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Accessory Dwelling Unit (ADU) in Lehi, Utah

Required for construction of a secondary dwelling unit on a residential property in Lehi, including internal (apartment) and detached ADUs. Planning application fee is $25 for both types; detached ADUs also trigger a $4,253 impact fee. Building permit fee is valuation-based per the standard schedule.

Verified 2026-06-30 · Source

When you need this permit

  • Property must qualify under Lehi City Development Code Title 11 — confirm zoning before applying
  • ADU planning application submitted to Lehi City Planning and Zoning
  • Building permit submitted to Building and Inspections after planning approval
  • Separate entrance from primary dwelling

Required documents

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Fee schedule

ADU Planning Application Fee — Internal (Apartment)Lehi City FY 2026 Fee Schedule (approved), Planning and Zoning section — Accessory Dwelling Units (Apartments) Application Fee
$25
ADU Planning Application Fee — DetachedLehi City FY 2026 Fee Schedule (approved), Planning and Zoning section — Accessory Dwelling Units - Detached Application Fee
$25
ADU Impact Fee — DetachedLehi City FY 2026 Fee Schedule (approved), Planning and Zoning section — Impact Fees for detached Accessory Dwelling Units
$4,253
Building Permit Fee (ADU construction)Lehi City FY 2026 Fee Schedule (approved) — ADU building permit uses standard valuation-based fee table. Plan review: 40% residential. State surcharge: 1%.
Valuation-based per Lehi City building permit fee schedule

Review timeline

Plan reviewTypical estimate — confirm current times with the Lehi building department
~14–30 business days

How long did your Accessory Dwelling Unit (ADU) permit actually take in Lehi?

Anonymous — one question, no email. Answers are combined and only shown once at least 5 people have reported.

Inspection process

  1. 1

    Foundation

    Footings, forms, rebar — before concrete pour

  2. 2

    Framing

    Structure, fire separation, egress windows

  3. 3

    MEP Rough-In

    Mechanical, electrical, plumbing rough-ins before walls closed

  4. 4

    Insulation

    Insulation and vapor barrier before drywall

  5. 5

    Final

    All work complete, smoke/CO detectors, address posted, ready for occupancy

See the full Lehi inspection guide — scheduling & re-inspection fees →

Tips

  • Utah HB 82 (2021) requires most cities to allow internal ADUs — confirm with Lehi Planning and Zoning whether your property qualifies and whether a detached ADU is allowed under your zone.
  • Detached ADUs trigger an impact fee of $4,253 in Lehi per the FY 2026 Fee Schedule.
  • The planning application fee ($25) is modest — the larger costs are the building permit (valuation-based) and the $4,253 impact fee for detached units.
  • Basement apartments require egress windows in each bedroom per the 2021 IRC.

Frequently asked questions

Lehi requires an accessory dwelling unit (adu) permit for: Property must qualify under Lehi City Development Code Title 11 — confirm zoning before applying; ADU planning application submitted to Lehi City Planning and Zoning; Building permit submitted to Building and Inspections after planning approval; Separate entrance from primary dwelling. If your project isn't listed, confirm with Lehi City Building and Inspections at (385) 201-1035 before starting work.

The ADU planning application fee is $25 (both internal and detached types per the FY 2026 Fee Schedule). Detached ADUs also have a $4,253 impact fee. The building permit fee is valuation-based per the standard Lehi fee schedule.

Plan review for an accessory dwelling unit (adu) permit in Lehi typically runs 14–30 business days. This is an estimate, not a published figure — confirm current review times with Lehi City Building and Inspections at (385) 201-1035.

You'll need: ADU Planning Application; Building Permit Application; Construction Plans; Site Plan. See the required-documents checklist on this page for details on each.

Lehi requires 5 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Framing, MEP Rough-In, Insulation, Final. Schedule each through Lehi City Building and Inspections ((385) 201-1035).

Apply through Lehi City Building and Inspections at 153 N 100 E, Lehi, UT 84043. Phone: (385) 201-1035, email: building@lehi-ut.gov. Office hours: Mon–Thu 8 a.m.–5 p.m. (office); phone hours Mon–Thu 7:30 a.m.–5 p.m., Fri 8 a.m.–3:30 p.m. — call (385) 201-1035 to confirm. Official information: https://www.lehi-ut.gov/departments/building-and-inspections/.

Lehi, Utah has adopted: 2024 International Building Code (IBC) — Utah Code § 15A-2-103(1)(a); effective 2026-07-01, superseded the 2021 edition. NOTE (verified 2026-07-16): Lehi's own Building and Inspections page still lists 'Current Codes: 2021 I Codes' — the city's page has not been updated to reflect the 2024 editions that took effect statewide on 2026-07-01.; 2021 International Residential Code (IRC) — Utah Code § 15A-2-103(1)(b); unchanged by the 7/1/2026 code cycle; 2024 International Plumbing Code (IPC) — Utah Code § 15A-2-103(1)(d); effective 2026-07-01, superseded the 2021 edition; 2024 International Mechanical Code (IMC) — Utah Code § 15A-2-103(1)(e); effective 2026-07-01, superseded the 2021 edition; 2024 International Fuel Gas Code (IFGC) — Utah Code § 15A-2-103(1)(f); effective 2026-07-01, superseded the 2021 edition; 2023 National Electrical Code (NEC) — Utah Code § 15A-2-103(1)(g); unchanged by the 7/1/2026 code cycle. NOTE (verified 2026-07-16): Lehi's own Building and Inspections page lists '2020 NEC' — this is stale independent of the 7/1/2026 code cycle; the 2023 NEC has governed statewide since its own adoption (predating this fix and not caused by it).; 2024 International Energy Conservation Code (IECC) — Utah Code § 15A-2-103(1)(h); effective 2026-07-01, superseded the 2021 edition; 2024 International Existing Building Code (IEBC) — Utah Code § 15A-2-103(1)(i); effective 2026-07-01, superseded the 2021 edition; 2024 International Swimming Pool and Spa Code (ISPSC), residential provisions — Utah Code § 15A-2-103(1)(n); effective 2026-07-01, superseded the 2021 edition; ICC/ANSI A117.1-2017 (Accessible and Usable Buildings and Facilities) — Lehi City Building and Inspections page; NOTE (verified 2026-07-16): The 2024 editions of IBC, IPC, IMC, IFGC, IECC, IEBC, and ISPSC took effect 2026-07-01 per Utah Code § 15A-2-103, superseding the 2021 editions that governed through 2026-06-30. The 2021 IRC and 2023 NEC were NOT changed by this cycle. Confirmed directly against the version of § 15A-2-103 effective 7/1/2026 (superseded 1/1/2027) at le.utah.gov. Lehi's own page (lehi-ut.gov/departments/building-and-inspections/) was checked live on 2026-07-16 and still reads 'Current Codes: 2021 I Codes' / '2020 NEC' — it reflects neither the 2024 code cycle nor the separately longer-standing 2023 NEC.. Local amendments apply — see the Lehi overview page for the full list.

Most likely yes. Utah state law (HB 82, 2021) requires cities to allow internal ADUs. Lehi may also allow detached ADUs depending on zoning. Contact Lehi Planning and Zoning to confirm. The ADU application fee is $25; detached ADUs also have a $4,253 impact fee per the FY 2026 Fee Schedule.

Sources & verification

Verified against official sources. Last reviewed 2026-06-30.

Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Lehi building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

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Accessory Dwelling Unit (ADU) in other cities

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