" doesn't exist:
The statewide housing dataset only counts ADUs in one county. Utah's authoritative parcel-level housing dataset, the Housing Unit Inventory (maintained under Utah Code 63A-16-506), does include a "single family with accessory dwelling units" category — but currently only for Salt Lake County, and it specifically excludes ADUs elsewhere in the state. It's a useful signal, not a complete statewide count.
Building permits are a blunt instrument. ADU work often shows up mixed in with remodels, additions, and basement finishes, so permit totals rarely break out "ADU" cleanly on their own.
Some of Utah's ADUs are invisible on paper. Basement and mother-in-law apartments have existed in Utah neighborhoods for generations. Official counts capture units a city knows about through permits, registrations, or licenses — they may not capture units that were never permitted, registered, or licensed.
What counts as an "ADU statistic" — and why it matters
Before you trust any ADU number, check what it actually measures. A building permit is not a finished unit, a rental license is not new construction, and one city's registration count is not comparable to another city's permit count. These distinctions are the single biggest reason ADU statistics get misreported.
| The number you're reading | What it can tell you | What it does not tell you |
|---|---|---|
| Building permits issued | A city approved construction or a conversion | Whether the unit was ever finished or occupied |
| Completions / certificates of occupancy | A unit actually reached the finish line | Whether it's rented, affordable, or occupied |
| Rental business licenses | A city recorded or authorized a rental use | Whether anything new was built (it may be an existing unit) |
| ADU registrations | A city formally recognized an ADU | That another city counts the same way |
| Applications received | Homeowner interest and demand | How many will clear review or get built |
| A "statewide" number in the news | Useful directional context | A verified, official total — Utah doesn't keep one |
Keep this table in mind as you read the rest of the page. Every figure below is labeled with what it measures and when it was reported.
What Salt Lake City's numbers show (the clearest picture in Utah)
Salt Lake City has tracked ADUs since it legalized them citywide in 2018, which makes it the best available window into real Utah adoption. The pattern is consistent: slow but steady growth, with cost repeatedly named as the main obstacle — not the rules.
The start was slow. In the first full year after the 2018 citywide ordinance, the city recorded just three completed ADUs and six building permits, according to city figures reported by Building Salt Lake.
Growth has been gradual but real. The city's 2022 ADU Annual Report — the most recent published — counted 170 ADU building-permit applications cumulatively from 2018 through 2022. Of those, 44 were completed, 36 were under construction, 49 were in building-permit review, and 41 had been withdrawn. Separately, the city processed 86 conditional-use ADU applications from 2019 through 2022.
The units are small. Salt Lake City's ADUs have averaged roughly 570 square feet, typically a one-bedroom, and about 14.5 feet tall — under what zoning even allows.
Applications aren't being denied — they complete, proceed, or get withdrawn. The city's reporting has no "denied" category; units move through review, and a share of applications are withdrawn along the way.
Cost is the barrier, not legality. The annual report itself notes it doesn't track construction cost, which residents call a major obstacle. In 2022 local reporting, a Utah ADU builder estimated that city impact fees and permits added roughly $10,000–$12,000 to a project — among the highest in the country — and Salt Lake City has since reduced its ADU impact fees by treating them more like apartments than stand-alone homes.
| Salt Lake City ADU snapshot | Figure | As of |
|---|---|---|
| ADU building-permit applications, cumulative 2018–2022 | 170 total | 2022 report |
| — Completed | 44 | 2022 report |
| — Under construction | 36 | 2022 report |
| — In building-permit review | 49 | 2022 report |
| — Withdrawn | 41 | 2022 report |
| First year after 2018 ordinance | ~3 completed / 6 permits | 2019 |
| Average unit | ~570 sq ft · 1 bedroom · ~14.5 ft tall | 2022 report |
Salt Lake City's archived ADU annual reports run through 2022; more recent activity should be confirmed through current city permit data. Cost and fee figures are dated estimates that change over time — see our cost guide for current ranges.
The mix also shifted toward internal (basement) units after 2021, when a new state law made those a permitted use statewide. That policy shift is the backdrop for everything else on this page.
Want the version specific to you — not Salt Lake City?
A statewide or citywide number can't tell you whether your lot, zone, and budget support an ADU.
What changed in Utah ADU law (2019 → 2026)
Two state laws drive the trend. A 2021 law made internal ADUs a permitted use in residential zones statewide, and a 2026 law will require certain cities to allow detached ADUs on larger lots starting in October 2026. Neither erases local control over parking, size, utilities, or design — and that local control is exactly why the picture varies so much from city to city.
A few terms, defined once:
- Internal ADU
- a unit created within the existing footprint of a home (most often a basement apartment).
- Detached ADU
- a separate structure, like a backyard cottage or a unit over a detached garage.
- Owner occupancy
- a rule requiring the property owner to live on-site (in either the main home or the ADU).
- Setback
- the minimum distance a structure must sit from a property line.
