Utah Tiny Home Zoning Laws
Utah has moved faster on ADU legislation than almost any state in this series, with three separate bills building on each other in just five years — and the most recent one has an active compliance deadline you should know about right now.
- SB284 (2026) expanded ADU rules to cover detached units for the first time, with an October 1, 2026 compliance deadline.
- The state floor only guarantees eligibility on lots of 11,000 sq ft or larger — a detail most guides miss.
- Applies to cities of the first through fourth class, plus fifth-class cities with 5,000+ residents.
- You're limited to one ADU per lot total, internal or detached, not both.
- Three bills in five years show this is actively evolving — verify current status before relying on older summaries.
A real, current deadline — with a lot-size catch: Senate Bill 284, passed in the 2026 session, expanded Utah's ADU rules to cover detached units (backyard cottages, garage apartments, standalone guest houses) for the first time — previously, many cities could prohibit these outright. It applies to cities of the first through fourth class, plus fifth-class cities with 5,000 or more residents; those without an existing detached-ADU policy must adopt one by October 1, 2026.7,8 The detail easy to miss: the statewide floor only guarantees eligibility on lots of 11,000 square feet or larger, codified at Utah Code § 10-21-304.8 A smaller lot may still qualify under a specific city's own, more generous ordinance, but isn't guaranteed to under the state floor alone. You're also limited to one ADU per lot total, internal or detached, not both.9
1. The Legislative Stack
| Law | What It Did |
|---|---|
| SB 174 (2021) | Requires most municipalities to allow at least one internal ADU by right in owner-occupied single-family homes4,7 |
| SB 44 (2024) | Additional ADU reforms building on SB 1744 |
| SB 284 (2026) | Expands the mandate to detached ADUs on qualifying lots of 11,000+ sq ft, for cities of 5,000+ residents; compliance deadline October 1, 20267,8 |
2. Salt Lake City: The Most Developed Program
Salt Lake City has had a formal ADU ordinance since 2018 and added five pre-approved standard plans in 2023 specifically to cut design costs for homeowners.4 This kind of pre-approved plan library is a genuine time and cost saver, since it skips a significant chunk of the custom design review process. Salt Lake County has separately authorized development of tiny house villages specifically to combat homelessness.2
3. Other Cities and Counties
| Location | Notable Detail |
|---|---|
| Utah County | Maximum ADU size 1,200 sq ft; 4 ft side/rear setbacks; two-story ADUs allowed; 6 ft building separation6 |
| Provo, Orem & the Wasatch Front | Catching up to Salt Lake City's program under state preemption from SB 174 and SB 2844 |
| Beaver County | No clearly defined countywide ADU ordinance; depends heavily on how the county classifies accessory structures in your specific area5 |
| Emery, Grand & parts of San Juan County | Rural counties with lenient enforcement on unincorporated parcels4 |
4. Homes on Wheels
THOWs are classified as recreational vehicles under Utah law and cannot serve as a primary residence on a standard residential lot.4 Full-time THOW living is restricted to licensed RV parks, manufactured home communities, and rural unincorporated land where local zoning permits long-term RV occupancy.4
5. State Code Baseline
Utah enforces a single statewide construction code, the Utah State Construction Code (IRC with Utah amendments), administered by the Division of Occupational and Professional Licensing.6 Zoning, however, remains entirely local across the state's 29 counties.6
How to Verify Your Specific Situation
- Confirm your target city's current compliance status with SB 284's October 1, 2026 deadline for detached ADU policies, and check whether your specific lot meets the 11,000 sq ft state-floor threshold or a smaller city-specific minimum.
- If in Salt Lake City, ask about the pre-approved standard plans, since they can meaningfully reduce design costs and review time.
- If considering a home on wheels, confirm your target location allows long-term RV occupancy rather than assuming general ADU flexibility extends to THOWs.
- In rural counties like Beaver, confirm accessory structure classification directly with the county rather than assuming a standard ADU pathway exists.
Research record: The 11,000 sq ft lot-size threshold and the one-ADU-per-lot limit were missing from earlier research on this page; we found and verified them against Utah Code § 10-21-304 as cited by a city-by-city SB 284 tracker, and against direct local news coverage of Utah County cities preparing for the October deadline. We have not compiled which specific Utah cities already had qualifying detached-ADU ordinances before SB 284 (and are therefore unaffected by the deadline) versus which still need to act; confirm your specific city's status directly. Information last checked August 2026.
Considering the ADU route? See how it compares nationally.
Read the National ADU Placement GuideSources
- Zook Cabins, "Tiny Home Regulations In Utah (2026 Guide)."
- Great Lakes Tiny Home, "What Counties in Utah Allow Tiny Houses."
- TinyHouse.com, "Tiny House Regulations in Utah (Complete Guide)."
- TinyHomeList, "Tiny Homes in Utah (UT)," updated April 2026.
- Zook Cabins, "ADU Regulations In Utah: The Complete Guide."
- Little Houses For Sale, "Tiny House Zoning in Utah."
- Cocoon, "Utah ADU Rules by City — 2026 SB284 Guide."
- Utah ADU Builders, "Utah ADU Rules by City: 2026 Data + Official Sources," citing Utah Code § 10-21-304; Daily Herald, "Utah County cities prepare for statewide detached ADU changes."
- Zander Real Estate Team, "Utah's New ADU Law: What It Actually Means," July 2026.
