Utah ADU Setback Requirements: How Far From the Property Line Can You Build?
Utah has no single statewide ADU setback. How far your accessory dwelling unit (ADU) must sit from the property line depends on your city, your ADU type, and your lot — not one state number. Inside-the-home units usually don't trigger a new setback; detached backyard units must meet local rules that often run about 3 to 10 feet from side and rear lines, though some cities require more. This page is most useful if you're weighing a detached unit or garage conversion — less so if you haven't picked a city yet. Every figure below needs local confirmation for your exact parcel.
An ADU (accessory dwelling unit) is a self-contained second home on the same lot as a primary house — a basement apartment, an attached addition, or a detached backyard cottage. A setback is the minimum required distance between a structure and a property line.
The quick answer
| Your question | Short answer | What to check next |
|---|---|---|
| Is there one Utah ADU setback? | No. State law lets each city set detached-ADU setbacks. | City, zoning district, ADU type, lot size. |
| Do internal/basement ADUs have setbacks? | Usually the bigger issues are building/fire code, egress, parking, licensing, and owner occupancy — not a new detached setback. | Whether the work changes the home's footprint. |
| How close can a detached ADU be? | It varies by city — for example, 3 ft in Salt Lake City, 5 ft in Millcreek, 10 ft (or a formula) in Provo. | Your city's row below + your property survey. |
| Can an existing garage keep its setback? | Sometimes, if you don't expand it and it meets building/fire code. | Whether the structure was legally built and whether you're adding on. |
| What else can kill the project? | Easements, lot coverage, height limits, parking, utilities, corner-lot rules, HOA covenants. | A full feasibility review. |
What are Utah ADU setback requirements?
Utah ADU setback requirements are set locally, not by one statewide number. State law defines ADU types and creates strong rules for internal ADUs (units created inside an existing home), but local governments still control most placement standards — including detached-ADU setbacks. So the right question isn't "What's the Utah setback?" It's "What setback applies to my city, my ADU type, my zoning district, and my lot?"
An ADU is not automatically a smart project just because Utah has become more ADU-friendly. The right project depends on your lot, city, utilities, budget, and use case. On a narrow or corner lot, setbacks can shrink a detached unit below a usable size — or leave no compliant footprint at all.
That's exactly why the smart first move is a feasibility screen, not a builder quote. If the unit can't legally fit, the quote won't mean much.
The four questions that decide your setback
- 1.Which city or county controls the property? Rules differ across the Wasatch Front and beyond.
- 2.What type of ADU is it? Internal, attached, detached, or a garage/accessory-building conversion.
- 3.Where are the real property lines and easements? Not the fence — the surveyed line.
- 4.How tall and how large is the ADU? Height and size can both change the required setback.
How far from the property line does a Utah detached ADU need to be?
A detached ADU — a standalone structure separate from the main house, like a backyard cottage or a garage with an apartment — is where setbacks matter most. The distance depends entirely on the local rule. Some cities use a fixed number, some tie it to the underlying zone, and some use a chart that scales with lot size and height.
A few real examples from official city sources:
- Salt Lake City: as little as 3 feet from side and rear property lines for a detached ADU (Salt Lake City ADU Handbook; City Code § 21A.40.200).
- Millcreek: at least 5 feet from a side or rear property line for a new detached ADU (Millcreek city ADU standards).
- Provo: 10 feet from any property line, or the primary home's existing setback from that same line, whichever is less (Provo City Code § 14.30.030).
Utah ADU setback requirements by city
The table below is a verified starting point from official city and county sources — not a permit approval. Cities use different structures, and several are actively updating their detached-ADU rules in 2026 (more on that later). Confirm the current rule for your parcel before you design.
All rows last checked July 2026.
