How much are ADU permit fees in Utah?

There’s no single statewide number. Some cities charge a flat ADU application fee, but building permit and plan review fees are usually based on your project’s construction value, and detached units can add impact and utility fees. Interior conversions are generally the lowest-fee path.

Is there a statewide Utah ADU permit fee?

No. Utah law shapes internal-ADU rules and the impact-fee exemption, but each city publishes its own fee schedule and permitting process.

Do internal ADUs pay impact fees in Utah?

No. Utah Code § 11-36a-202 says constructing a qualifying internal ADU within an existing home is not subject to impact fees. You may still owe building permit, plan review, inspection, licensing, and code-compliance costs.

Are detached ADUs more expensive to permit?

Usually, yes. A detached unit is typically treated as new construction, so it can trigger impact fees, separate utility connections, and sometimes a conditional use permit — costs an interior conversion avoids.

Is the ADU fee the same as the building permit fee?

Usually not. The ADU fee is often a separate application or review charge. The building permit fee is calculated from your project’s value and covers inspections; plan review is frequently an added percentage of that permit fee.

Do I need a permit for a basement apartment in Utah?

Yes, if you’re doing construction, remodeling, adding safety upgrades, or renting the unit. The exact process depends on your city, but building-code compliance and a permit are the norm.

Does SB 284 change detached ADU rules?

Beginning October 1, 2026, SB 284 requires specified Utah cities to allow qualifying detached ADUs as a permitted use in certain residential zones, generally on lots 11,000 square feet or larger. Fees and other standards still come from your city, so verify locally.

Can I use another city’s fees to estimate mine?

Only as a rough gut check. Cities use different valuation tables, plan-review percentages, licensing rules, and impact-fee procedures, and water/sewer districts add their own charges.

What happens if my ADU was built without permits?

Don’t assume you can simply rent or sell it. Cities can require inspection, correction, and after-the-fact permitting, and unpermitted work can create insurance, financing, and resale problems.

Utah ADU Permit Fees by City: What You’ll Actually Pay in 2026

Q: Do standard or prefab ADU plans waive permit fees?

No. Salt Lake City states that its pre-approved standard plans still require a site review and all applicable review and permitting fees, and prefab units still need site-specific review, a permit, and inspections.

By Utah ADU Builders · Last verified: July 2026 · Sources: Utah Code §§ 10-21-303, 11-36a-202; city fee schedules; Utah Property Rights Ombudsman

A quick note on who we are: Utah ADU Builders is a Utah-focused ADU planning, feasibility, and builder-matching resource — not a city office, permit authority, law firm, lender, architect, engineer, or licensed contractor. We may earn compensation when homeowners request estimates or are connected with local professionals. That never changes how we explain Utah’s rules, fees, or permitting risks.

Utah has no single statewide ADU permit fee. What you pay is a stack — building permit, plan review, a 1% state surcharge, and often impact and utility connection fees — set by your city and your project’s value. The biggest swing is your ADU type: internal ADUs (built inside your home) are exempt from impact fees under Utah law; detached units are charged them and can add thousands to tens of thousands.

An ADU (accessory dwelling unit) is a second, smaller home on the same lot as a primary house — a basement apartment, a converted garage, or a backyard cottage. Utahns also call them mother-in-law apartments, granny flats, or casitas.

✓ What we verified for this page

Utah state law: the internal-ADU permitted-use rule (Utah Code § 10-21-303, formerly § 10-9a-530) and the impact-fee exemption for internal ADUs (Utah Code § 11-36a-202), plus the Utah Property Rights Ombudsman’s plain-language summary.
City fee methods: Salt Lake City, Provo, Cottonwood Heights, West Jordan, Lehi, North Salt Lake, and Ogden building/ADU pages and fee schedules.
Impact-fee sources: a Utah County city-by-city fee comparison and a special-service-district sewer impact fee (Timpanogos SSD, via Lehi).
2026 law change: Senate Bill 284, which expands detached-ADU access beginning October 1, 2026.
Cost inputs: every dollar figure is an estimate. Fee schedules change often — many Utah cities update them around July 1 — so confirm the current number for your address before you budget.

Diagram of Utah ADU permit fee components: application, building permit, plan review, state surcharge, impact fees, utility connection, rental license — Concept image; actual design, cost, and approval depend on site and local rules.

