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Residential Building Permit (Single-Family Dwelling / New Construction, Additions, ADUs) in Unincorporated Jefferson County, Idaho

Required for new single-family dwellings, additions, accessory dwelling units, remodels, and most accessory structures over 120 sq ft in unincorporated Jefferson County. Governed by the 2018 IRC as adopted by Ordinance 2022-02. Applications are submitted through the Jefferson County Planning, Zoning & Building Cityworks public portal; mechanical, electrical, and plumbing trade permits/inspections are handled separately by the Idaho Division of Occupational and Professional Licenses (DOPL), not the county.

Verified 2026-07-08 · Source

When you need this permit

  • Building permit required for new single-family dwellings, additions, ADUs, remodels, and accessory structures exceeding 120 sq ft in unincorporated Jefferson County
  • All construction must comply with the 2018 IRC
  • Register for and activate an account on the Jefferson County Cityworks public portal (Chrome or Firefox browser required) before applying
  • Submit Parcel Number, Parcel Size, County Zoning, Location Address/Subdivision info, flood zone status, full dimensional/square-footage data, and setback distances (N/E/W/S) as part of the online application
  • Site Plan showing all property lines, setbacks, easements, North arrow, existing/proposed structures with dimensions, driveway location, and canals/rivers/roads
  • Complete set of plans: floor plan(s) with room dimensions, footing/foundation details with steel requirements, truss layout, engineered truss design (stamped by an Idaho-licensed engineer), and all four building elevations
  • Recorded warranty deed demonstrating ownership or authorization to build
  • Idaho Contractor's License, or a completed Contractor Exemption form if owner-built Contractor
  • Access Permit from Jefferson County Public Works (county roads) or Idaho Transportation Department (state highways)
  • Septic Permit (approved) from Eastern Idaho Public Health, or an EIPH authorization-to-connect letter if tying into an existing/private sewer system
  • If in a mapped flood zone: Flood Plain Development Permit and Elevation Certificate
  • Mechanical (HVAC), electrical, and plumbing systems must be separately permitted and inspected by Idaho DOPL — not submitted as part of the county building permit package
  • All required attachments must be individually labeled PDF files uploaded through the portal

Required documents

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Fee schedule

Building permit fee — Total Valuation $1 to $500Jefferson County Fee Schedule 2026, Exhibit A (adopted 4-6-2026)
$26.46
Building permit fee — Total Valuation $501 to $2,000Jefferson County Fee Schedule 2026, Exhibit A
$26.46 for the first $500, plus $3.30 for each additional $100 or fraction thereof
Building permit fee — Total Valuation $2,001 to $40,000Jefferson County Fee Schedule 2026, Exhibit A
$75.96 for the first $2,000, plus $12.13 for each additional $1,000 or fraction thereof
Building permit fee — Total Valuation $40,000 to $100,000Jefferson County Fee Schedule 2026, Exhibit A
$536.90 for the first $40,000, plus $9.92 for each additional $1,000 or fraction thereof
Building permit fee — Total Valuation $100,001 to $500,000Jefferson County Fee Schedule 2026, Exhibit A
$1,132.10 for the first $100,000, plus $7.71 for each additional $1,000 or fraction thereof
Building permit fee — Total Valuation $500,001 to $1,000,000Jefferson County Fee Schedule 2026, Exhibit A
$4,216.10 for the first $500,000, plus $5.52 for each additional $1,000 or fraction thereof
Building permit fee — Total Valuation $1,000,001 to $5,000,000Jefferson County Fee Schedule 2026, Exhibit A
$6,976.10 for the first $1,000,000, plus $3.30 for each additional $1,000 or fraction thereof
Building permit fee — Total Valuation $5,000,001 and overJefferson County Fee Schedule 2026, Exhibit A
$20,176.10 for the first $5,000,000, plus $2.20 for each additional $1,000 or fraction thereof
Manufactured Home — Single WideJefferson County Fee Schedule 2026, Exhibit A
$250.00
Manufactured Home — Double WideJefferson County Fee Schedule 2026, Exhibit A
$500.00
Manufactured Home — Triple WideJefferson County Fee Schedule 2026, Exhibit A
$750.00
Plan Review FeeJefferson County Fee Schedule 2026, Exhibit A
15% of Building Permit Fee
GIS/Mapping Review FeeJefferson County Fee Schedule 2026, Exhibit A
$30.00 added to each application
Technology FeeJefferson County Fee Schedule 2026, Exhibit A
$30.00 added to each application
Inspection FeeJefferson County Fee Schedule 2026, Exhibit A
$90.00
Re-Inspection FeeJefferson County Fee Schedule 2026, Exhibit A
$90.00
Agricultural Exempt Building PermitJefferson County Fee Schedule 2026, Exhibit A
$250.00