| City / jurisdiction | Detached ADU setback snapshot | Other fit rules to check | Source |
|---|---|---|---|
| Salt Lake City | 3 ft side, 3 ft rear; corner side yard = 20% of lot width or 10 ft, whichever is less | Not allowed in the front yard; over 17 ft tall adds 1 ft of side/rear setback per foot of extra height (up to 24 ft pitched / 20 ft flat); detached unit capped at 1,000 sq ft | SLC City Code § 21A.40.200 |
| Millcreek | At least 5 ft from side or rear property line (new detached) | Must be in the rear yard; over 14 ft tall requires more than 5 ft; detached needs a lot ≥ 8,000 sq ft; up to 1,000 sq ft; garage conversions must replace covered parking; no separate utility meters; no ADUs on slopes > 30% | Millcreek ADU page |
| Provo | 10 ft from any property line, or the home's existing setback from that line, whichever is less | Must be in the rear/side yard; the accessory structure's footprint and height must be smaller than the main home; ≥ 200 sq ft; Provo notes 2026 state law may change its guidance | Provo City Code § 14.30.030 |
| Holladay | External ADUs use the same rear/side setbacks as accessory buildings, from a lot-size/footprint chart, plus a 25% setback increase per that chart | Eligibility tied to larger lots; height limited (about 25 ft); doors/access can't open into a required setback; landscaped buffer required | Holladay City ADU page |
| Draper | A detached ADU must meet the same building setbacks as a house in that zoning district | Currently allowed only on lots ≥ 12,000 sq ft (above the state's ~10,000 sq ft floor — confirm as the city aligns with the 2026 law); rear-yard structure; owner occupancy required; size capped; height limit; no separate meters | Draper City ADU page |
| Salt Lake County (unincorporated) | At least 10 ft from the rear property line and 6 ft from the main house; side yard setbacks depend on the zone and public utility easements | Not allowed in the front or corner-side yard unless the lot is ≥ 1 acre and the ADU is ≥ 30 ft from the front line; must sit ≥ 10 ft behind the home's front façade; detached needs a lot ≥ 7,000 sq ft (6,000 in the PC zone); height up to 20 ft or match the home | Salt Lake County ADU page |
| Murray | 10 ft rear, 10 ft side; corner-lot street side 20 ft | Not allowed in the front yard; Murray does not allow owner-built ADUs (a licensed contractor is required); no short-term rentals | Murray City ADU page |
| Ogden | Ogden's ADU code sets size and rear-yard-coverage limits and requires a site plan showing setbacks; the property-line setback follows the zone's accessory-structure standards (confirm for your zone) | Detached unit must be 300–800 sq ft and cover no more than 25% of the rear yard; height limited (about 25 ft); must keep a single-family appearance; a new entrance goes on the side or rear | Ogden City Code § 15-13-39 |
Cities are actively updating detached-ADU rules in 2026 — confirm the current requirement for your parcel before you design.
Do basement or internal ADUs have setback requirements?
A basement or internal ADU is usually different from a new detached unit, because it's created inside the home's existing footprint — so it typically doesn't add a new property-line setback. That does not mean it's automatically allowed. Under Utah Code § 10-21-303 (municipalities) and § 17-80-303 (counties), an internal ADU is a permitted use in residential zones but must still meet building, health, and fire codes, and cities may attach several conditions.
Cities commonly can require, for an internal ADU:
- A minimum lot size — cities may prohibit an internal ADU on a lot smaller than 6,000 square feet.
- One additional off-street parking space (with limited exceptions).
- Owner occupancy — a rule that the owner lives in either the primary home or the ADU.
- A rental permit or business license.
- A prohibition on short-term rentals (stays under 30 days, e.g., Airbnb).
When an internal ADU still hits a snag
Even inside the home, an internal ADU can run into a separate outside-entrance rule, a parking requirement, an owner-occupancy covenant, or an existing code violation. And if you expand the footprint to create the unit, you've turned it into a setback question after all.
Can an existing garage or accessory building keep its current setback?
Sometimes — and this is one of the most useful setback facts for Utah homeowners. Several cities let you convert a legally built, existing structure into an ADU while keeping its current setback, as long as you don't enlarge it and it meets current building and fire codes.
- Salt Lake City allows an existing accessory building converted to an ADU to keep its existing setbacks, but any expansion — including adding a second story — must meet the required setbacks (SLC ADU Handbook).
- Millcreek allows conversion of an existing detached structure "provided that the setbacks of the existing structure do not change" and the building meets code (Millcreek city ADU standards).
What Utah's 2026 detached ADU law changes — and what it does not
In 2026, Utah expanded its ADU law to cover detached ADUs, which used to be almost entirely a local decision. Under the change (Utah Code § 10-21-304), a "specified municipality" — broadly, larger cities, generally those of about 5,000 residents or more — must allow a detached ADU as a permitted use, meaning no special "conditional use" approval, on qualifying larger lots that contain a single-family dwelling. The enacting bill text puts that lot-size threshold at 10,000 square feet (some published summaries cite 11,000), and the law lets cities allow detached ADUs on smaller lots if they choose. Cities are bringing their codes into compliance through 2026.
What the 2026 law does not do for setbacks
The law does not erase local setbacks. It expressly lets cities keep requiring a detached ADU to conform to setback requirements based on proximity to property lines, and to regulate size, height, lot coverage, easements, window orientation, and building massing. A city can also decline a detached ADU where utility service or capacity isn't adequate.
Sources: Utah SB 284 (2026 General Session); Utah Code § 10-21-304; Utah Department of Commerce — ADUs and HOAs .