In This Guide

Permit Fees at a Glance
Why There’s No Flat Number
Fees by City
Internal vs. Detached: the Key Split
Do Internal ADUs Skip Impact Fees?
How Much Are Detached Impact Fees?
How to Estimate Your Costs
What Pushes Fees Higher
Can Prefab Plans Lower Fees?
Is It Cheaper to Skip Permits?
The Honest Bottom Line
FAQ
Sources

Utah ADU permit fees at a glance

Before anything else, here’s the honest shape of the answer. A city “ADU fee” is usually just one line on a longer bill. This is the full stack most Utah homeowners encounter, and which parts apply to each ADU type.

An impact fee is a one-time charge cities collect on new construction to help pay for the added demand a new home places on public systems — water, sewer, roads, and parks. It’s the line that most often surprises people, and it’s where internal and detached ADUs part ways.

Fee	What it is	Usually charged by	Internal ADU	Detached ADU
ADU application / review	The city's ADU-specific approval step	City planning	Often applies	Often applies (may include a conditional use permit)
Building permit	Permit to do the work, priced from project valuation	City building dept.	Applies	Applies
Plan review	Staff review of your plans before the permit issues	City building dept.	Applies	Applies
Trade permits	Electrical, plumbing, mechanical	City building dept.	Depends on scope	Usually applies
State surcharge	1% of the building permit fee, sent to the state	City (passed through)	Applies	Applies
Impact fees ⚠️	Capacity charge for roads, water, sewer, and parks	City and/or a special service district	Not charged for a qualifying internal ADU under Utah law	Usually charged — the biggest variable
Utility connection / meter	Hooking up or upgrading water, sewer, and power	City and/or utility district	Usually minimal	Can be significant
Rental / business license	Required by some cities if you'll rent the unit	City	If rented	If rented
Notice / deed-restriction recording	A city-required notice, deed restriction, or covenant, where required	County recorder	Where required	Where required

The takeaway: the application fee is rarely the number that matters. Plan review and — for detached units — impact and utility fees usually dwarf it.

See what kind of ADU your property may support

Check your likely fee path before you pay for plans or hire a builder.

Why “ADU permit fee” is never one flat number in Utah

There is no statewide ADU permit price because each Utah city sets its own fee schedule, and most building permit fees are calculated from your project’s valuation — not charged as a flat rate. Two identical basement apartments can cost different amounts to permit in Salt Lake City versus Provo, and a detached cottage almost always costs more to permit than an interior conversion.

Here’s the mechanic that trips people up: most Utah cities price the building permit from the estimated construction value of your project (often using the International Code Council’s construction-valuation tables). Salt Lake City bases building permit fees on total project valuation and charges a plan review fee equal to 65% of the building permit fee. Provo works the same way — permit fee from valuation, a 65% plan-check fee, and a 1% state fee on top. So the more your ADU costs to build, the more the permit costs. That’s why nobody — including us — can quote your exact permit fee without knowing your city, your ADU type, and your project’s value.

Utah ADU permit fees by city

Because cities price fees differently and update them often, the most useful comparison isn’t “which city is cheapest” — it’s how your city charges. The table below shows each city’s method and the ADU-specific quirks we verified. It is not a guaranteed total, and amounts change (many Utah cities update fee schedules around July 1), so confirm the current number for your address before you budget. All rows verified as of July 2026.

