Utah · S.B. 284 · in effect October 1, 2026
Which lots Utah’s detached-ADU law reaches.
Larger Utah cities must now allow a detached ADU on a lot of 11,000 sq ft or more that has a single-family home. In the 11 covered cities whose zoning maps and county records we could read, 30,265 lots of that size have a home on record. Which of them are single-family in a zone that permits it is for each City to confirm.
The law, verbatim
Three tests, one of them the City’s.
“A specified municipality shall adopt a land use regulation that permits a detached accessory dwelling unit on any lot or parcel that is 11,000 square feet or larger and contains a single-family dwelling, if the single-family dwelling is a permitted use on the lot or parcel.”Utah Code 10-21-304(1)(a), enacted by S.B. 284 (2026), effective October 1, 2026
“Specified municipality” (10-21-102(25)): a first- to fourth-class city, or a fifth-class city of 5,000 or more in a first-, second- or third-class county. Towns are not included.
City by city
Lots that pass the size and dwelling tests.
Residential parcels of at least 11,000 sq ft with a home on the county record, inside the City’s own zoning map. Where the county’s unit counts are reliable, only single-unit lots are counted. Counts, not determinations.
| City | Law applies? | Lots ≥ 11,000 sq ft with a home | Largest zoning districts among them | Parcels as of |
|---|---|---|---|---|
| South Jordan Salt Lake County · pop. 80,331 | Applies A city of 80,331 (first- to fourth-class). | 8,782 Exactly one housing unit on the county record. | R-2.5 (4,527) · R-1.8 (2,907) · R-3 (855) · P-C (208) | Mar 26, 2026 |
| Washington Washington County · pop. 30,686 | Applies A city of 30,686 (first- to fourth-class). | 4,435 Exactly one housing unit on the county record. | PUD-R (750) · R-1-10 (625) · R-1-12 (603) · R-1-15 (569) | Oct 23, 2025 |
| Plain City Weber County · pop. 8,101 | Applies — confirm county class A fifth-class city of 8,101 in a county we infer to be class 2. | 2,543 A home on record; this county’s unit counts cannot tell single-family from a duplex. | RE-20 (1,122) · RE-15 (968) · R-1-11 (332) · A-2 (56) | Oct 29, 2025 |
| Saratoga Springs Utah County · pop. 44,070 | Applies A city of 44,070 (first- to fourth-class). | 2,431 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R1-10 (2,111) · PC (286) · R3-6 (17) · R1-9 (13) | Oct 30, 2025 |
| Heber Wasatch County · pop. 17,438 | Applies A city of 17,438 (first- to fourth-class). | 2,283 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-1 (1,007) · PC (474) · R-2 (387) · R-3 (307) | Oct 31, 2024 |
| Farr West Weber County · pop. 7,881 | Applies — confirm county class A fifth-class city of 7,881 in a county we infer to be class 2. | 2,054 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-1-15 (1,313) · A-1-R (337) · A-1 (327) · R-1-10 (61) | Oct 29, 2025 |
| Taylorsville Salt Lake County · pop. 59,010 | Applies A city of 59,010 (first- to fourth-class). | 2,046 Exactly one housing unit on the county record. | R-1-8 (733) · R-1-10 (704) · R-1-20 (299) · R-1-7 (74) | Mar 26, 2026 |
| Eagle Mountain Utah County · pop. 49,514 | Applies A city of 49,514 (first- to fourth-class). | 2,039 A home on record; this county’s unit counts cannot tell single-family from a duplex. | Residential (660) · Medium Density (288) · Town Core Residential (272) · Residential - Tier I (180) | Oct 30, 2025 |
| South Weber Davis County · pop. 8,037 | Applies — confirm county class A fifth-class city of 8,037 in a county we infer to be class 2. | 1,681 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-M (1,147) · R-L (350) · A (114) · R-LM (49) | Nov 26, 2025 |
| North Logan Cache County · pop. 11,228 | Applies A city of 11,228 (first- to fourth-class). | 1,654 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-1-12 (854) · RE-1 (485) · R-1-10 (185) · R-1-15 (45) | Oct 23, 2025 |
| Roosevelt Duchesne County · pop. 6,960 | Likely not covered Fifth-class city in a county we infer to be class 4. | 895 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-1-10 (321) · R-1-6 (214) · R-R-1 (125) · R-M-18 (88) | Oct 23, 2025 |
| Lake Point Tooele County | Likely not covered Population not on record here; small towns are outside the definition. | 732 A home on record; this county’s unit counts cannot tell single-family from a duplex. | RR-1 (731) · CH (1) | Oct 23, 2025 |
