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Accessory Dwelling Unit (ADU) Permit in Nampa, Idaho

Required for construction of a new accessory dwelling unit on a residential property in Nampa. Nampa provides a dedicated ADU Building Permit Application & Checklist.

Verified 2026-06-29 · Source

When you need this permit

  • Verify ADU is permitted in the property's zoning district with Planning & Zoning
  • Submit Residential ADU Building Application & Checklist
  • Plans must comply with 2018 IRC
  • Trade sub-permits (electrical, plumbing, mechanical) required separately

Required documents

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Fee schedule

ADU Building Permit — valuation-based per Exhibit ANampa Exhibit A Schedule of Permit Fees (Dec 2021)
Per Nampa Exhibit A valuation table; plan review is 65% of permit fee
Reinspection (after first reinspection for same item)
$55.00 flat fee

Review timeline

Plan reviewNampa’s published plan-review target
15–15 business days

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

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

Inspection process

  1. 1

    Foundation / Footings

    Before concrete pour — verify depth (24-inch frost line for full foundations), forms, rebar

  2. 2

    Framing

    Structural framing, egress windows, fire separation before walls covered

  3. 3

    MEP Rough-In

    Mechanical, electrical, and plumbing rough-ins under separate trade permits

  4. 4

    Final

    All work complete, smoke/CO detectors, address posted; Certificate of Occupancy issued

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

Tips

  • Nampa's plan review target for ADUs is 15 working days per the published Plan Review Processing Time Frames (Aug 2024) — same as new residential.
  • Confirm ADU zoning eligibility with Planning & Zoning at (208) 468-4430 before spending resources on design.
  • Trade sub-permits (electrical, plumbing, mechanical) are required separately for ADU construction.

Frequently asked questions

Nampa requires an accessory dwelling unit (adu) permit for: Verify ADU is permitted in the property's zoning district with Planning & Zoning; Submit Residential ADU Building Application & Checklist; Plans must comply with 2018 IRC; Trade sub-permits (electrical, plumbing, mechanical) required separately. If your project isn't listed, confirm with Nampa Building Safety & Code Department at (208) 468-5435 before starting work.

In Nampa, the published ADU Building Permit — valuation-based per Exhibit A is: Per Nampa Exhibit A valuation table; plan review is 65% of permit fee. Additional published fees: Reinspection (after first reinspection for same item) — $55.00 flat fee. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Nampa's published plan-review target for an accessory dwelling unit (adu) permit is 15–15 business days.

You'll need: Residential ADU Building Application & Checklist (Oct 2024); Construction Drawings; Energy Code Compliance Documentation. See the required-documents checklist on this page for details on each.

Nampa requires 4 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation / Footings, Framing, MEP Rough-In, Final. Schedule each through Nampa Building Safety & Code Department ((208) 468-5435).

Apply through Nampa Building Safety & Code Department at 500 12th Ave South, Nampa, ID 83651. Phone: (208) 468-5435, email: buildinginspections@cityofnampa.us. Office hours: Mon–Fri 8:00 AM – 5:00 PM. Official information: https://www.cityofnampa.us/163/Building-Safety-Code.

Nampa, Idaho has adopted: 2018 International Residential Code (IRC); 2018 International Building Code (IBC); 2018 International Existing Building Code (IEBC); 2018 International Fire Code (IFC); 2018 International Energy Conservation Code (IECC) — Residential and Commercial; 2018 International Mechanical Code (IMC); 2018 International Fuel Gas Code (IFGC); 2017 Idaho State Plumbing Code; 2023 National Electrical Code (NEC); 2009 ICC/ANSI/A117.1 (Accessibility); 2015 NFPA A30 Code for Motor Fuel Dispensing Facilities and Repair Garages; 2015 NFPA 99 Health Care Facilities Code. Local amendments apply — see the Nampa overview page for the full list.

ADUs are allowed on qualifying residential properties in Nampa. You must first confirm your zoning district allows an ADU with Planning & Zoning at (208) 468-4430, then apply using the Residential ADU Building Application & Checklist through the CSS online portal.

Sources & verification

Verified against official sources. Last reviewed 2026-06-29.

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 Nampa 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) Permit in other cities

Boise, IdahoIdaho Falls, IdahoMeridian, IdahoAlbuquerque, New MexicoArvada, ColoradoAurora, ColoradoBoulder, ColoradoBountiful, Utah

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