City / area	Building permit priced by	Plan review	ADU-specific notes	Impact fees	Source
Salt Lake City	Project valuation	65% of permit fee	Pre-approved standard ADU plans still need a site review and applicable fees; owner-occupancy required	Internal exempt; detached assessed	SLC Municipal Code § 18.20.020; SLC Building Services
Provo	Project valuation	65% of permit fee (+1% state fee)	ADU application fee; rental dwelling license if rented; recorded deed restriction; owner-occupancy required	Internal exempt; detached assessed	Provo City building FAQ; Provo City Code § 14.30.030
Cottonwood Heights	Project valuation	Per city schedule	Internal ADU = permitted use; detached ADU currently requires a conditional use permit (may change under SB 284 on 10/1/26); owner-occupancy required; no short-term rentals	Internal exempt; detached assessed	Cottonwood Heights ADU page
West Jordan	Project valuation (Utah State Construction Code)	Per city schedule	ADU application and owner affidavit required; conditional use process exists	Internal exempt; detached assessed	West Jordan development applications & fee schedule
Lehi	90% of ICC Building Valuation Data	Per city schedule	Regional sewer district charges its own impact fee (about $5,793/home, FY2026), separate from the city	Internal exempt; detached assessed	Lehi FY2026 fee schedule; Timpanogos SSD
North Salt Lake	Value of work (ICC valuation)	Per city schedule	Internal ADUs use a land-use permit the city lists as no-fee; a building permit is still required	Internal exempt; detached assessed	North Salt Lake ADU page & fee schedule
Ogden	Valuation-based (per Ogden fee schedule)	Per city schedule	Owner-occupied model (rent one unit, not both); a separate ADU review applies in addition to the building permit	Internal exempt; detached assessed	Ogden City fee schedule
St. George area (Washington County)	Project valuation (per jurisdiction)	Per jurisdiction	A regional water district (WCWCD) impact fee can be significant in the southwest	Internal exempt; detached assessed	Washington County / WCWCD fee schedules

How to read this. “Project valuation” means the city calculates your fee from what the work costs to build, so you need a rough project value or square footage to estimate it. “Internal exempt” reflects the statewide impact-fee rule. “Detached assessed” means the city — and often a separate water or sewer district — may charge impact and connection fees on a new detached unit; the amount varies by size, service demand, and district.

The same structure applies across Utah. Cities like Sandy, Draper, South Jordan, Murray, Millcreek, Orem, Layton, and Bountiful — and unincorporated Salt Lake County, served by the Greater Salt Lake Municipal Services District — price the building permit from project valuation, add plan review and a 1% state surcharge, exempt qualifying internal ADUs from impact fees, and assess detached units for impact and connection fees. What changes city to city is the exact plan-review percentage, the ADU application or license step, and — most of all — the local impact and utility-district fees.

Not sure which type fits your lot?

Check your ADU feasibility and fee path — before spending on design or permits.

Internal ADU vs. detached ADU: the single biggest factor in your fees

If you remember one thing, remember this: an internal ADU (a unit created inside your existing home’s footprint, like a basement apartment) is treated very differently from a detached ADU (a separate structure in the yard). The difference can be tens of thousands of dollars, mostly because of impact fees.

Comparison showing internal Utah ADUs exempt from impact fees, while detached ADUs may be assessed impact and utility fees depending on city, district, and project type — Concept image; actual design, cost, and approval depend on site and local rules.

Factor	Internal ADU	Detached ADU
What it is	A unit inside your existing home (e.g., a basement apartment)	A separate structure on your lot (e.g., a backyard cottage or garage apartment)
Statewide legal status	A permitted use in most residential zones for an owner-occupied home (Utah Code § 10-21-303)	Beginning Oct. 1, 2026, SB 284 requires specified cities to allow qualifying detached ADUs as a permitted use in certain residential zones (generally lots 11,000 sq ft or larger); standards and fees stay local
Impact fees	Not subject to impact fees (Utah Code § 11-36a-202)	A city — and often a utility or special district — can assess impact and connection fees
Typical extra approvals	Building permit, plan review, inspections	May require site/design review; a conditional use permit in some cities (limited for qualifying units under SB 284 starting 10/1/26)
Utilities	Often shares existing service; some cities limit you to 1–2 meters per utility	May need a separate connection and meter
Overall fee magnitude	Lower — mostly permit + plan review	Higher — permit + plan review + impact + connection fees

You can see this split at the city level. In Cottonwood Heights, an internal ADU is a permitted use on qualifying lots, while a detached ADU currently requires a conditional use permit — an extra approval step (and fee) that an interior conversion avoids. (SB 284 may narrow when a city can require that permit for a qualifying detached unit starting October 1, 2026, so confirm the current rule.)

Do internal ADUs really skip impact fees in Utah?

Yes — for a qualifying internal ADU built within your existing primary home, Utah law says the construction is not subject to impact fees (Utah Code § 11-36a-202). The Utah Property Rights Ombudsman states this plainly. It’s one of the strongest cost advantages in Utah’s ADU rules, and it can save several thousand dollars on a basement conversion.