Review timeline

Plan reviewUnincorporated Jefferson County’s published plan-review target
15–15 business days

How long did your Residential Building Permit (Single-Family Dwelling / New Construction, Additions, ADUs) permit actually take in Unincorporated Jefferson County?

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

Inspection process

  1. 1

    Layout Inspection

    Verifies structure layout on the site matches the approved site plan

  2. 2

    Footing Inspection

    Must occur before concrete is poured

  3. 3

    Foundation Inspection

    Must occur before concrete is poured

  4. 4

    Sheathing Inspection

    Building cannot be wrapped/house-wrapped before this inspection

  5. 5

    State Rough-In Inspections (Electrical, Plumbing, HVAC)

    Performed by Idaho DOPL, not the county — required before framing/insulation cover

  6. 6

    Framing Inspection

    After structural framing complete

  7. 7

    Insulation Inspection

    Before drywall/wall cover

  8. 8

    Drywall Inspection

    Seams cannot be taped or mudded before this inspection

  9. 9

    State Final Inspections

    Final electrical/plumbing/HVAC sign-off performed by Idaho DOPL

  10. 10

    Health Department Final

    If applicable — e.g., septic system final from Eastern Idaho Public Health

  11. 11

    Final Inspection by Building Department

    Final county sign-off; Certificate of Occupancy or Certificate of Completion issued after this inspection. Minimum 24 hours' notice required to schedule any inspection.

See the full Unincorporated Jefferson County inspection guide — scheduling & re-inspection fees →

Tips

  • Plan on a minimum of 15 business days for plan review after your application is submitted and confirmed complete — this is an official published figure from the county's own 'Building Permit Process: Plan Submittal to CO Issuance' document, not an estimate.
  • The county separately commits to notifying you within 10 business days whether your application package is complete (i.e., all required documents were included) — this is distinct from, and prior to, the 15-business-day plan review clock.
  • Electrical, plumbing, and HVAC/mechanical work is NOT permitted or inspected by Jefferson County — it goes through the Idaho Division of Occupational and Professional Licenses (DOPL) as a separate, parallel permit and inspection track. Budget for DOPL fees and scheduling in addition to the county's building permit.
  • You must register for and activate a Cityworks public portal account (Chrome or Firefox required) before you can submit any building permit application.
  • Minimum 24 hours' notice is required to schedule any county inspection.
  • Permits submitted before December 14, 2023 were not entered into the Cityworks system; call 208-745-9220 directly to schedule inspections on those legacy permits.
  • Accessory Dwelling Units are capped at 1,200 sq ft of living area (including any basement living space) and a maximum of 2 bedrooms.
  • One-story detached accessory structures (sheds, playhouses) under 120 sq ft do not require a building permit; fences up to 6 ft do not require a permit either.
  • The Plan Review Fee (15% of the building permit fee), GIS/Mapping Fee ($30), and Technology Fee ($30) must all be paid before departmental (zoning, floodplain, plan) review proceeds.