- Impact fee
- a one-time fee some cities charge new construction to help pay for public infrastructure.
| Year | Law | What it did | Where it lives in code |
|---|---|---|---|
| 2019 | Moderate income housing law | Pushed Utah cities and counties to adopt housing strategies or risk losing certain state transportation funds; many chose to allow ADUs | Utah moderate income housing statutes |
| 2021 | House Bill 82 | Made internal ADUs a permitted use in residential zones statewide, effective Oct. 1, 2021; eliminated certain barriers (like requiring separate utilities) | Now codified at Utah Code §10-21-303 |
| 2026 | Senate Bill 284 | Requires specified municipalities to allow a detached ADU as a permitted use on qualifying lots of 11,000 sq ft or larger; takes effect Oct. 1, 2026 | Enacts Utah Code §10-21-304 |
On the 2021 internal-ADU law (HB 82): Utah's Office of the Property Rights Ombudsman explains that a qualifying internal ADU is a unit within an owner-occupied, detached single-family home, created within the home's existing footprint, and offered as a long-term rental of 30 or more consecutive days. Statewide, it's a permitted use in areas zoned primarily for residential use — but "statewide" doesn't mean "everywhere." Cities can still designate limited areas where new internal ADUs aren't allowed, require owner occupancy, impose design standards, require extra parking, require rental or ADU permits, restrict short-term rentals, and more. What the law eliminated is the blanket prohibition and certain outdated barriers.
On the 2026 detached-ADU law (SB 284): As of this page's July 2026 verification date, some Utah cities already allow detached ADUs under their own local rules — but the statewide requirement is not yet in effect. Utah Code §10-21-304 takes effect October 1, 2026, and will require specified municipalities to permit a detached ADU on larger lots (11,000 square feet and up), opening a path where many cities previously prohibited backyard units outright. "Specified municipality" is a defined term in Utah law — it doesn't mean every city. Local rules — setbacks, height limits, design standards, utility requirements, rental limits, owner occupancy — still apply. See the full detached ADU lot size requirements guide.
Why Utah ADU statistics are so hard to compare
Utah cities count ADUs differently, so you can't line up one city's number against another's and draw conclusions. The state's Moderate Income Housing reporting framework asks each city to report several ADU figures separately — and cities use different methods for each one.
In their annual housing reports, Utah municipalities are asked for things like:
the total known number of ADUs recorded as of the report date,
the number of building permits issued to construct an ADU in the reporting year, and
the number of business licenses or permits to rent an ADU issued in that year.
That's three different measures — and a fourth catch-all for "other permit types." One city might report mostly rental licenses; another mostly building permits; a third might only track internal ADUs it has formally registered. Stack those side by side and you're comparing apples to oranges.
| Source | What it reports | Verified figure | As of |
|---|---|---|---|
| Salt Lake City ADU Annual Report | Cumulative ADU building-permit applications, by status (2018–2022) | 170 applications — 44 completed, 36 under construction, 49 in review, 41 withdrawn | 2022 report |
| Bluffdale (Moderate Income Housing report) | Local ADU approvals over time | Most of the city's 20-year ADU total was approved after it adopted a friendlier detached-ADU ordinance in 2023 | 2023–24 report |
| Utah Housing Unit Inventory (state / UGRC) | Statewide parcel-level housing types | ADU category exists only for Salt Lake County; ADUs elsewhere are excluded | Jan. 2026 dataset |
What the reports do reliably show is direction, and the direction is up. More Utah cities are opting in. In Salt Lake County, 17 of 20 municipalities had already chosen ADUs as one of their moderate-housing strategies. By a 2018 county survey, nearly two-thirds of participating Utah cities said they already allowed ADUs in some form.
How Utah compares to national ADU trends
National ADU data is far richer than Utah's — but it's national, and it's heavily skewed by California. It's useful for scale and context, but you should never read a national or California number as if it were Utah's.
| Metric (national / other states) | Figure | Source & year |
|---|---|---|
| Estimated legal ADUs nationwide | ~1.4 million (about half in CA, FL, TX, GA) | Freddie Mac, 2020 |
| States with broad ADU laws | ~18 | Mercatus Center, 2025 |
| ADUs built in California in 2023 | ~23,000 (about double 2021) | John Burns Research & Consulting, 2025 |
| Share of California Enterprise-backed single-family purchase appraisals with an ADU | ~3% (3.0% in 2022; 2.9% in 2023) | Federal Housing Finance Agency |
| ADU permits filed nationwide (cumulative, over decades) | ~2.8 million | Shovels.ai, 2025 (proprietary permit dataset) |
Two things are worth pulling out of that table. First, notice how easy it is to mix up measures: Freddie Mac's ~1.4 million is an estimate of ADUs standing as of 2020, while the ~2.8 million permit figure is cumulative permits filed over decades — not units standing today. Those are different things, and conflating them is one of the most common ADU-statistics mistakes.