But the exemption is narrower than many homeowners assume. It removes impact fees — not everything else. A “qualifying internal ADU” under state law is a unit created inside a detached, single-family home that is occupied as the owner’s primary residence, for a long-term rental of 30 days or more. Even then, your city can still require:

A building permit, plan review, and inspections
Trade permits (electrical, plumbing, mechanical)
An ADU application or approval step
A rental or business license if you rent the unit
Egress windows, fire separation, and other building/fire/health-code compliance
Owner-occupancy compliance. Utah’s internal-ADU protections apply to a home occupied as the owner’s primary residence, and cities can add their own owner-occupancy and rental conditions. This is city-specific, so verify yours.

And the exemption does not extend to detached units. A detached ADU is generally treated as new residential construction, so a city — and often a separate water or sewer district — can assess impact and connection fees.

How much are detached ADU impact fees in Utah?

For a detached ADU assessed as new construction, impact and connection fees are usually the largest and most city-specific part of your bill — commonly five figures. Generic national guides that quote “$1,000–$5,000 in permit fees” are describing the building permit alone and leaving out the fees that actually move your budget.

A real Utah anchor

A fee comparison compiled for Spanish Fork City using Utah Valley Home Builders Association data looked at the combined impact, building-permit, and hookup fees for a benchmark home — a quarter-acre lot with a $300,000 single-family valuation — across Utah County. The result ranged from roughly $12,200 in Lindon and $13,600 in Lehi up to about $29,500 in Highland.

Two honest caveats on that range: (1) It’s a benchmark for a full single-family home, not an ADU specifically. A smaller detached ADU may be assessed less, because some fees scale with size or valuation. But it shows the order of magnitude — far above the “$1,000–$5,000” figure floating around generic guides. (2) A city isn’t the only one charging you. In much of Utah, the water and sewer impact fees are set by a special service district, not the city itself. In Lehi, for instance, the regional sewer district’s single-family sewer impact fee was about $5,793 per home in its FY2026 schedule — a single line item, before water, transportation, parks, or the building permit. When you research “your city’s” fees, you often have to check the relevant water and sewer districts too.

This is exactly why a detached ADU deserves a feasibility check before you spend money on design: the fee stack alone can swing your budget by $15,000 or more depending on your city and lot.

How to estimate your ADU permit costs before you call a builder

You can get a realistic ballpark in six steps — no builder quote required. The goal isn’t a to-the-dollar figure; it’s knowing your fee categories and spotting the big variables before you spend on design.

Six-step checklist for estimating Utah ADU permit costs before requesting builder quotes — Concept image; actual design, cost, and approval depend on site and local rules.

1
Confirm your jurisdiction.
Your mailing city isn't always the city that issues your permit (unincorporated areas are often handled by a county or district). Pin down exactly who regulates your address.
2
Classify your ADU type.
Internal, garage conversion, attached addition, or detached. This decides your impact-fee exposure more than anything else.
3
Estimate your project value or square footage.
Most Utah cities price the building permit from valuation, so a rough construction budget gets you most of the way to the permit and plan-review fees.
4
Add plan review and trade permits.
In cities like Salt Lake City and Provo, plan review runs about 65% of the building permit fee, plus a ~1% state surcharge and separate electrical/plumbing/mechanical permits.
5
Flag impact and utility risk.
Internal ADU inside your home? Impact fees generally don't apply. Detached unit or new utility service? Budget for impact fees and connection/meter costs — and check the local water and sewer districts, not just the city.
6
Check rental licensing.
Planning to rent it? Some cities require a rental or business license and a recorded deed restriction, separate from your construction permit.

Skip the spreadsheet — check your ADU feasibility

Our tool checks your jurisdiction, ADU type, and likely fee categories so you know what you're dealing with before you pay for plans.

What can push your ADU fees higher than expected

Even a good estimate can be beaten by project-specific surprises. The most common ones in Utah:

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Utility upgrades. A new detached unit may need a separate water/sewer connection, a larger electrical service, or trenching. On older homes, a panel upgrade or new service is a real line item.
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Structural engineering. New construction and many garage conversions can require engineered, stamped plans — especially on sloped lots, older foundations, or homes with unusual layouts. Some cities let simple single-family or garage plans be drawn without a licensed professional if they're complete and legible, while larger or more complex projects trigger engineering.
▶
Fire, egress, and life-safety corrections. Basement ADUs often need code-compliant egress windows, ceiling height, and fire separation before they can be occupied.
▶
Resubmittals and design revisions. Every review cycle a city sends back can add time and professional cost, even when the city fees stay the same.
▶
Historic or overlay districts. Some neighborhoods carry extra design review that can add steps and requirements.
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Starting work before the permit issues. Cities can require after-the-fact permitting and charge penalty (sometimes doubled) fees for work done without a permit.