| La Verkin Washington County | Likely not covered Population not on record here; small towns are outside the definition. | 503 Exactly one housing unit on the county record. | R-1-14 (191) · R-1-8 (178) · R-1-10 (115) · COMM (6) | Oct 23, 2025 |
| Uintah Weber County | Likely not covered Population not on record here; small towns are outside the definition. | 379 A home on record; this county’s unit counts cannot tell single-family from a duplex. | RE-20 (312) · RE-20 RR (63) · AG (2) · C1 (1) | Oct 29, 2025 |
| Ballard Uintah County | Likely not covered Population not on record here; small towns are outside the definition. | 337 A home on record; this county’s unit counts cannot tell single-family from a duplex. | RA1 (168) · A1 (101) · R2 (53) · C1 (12) | Oct 23, 2025 |
| Washington Terrace Weber County · pop. 9,196 | Applies — confirm county class A fifth-class city of 9,196 in a county we infer to be class 2. | 317 A home on record; this county’s unit counts cannot tell single-family from a duplex. | R-1-10 (171) · R-1-6 (111) · R-1-8 (23) · IDZ (5) | Oct 29, 2025 |
| Vernon Tooele County | Likely not covered Population not on record here; small towns are outside the definition. | 288 A home on record; this county’s unit counts cannot tell single-family from a duplex. | 5 ac lots (141) · RR-1 (49) · 40 ac lots (30) · A-20 (27) | Oct 23, 2025 |
| Ephraim Sanpete County · pop. 5,805 | Likely not covered Fifth-class city in a county we infer to be class 4. | Not screened 55% of the county’s parcels here have no lot size or property class on record. | RA (129) · R1 (33) · R2 (9) · R4 (2) | Oct 23, 2025 |
| Kearns Salt Lake County | Ask counsel Kearns is a metro township, not a city; whether it is a “specified municipality” needs counsel. | 162 Exactly one housing unit on the county record. | R-1-8 (63) · R-1-6 (61) · R-1-7 (37) · RMH (1) | Mar 26, 2026 |
| Farmington Davis County · pop. 24,934 | Applies A city of 24,934 (first- to fourth-class). | Not screened 100% of the county’s parcels here have no lot size or property class on record. | — | — |
| Monticello San Juan County | Likely not covered Population not on record here; small towns are outside the definition. | Not screened 22% of the county’s parcels here have no lot size or property class on record. | — | — |
| Woods Cross Davis County · pop. 11,490 | Applies A city of 11,490 (first- to fourth-class). | Not screened 100% of the county’s parcels here have no lot size or property class on record. | — | — |
County classes are inferred from 2020 Census population under Utah Code 17-50-501, not taken from the Lieutenant Governor’s classification; “confirm county class” means exactly that.
What the count does not settle
Six things a City checks before telling a resident yes.
- Whether single-family is a permitted use in each district. The third test needs the City’s code; the districts are listed so staff can check them in one pass.
- Development agreements. The statute does not override ADU limits in a development agreement signed on or before May 6, 2026 (10-21-304(5)(b)). Master-planned communities are the obvious place to look.
- Utility access and capacity. A City may refuse a detached ADU without adequate sewer, water, power or storm-water access, or system capacity (4)(f). We do not read capacity.
- Where on the lot it can go. Setbacks, size, height, coverage, easements and front yards remain the City’s rules (4)(a)–(b).
- Occupancy and rental rules. A City may require the owner to live on the lot and bar rentals under 90 days (4)(b)–(c).
- The county record itself. Acreage and unit counts are the assessor’s. Condominiums and lots with more than one unit are left out.
Check one lot.
Type an address. You get its zoning district, lot size and constraints, with the source on each line.
For City staff
Get your city’s lot list.
Parcel ID, address, lot size, housing units, year built and zoning district for every lot that passes the first two tests — as a spreadsheet, for your staff, not published. Tell us your city.
Sources: Utah Geospatial Resource Center parcel records (LIR) and each City’s published zoning map, read on Oct 1, 2026. Buildability for cities · South Jordan proposal