Before you build

Use this checklist after you evaluate a property. Statewide “likely” means the property clears the public statutes we can see — not that you have a permit. Work through these items with your city before you hire a designer or pour a foundation.

1.Owner occupancy

Utah’s statewide ADU rules generally expect the owner to live in the primary home or the ADU. Confirm how your city documents occupancy.

2.Zoning district (not assessor class)

County assessor labels are not city zoning. Ask planning which zone your parcel is in and whether ADUs are allowed there today.

3.Property size and setbacks

Cities may prohibit internal ADUs on properties of 6,000 sq ft or less. Detached units under S.B. 284 need 11,000+ sq ft for the statewide mandate — local setbacks, height, and lot coverage still apply.

4.Parking

Expect at least one additional space for many internal ADUs. Detached ADU parking is capped by state law in specified municipalities, but local design still matters.

5.Utilities and building codes

Sewer, water, electrical capacity, fire access, and egress can stop a project that looks fine on paper. Talk to building and utility staff early.

6.HOA / planned development

State law limits HOA bans on internal ADUs; detached units can still be restricted by covenants. Read your CC&Rs before you design a backyard unit.

7.Rental duration

Internal ADUs are meant for stays of 30+ consecutive days. Cities may require 90+ days for detached ADUs under S.B. 284. Short-term rental rules are separate.

8.Timeline for detached ADUs

The statewide detached-ADU mandate is operative October 1, 2026. Before then, local ordinance controls whether a backyard unit is allowed.

9.Bring a property packet to planning

Print or share your Utah ADU Builder summary (address, parcel ID, property size, both verdicts) and ask the counter to confirm zoning and next permit steps in writing.

City ADU guides

Browse internal vs detached ADU guidance for Wasatch Front cities and Utah cities over 25,000 residents — organized by county.

Open the Utah city ADU database

Want the legal summary behind the map colors? See How it works.