Do standard or prefab ADU plans lower your permit fees?

They can reduce design friction and speed up review, but they do not waive your city’s permit or review fees. Salt Lake City is explicit that using its pre-approved standard ADU plans still requires a site review and all applicable review and permitting fees.

Prefab and modular ADUs are the same story: even a factory-built unit still needs a foundation, utility connections, setback compliance (the minimum distance a structure must sit from your property lines), local zoning approval, a building permit, and inspections. The building method changes the construction timeline and sometimes the cost — not the requirement to permit it.

Disclosure: Utah ADU Builders partners with Nest Tiny Homes, a Utah prefab ADU company. If you’re matched with them or another professional, we may receive compensation. That relationship doesn’t change the fact above — a prefab or pre-approved plan still requires full city permitting and review fees. For a broader look at prefab options, see our prefab ADU Utah guide.

Is it cheaper to skip permits?

No — and it’s a common question worth answering directly. An unpermitted basement apartment can look cheaper up front, but it creates real risk later: failed inspections, safety hazards, problems getting insurance or financing, trouble legally renting it, and complications when you sell. If a buyer’s lender or appraiser flags unpermitted living space, you can end up paying for after-the-fact permitting and corrections anyway — often more than doing it right the first time. For most Utah homeowners, the permit fee isn’t just a city cost; it’s part of protecting the home’s rental and resale value.

The honest bottom line

An ADU is not automatically a smart project just because Utah has become more ADU-friendly. The right project depends on your lot, your city, your utilities, your budget, and how you’ll use the unit. For an interior conversion, the fees are usually modest and the impact-fee exemption works in your favor. For a detached unit, the fee stack alone can run well into five figures before you pour a foundation — and in some cities it’s the difference between a project that pencils out and one that doesn’t.

The most useful next step isn’t to call a builder for a quote you can’t yet evaluate. It’s to confirm two things first: what your property can actually support, and what your city (and its utility districts) will charge for it.

Request a Utah ADU Feasibility Review

Before you request quotes, confirm what your property can actually support and get a sense of your fee path — not just a generic range.

Utah ADU Builders may receive compensation when homeowners request estimates or are connected with local professionals. We are not a city permitting office and cannot guarantee approval, fees, financing, rental income, builder availability, or a property-value increase.

How we verify this information

We build each fact on official sources, in this order: Utah state code and the Utah Property Rights Ombudsman; city ADU pages and consolidated fee schedules; city building-department guidance; and county or special-service-district impact-fee schedules. We use homeowner forums only to understand common questions and concerns — never as proof for law, fees, or code.

What this page does not claim: it does not guarantee your final city invoice, permit approval, construction cost, rental legality, rental income, financing, utility approval, or HOA approval. Fee schedules change frequently, so treat every figure as a verified-as-of-July-2026 estimate and confirm current amounts for your specific address.

Frequently asked questions

Sources

Utah Code § 10-21-303 (internal accessory dwelling units, municipalities) and § 17-80-303 (counties) — renumbered from § 10-9a-530 and § 17-27a-526 (SB 1008, effective November 6, 2025)
Utah Code § 11-36a-202 (prohibitions on impact fees, including internal ADUs)
Utah Property Rights Ombudsman — accessory dwelling units
Utah Senate Bill 284 (2026), local land use / detached ADUs (effective October 1, 2026)
Salt Lake City Municipal Code § 18.20.020 (building permit and plan review fees); Salt Lake City Building Services (ADU standard plans)
Provo City building FAQ and Provo City Code § 14.30.030
Cottonwood Heights accessory dwelling unit requirements
West Jordan City development applications and fee schedule
Lehi City FY2026 fee schedule and connection/impact fees (incl. Timpanogos Special Service District sewer impact fee)
North Salt Lake fee schedule and accessory dwelling unit page
Ogden City fee schedule
Washington County and Washington County Water Conservancy District (WCWCD) fee schedules
Utah County fee comparison compiled for Spanish Fork City (Utah Valley Home Builders Association data)

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