Utah ADU Builder
Utah ADU answers · updated 2026-10-17
Can you build an ADU on a quarter-acre lot in Utah?
A quarter acre is 10,890 sq ft: big enough that state law doesn't bar an internal ADU, but 110 sq ft short of S.B. 284's 11,000 sq ft detached floor. Which Utah cities allow a detached ADU on a quarter-acre lot.
Short answer
Usually yes for an internal ADU, and it depends on the city for a detached one. A quarter acre is 10,890 sq ft, which is above the 6,000 sq ft size at or below which Utah lets cities ban internal ADUs, but 110 sq ft under the 11,000 sq ft floor where S.B. 284 requires specified cities to permit a detached ADU.
Why the exact number matters
One acre is 43,560 sq ft, so a quarter acre is 10,890 sq ft. County records round acreage, usually to two decimals: a lot recorded as 0.25 acres can measure anywhere from about 10,672 to 11,108 sq ft. If your recorded plat or a survey shows 11,000 sq ft or more, the home is a single-family dwelling that is a permitted use there, and your city is a specified municipality, S.B. 284 requires the city to permit a detached ADU. The city can still limit its size, height, lot coverage and setbacks, require owner occupancy, allow only one ADU per lot, and refuse one where utilities lack capacity, and a development agreement it signed on or before May 6, 2026 can keep stricter rules (Utah Code 10-21-304).
Below 11,000 sq ft the state floor doesn't apply, so the city's own rule decides. The tables below come from the city research behind this site's map.
Cities whose own rule allows a detached ADU on a quarter-acre lot (39)
These cities set a detached-ADU lot minimum of 10,890 sq ft or less, or no separate minimum at all. Setbacks, lot coverage and size caps still decide whether a unit fits.
| City | Detached lot rule | S.B. 284 city | Checked |
|---|---|---|---|
| Park City | Lot of 3,750 sq ft or more | Yes | Verified 2026-09-24 |
| Kearns | Lot of 5,000 sq ft or more | Yes | Verified 2026-09-24 |
| Hyde Park | Lot of 6,000 sq ft or more | Yes | Verified 2026-09-24 |
| Layton | Lot of 6,000 sq ft or more | Yes | Verified 2026-10-17 |
| Payson | Lot of 6,000 sq ft or more | Yes | Researched 2026-09-07 |
| Santa Clara | Lot of 6,000 sq ft or more | Yes | Verified 2026-09-24 |
| South Salt Lake | Lot of 6,000 sq ft or more | Yes | Researched 2026-09-07 |
| Spanish Fork | Lot of 6,000 sq ft or more | Yes | Verified 2026-10-17 |
| Lindon | Lot of more than 6,000 sq ft | Yes | Researched 2026-09-07 |
| Midvale | Lot of more than 6,000 sq ft | Yes | Verified 2026-09-24 |
| South Jordan | Lot of more than 6,000 sq ft | Yes | Verified 2026-09-24 |
| Bountiful | Lot of 8,000 sq ft or more | Yes | Verified 2026-10-17 |
| Magna | Lot of 8,000 sq ft or more | Yes | Verified 2026-09-24 |
| Millcreek | Lot of 8,000 sq ft or more | Yes | Researched 2026-09-07 |
| Centerville | Lot of 8,500 sq ft or more | Yes | Verified 2026-10-17 |
| Tooele | Lot of 8,500 sq ft or more | Yes | Verified 2026-09-24 |
| Farmington | Lot of 10,000 sq ft or more | Yes | Researched 2026-09-07 |
| Herriman | Lot of 10,000 sq ft or more | Yes | Verified 2026-10-17 |
| Murray | Lot of 10,000 sq ft or more | Yes | Researched 2026-09-07 |
| Nibley | Lot of 10,000 sq ft or more | Yes | Verified 2026-09-24 |
| South Ogden | Lot of 10,000 sq ft or more | Yes | Researched 2026-09-07 |
| Syracuse | Lot of 10,000 sq ft or more | Yes | Researched 2026-09-07 |
| West Jordan | Lot of 10,000 sq ft or more | Yes | Verified 2026-09-24 |
| Brigham City | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Cedar City | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Clearfield | No separate ADU lot minimum | Yes | Researched 2026-09-07 |
| Cottonwood Heights | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Heber City | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Holladay | No separate ADU lot minimum | Yes | Verified 2026-10-17 |
| Hurricane | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Ivins | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| North Logan | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| North Salt Lake | No separate ADU lot minimum | Yes | Researched 2026-09-07 |
| Providence | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Riverton | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Salt Lake City | No separate ADU lot minimum | Yes | Researched 2026-09-07 |
| Smithfield | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| St. George | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
| Tremonton | No separate ADU lot minimum | Yes | Verified 2026-09-24 |
Cities that require more than a quarter acre (15)
A true quarter-acre lot falls short of these cities' detached minimums. If a plat or survey shows 11,000 sq ft or more, S.B. 284 can still apply in a specified municipality, even where the city's older figure is higher.
| City | Detached lot rule | S.B. 284 city | Checked |
|---|---|---|---|
| American Fork | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Bluffdale | Lot of 11,000 sq ft or more | Yes | Researched 2026-09-07 |
| Kaysville | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Lehi | Lot of 11,000 sq ft or more | Yes | Verified 2026-09-24 |
| Mapleton | Lot of 11,000 sq ft or more | Yes | Researched 2026-09-07 |
| North Ogden | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Orem | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Roy | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Sandy | Lot of 11,000 sq ft or more | Yes | Verified 2026-10-17 |
| Saratoga Springs | Lot of 11,000 sq ft or more | Yes | Verified 2026-09-24 |
| West Valley City | Lot of 11,000 sq ft or more | Yes | Researched 2026-09-07 |
| Draper | Lot of 12,000 sq ft or more | Yes | Verified 2026-10-17 |
| Grantsville | Lot of 12,000 sq ft or more | Yes | Researched 2026-09-07 |
| Vineyard | Lot of 12,000 sq ft or more | Yes | Researched 2026-09-07 |
| Salem | Lot of 43,560 sq ft or more | Yes | Researched 2026-09-07 |
Cities not listed
48 cities on file don't have a verified detached lot rule yet. Their city pages say so. The property map treats their lots under 11,000 sq ft as open rather than calling them, except in cities whose code doesn't generally allow detached ADUs (such as Alpine, Midway, Pleasant View, Taylorsville and Woods Cross), where it treats them as highly unlikely.
Sources
- Utah Code 10-21-303 (internal ADUs)
- Utah Code 10-21-304 (S.B. 284, detached ADUs)
- Utah Code 10-21-101 (definitions)
City rules come from this site’s dated research; each city page lists its official sources. This is planning information, not legal advice. How the property screen works.