Frequently asked questions

Unincorporated Jefferson County requires a residential building permit (single-family dwelling / new construction, additions, adus) for: Building permit required for new single-family dwellings, additions, ADUs, remodels, and accessory structures exceeding 120 sq ft in unincorporated Jefferson County; All construction must comply with the 2018 IRC; Register for and activate an account on the Jefferson County Cityworks public portal (Chrome or Firefox browser required) before applying; Submit Parcel Number, Parcel Size, County Zoning, Location Address/Subdivision info, flood zone status, full dimensional/square-footage data, and setback distances (N/E/W/S) as part of the online application; Site Plan showing all property lines, setbacks, easements, North arrow, existing/proposed structures with dimensions, driveway location, and canals/rivers/roads; Complete set of plans: floor plan(s) with room dimensions, footing/foundation details with steel requirements, truss layout, engineered truss design (stamped by an Idaho-licensed engineer), and all four building elevations; Recorded warranty deed demonstrating ownership or authorization to build; Idaho Contractor's License, or a completed Contractor Exemption form if owner-built; Access Permit from Jefferson County Public Works (county roads) or Idaho Transportation Department (state highways); Septic Permit (approved) from Eastern Idaho Public Health, or an EIPH authorization-to-connect letter if tying into an existing/private sewer system; If in a mapped flood zone: Flood Plain Development Permit and Elevation Certificate; Mechanical (HVAC), electrical, and plumbing systems must be separately permitted and inspected by Idaho DOPL — not submitted as part of the county building permit package; All required attachments must be individually labeled PDF files uploaded through the portal. If your project isn't listed, confirm with Jefferson County Planning, Zoning & Building Department at 208-745-9220 before starting work.

Fees are valuation-based per the county's 2026 Fee Schedule (Exhibit A, adopted 4-6-2026), starting at $26.46 for projects valued $1-$500 and scaling up with additional per-$1,000 increments at each valuation tier (e.g., $536.90 for the first $40,000 plus $9.92 per additional $1,000 up to $100,000). A 15% Plan Review Fee, a $30 GIS/Mapping Fee, and a $30 Technology Fee are added to every application. Source: Jefferson County Fee Schedule 2026, Exhibit A.

The county's published process document states plan review takes approximately 15 business days for a non-commercial (residential) building permit application, after your application has been confirmed complete and required fees paid. Separately, the county aims to notify you within 10 business days whether your submitted application package is complete. Source: Jefferson County 'Building Permit Process: Plan Submittal to CO Issuance' (Date of Form: June 26, 2025) and the ADU Help Guide (Date of Form: June 26, 2025).

You'll need: Single Family Dwelling Help Information (Date of Form: January 2, 2024); Site Plan; Complete Set of Plans (Floor Plan, Truss Layout, Engineered Truss Design, Elevations); Recorded Warranty Deed; Idaho Contractor's License or Contractor Exemption Form; Access Permit; Septic Permit (or EIPH Authorization to Connect). Depending on your project, Unincorporated Jefferson County may also ask for: Accessory Dwelling Unit (ADU) Building Permit Application – Help Guide (Date of Form: June 26, 2025); Flood Plain Development Permit and Elevation Certificate. See the required-documents checklist on this page for details on each.

Unincorporated Jefferson County requires 11 inspection(s) for a residential building permit (single-family dwelling / new construction, additions, adus), in order: Layout Inspection, Footing Inspection, Foundation Inspection, Sheathing Inspection, State Rough-In Inspections (Electrical, Plumbing, HVAC), Framing Inspection, Insulation Inspection, Drywall Inspection, State Final Inspections, Health Department Final, Final Inspection by Building Department. Schedule each through Jefferson County Planning, Zoning & Building Department (208-745-9220).

Apply through Jefferson County Planning, Zoning & Building Department at 210 Courthouse Way, Suite 170, Rigby, ID 83442. Phone: 208-745-9220. Office hours: Mon–Fri 9:00 AM – 5:00 PM. Official information: https://www.jcgov.us/231/Planning-Zoning-Building.

Unincorporated Jefferson County, Idaho has adopted: 2018 International Building Code (IBC) — adopted by Jefferson County Ordinance 2022-02, effective March 7, 2022; 2018 International Residential Code (IRC) — adopted by Jefferson County Ordinance 2022-02, effective March 7, 2022. Local amendments apply — see the Unincorporated Jefferson County overview page for the full list.

No. Jefferson County's own Single Family Dwelling and ADU help documents both state that mechanical, electrical, and plumbing systems must be permitted and inspected by the Idaho Division of Occupational and Professional Licenses (DOPL), not the county Building Department. These are separate permits obtained directly from DOPL. Source: Jefferson County Single Family Dwelling Help Information and Accessory Dwelling Unit Help Guide.

Sources & verification

Verified against official sources. Last reviewed 2026-07-08.

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 Unincorporated Jefferson County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

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