How to measure ADU setbacks on a Utah lot
Measure from the property line, not the fence. Fences, retaining walls, and landscaping are frequently a foot or more off the true boundary, and building to the wrong line is an expensive mistake. Cities require a site plan showing your property boundaries, existing structures, the proposed ADU, and the distances between them. The most reliable way to locate the actual lines is a licensed land surveyor.
Terms worth getting straight
- Rear yard, side yard, corner side yard, and front yard:
- Each often carries a different setback. Corner lots almost always have a larger "street-side" setback (20 feet in Murray, for example).
- Setback vs. easement:
- A setback is the required distance from a building to a property line. An easement is a strip of your land reserved for someone else's current or future use — most often a utility company. You generally can't build in an easement even if it sits inside the setback line, which means an easement can quietly shrink your buildable area more than the setback alone.
- Eaves, decks, balconies, and stairs:
- These can count. Salt Lake City, for instance, doesn't allow a balcony to extend into a required ADU setback.
Why setback is not the only fit test
A Utah ADU can meet the setback and still fail feasibility. It's better to learn that now than after you've paid for plans. The most common additional blockers:
- Easements — utility easements are not negotiable design preferences.
- Lot coverage — the share of your lot that buildings may cover; a detached unit plus your house and garage can exceed it.
- Height limits and privacy rules — taller units often trigger larger setbacks and window restrictions.
- Parking — most cities require at least one added off-street space, and converting a garage usually means replacing that covered parking.
- Utilities — water, sewer, and power capacity have to reach the unit; the 2026 law lets cities say no where capacity is inadequate.
- Short-term rental rules — meeting the setback does not make a nightly rental legal; many cities prohibit ADU short-term rentals outright.
- HOA covenants — a homeowners association can prohibit a detached ADU under its covenants even where the state and your city allow one (HOAs generally cannot ban internal ADUs). Check your CC&Rs early.
Setback feasibility checklist (before you pay for plans)
The goal here isn't to self-approve your ADU. It's to gather enough to avoid designing a unit that obviously conflicts with your property lines, easements, height, parking, or utilities.
- Property address and jurisdiction (city vs. unincorporated county)
- Lot size and zoning district
- ADU type: internal, attached, detached, garage conversion, or prefab/modular
- Existing home footprint
- Rough distance from the home to the rear and side property lines
- Where the fence sits versus the surveyed property line
- Any known utility easements
- Desired ADU footprint and height
- Details of any existing garage or accessory structure you'd convert
- Parking spaces available, and a plan to replace covered parking if converting a garage
- Intended use: family housing, long-term rental, home office, guest space
- Whether HOA covenants may apply
- Whether water, sewer, and power appear to reach the site
When a smaller, modular, or prefab ADU helps with setbacks — and when it doesn't
A smaller detached unit can make setbacks, lot coverage, and utility routing easier to satisfy, and a compact footprint may fit inside a tight buildable area where a larger design won't. But prefab or modular construction does not override city zoning, permits, foundation requirements, utility access, fire and building code, or easements. Compact design only helps after the site-fit question is answered — it can't make an illegal location legal.
For homeowners whose property looks like it can support a compact detached ADU, we may include practical build-path options, including compact or prefab partners, when they fit the site, budget, and local rules. That's a step that comes after feasibility, not before — and never a guarantee of approval, cost, or availability. Learn more about prefab ADU options in Utah.
Related Utah ADU guides
Utah ADU Laws (2026)
Full breakdown of state law, SB 284, and what cities can and can't require.
Utah ADU Parking Requirements
City-by-city table, state caps, and garage-conversion parking rules.
Utah ADU Owner Occupancy Requirements
Who must live on the property and how cities define it.
Detached ADU Builders Utah
Backyard cottage options, costs, and how to vet builders.
Prefab ADU Utah
Modular and prefab options, lead times, and site requirements.
Salt Lake County ADU Guide
Rules and lot requirements for unincorporated county residents.
Frequently asked questions
What we verified
We built this page from official and primary sources and checked the following before publishing:
Sources we checked
- Utah Property Rights Ombudsman — Accessory Dwelling Units (Utah Code §§ 10-21-303 / 17-80-303; § 11-36a-202 impact-fee exemption)
- Utah Department of Commerce — ADUs and HOAs (HOA authority over detached vs. internal ADUs)
- Utah Code § 10-21-304 — detached accessory dwelling units (enacted 2026)
- Salt Lake City — ADU Handbook · City Code § 21A.40.200
- Millcreek — Accessory Dwelling Units
- Provo — City Code § 14.30.030
- Holladay — housing / ADU information
- Draper — Accessory Dwelling Units Permits
- Salt Lake County — Office of Regional Development, ADUs
- Murray — ADUs
- Ogden — City Code § 15-13-39