Second, even in California — the country's ADU leader — ADUs showed up in only about 3% of the single-family purchase appraisals FHFA analyzed. "ADU boom" still means a small slice of overall housing. Utah, which is earlier in its ADU curve, is smaller still.
What these statistics mean for your property
The useful takeaway isn't a statewide number — it's whether your specific city, lot, and budget support an ADU. Because Utah's rules and real-world feasibility vary so sharply from parcel to parcel, the only number that really matters for a decision is your own.
Before you spend money on design, it's worth screening these factors — the same ones that separate a smooth project from a stalled one:
- Jurisdiction and zoning — which city or county you're in, and your specific zoning district
- Lot size — including whether you clear thresholds like the 11,000 sq ft mark for the new detached-ADU rules
- Setbacks and lot coverage — many lots that look big enough fail once setbacks are applied
- Owner-occupancy rules — whether your city still requires you to live on-site
- Utilities — whether existing sewer, water, and electrical capacity can handle a second unit (a common, expensive surprise)
- Parking — what's required, and whether you lose covered parking in a garage conversion
- HOA or private covenants — these can restrict or prohibit detached structures even where the city allows them; internal ADUs have specific state-law protections when they comply with local ordinances and codes
- Rental plan — long-term rental, family housing, or short-term rental (which is more restricted) — see the rental income by city guide
More likely to be a fit when:
- ✓Your city has a clear ADU process
- ✓Your existing home supports the ADU type you want
- ✓Parking and utilities aren't major constraints
- ✓Your budget has room for surprises
More likely to be high-friction when:
- ✗City rules are unclear or in flux
- ✗The lot is tight or hard to meet setbacks on
- ✗Utilities are old or at capacity
- ✗An HOA restricts detached structures
- ✗The numbers only work if everything goes perfectly
If you're not sure which side of that line your property falls on, that's exactly what a feasibility review is for.
See what kind of ADU your property may support
Utah's rules vary by city, zone, and lot — get a property-specific read before spending money on plans.
How we track and verify Utah ADU data
We build these figures from official and primary sources, we label what each number measures, and we note when it was last checked. Where reliable data doesn't exist, we say so instead of filling the gap with an estimate.
Primary sources we use:
- Utah Code and the Utah Legislature (for state ADU law)
- The Utah Office of the Property Rights Ombudsman (for plain-language interpretation of state ADU rules)
- City and county Moderate Income Housing reports and ADU annual reports (for local counts)
- The Utah Geospatial Resource Center's Housing Unit Inventory (for the statewide housing dataset and its limits)
- City planning and zoning ordinances (for local rules)
- Reputable federal and research sources (for clearly-labeled national context)
How we classify a count — building permit, rental license, registration, completion, under construction, application, or "method unclear" — so a figure is never presented as more than it is. We exclude unverified third-party estimates, unpermitted-unit guesses, and vendor marketing claims.
How often we refresh: state law after each legislative session; city figures at least annually as new reports publish; national context annually. Because ADU laws and local reporting change often, treat the "last verified" date at the top as the anchor, and confirm anything time-sensitive for your own property.
Frequently asked questions
Request a Utah ADU feasibility review
The most useful statistic is whether your specific lot and city can support the ADU you want.
Sources
- 1.Utah Office of the Property Rights Ombudsman — Accessory Dwelling Units
- 2.Utah Legislature — Senate Bill 284 (2026), Local Land Use Modifications (enacts Utah Code §10-21-304)
- 3.Utah Code §10-21-303 (internal accessory dwelling units) and §10-21-304 (detached accessory dwelling units)
- 4.Salt Lake City Planning Division — 2022 ADUs Annual Report
- 5.Salt Lake City Planning Division — ADUs Annual Report page
- 6.Salt Lake City Planning Division — 2021 Utah Code Changes (internal ADU permitted use, effective Oct. 1, 2021)
- 7.Building Salt Lake — early Salt Lake City ADU permit figures
- 8.Salt Lake Tribune — "Mother-in-law apartments were seen as a way to boost SLC housing. Is it working?" (Feb. 14, 2022)
- 9.Utah Department of Workforce Services / Housing and Community Development — Moderate Income Housing reporting
- 10.Utah Geospatial Resource Center — Housing Unit Inventory
- 11.Bluffdale City — Moderate Income Housing Report (2023–24)
- 12.Draper City — Accessory Dwelling Units
- 13.Freddie Mac — "Identifying Accessory Dwelling Units from Real Estate Listing Data" (2020)
- 14.Federal Housing Finance Agency — "Trends in Median Appraised Value for Properties With Accessory Dwelling Units in California"
- 15.John Burns Research & Consulting — "ADU boom not helping housing crisis" (2025)
- 16.Mercatus Center — "A Taxonomy of State Accessory Dwelling Unit Laws 2025"
- 17.Shovels.ai — "America's ADU Boom: What 2.8 Million Permits Reveal" (2025, proprietary permit dataset)