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Residential Building Permit (New Construction / Addition / Accessory Structure) — Unincorporated Madison County, Idaho · Requirements sheet
Verified 2026-07-13 · Source: https://www.madisoncountyid.gov/departments/building_department/building_permit/index.php
PermitBase is an independent reference and is not affiliated with any government agency. Requirements change and vary by project — confirm current details with the building department before you submit.
Residential Building Permit (New Construction / Addition / Accessory Structure) in Unincorporated Madison County, Idaho
Required for detached one- and two-family dwellings and associated accessory structures in unincorporated Madison County — new construction, additions, basement finishes, remodels, garages, shops, decks, barns, and carports. Madison County Building Department has issued permits since 1976. Governed by the 2018 IRC as adopted and locally amended by Madison County Code Chapter 103. Each structure on a property requires a separate permit unless otherwise approved by the Building Official. Applications may be submitted via the county's iworq online Building Permit Portal or by physical/PDF submission.
Verified 2026-07-13 · Source
When you need this permit
- Building permit required for all new residential construction, additions, basement finishes, remodels, and accessory structures in unincorporated Madison County
- Septic Permit from Eastern Idaho Public Health required prior to Building Permit approval for new dwellings, or for remodels adding a bedroom/bathroom, or connecting to an existing septic system
- Recorded Warranty Deed (obtainable from the Madison County Clerk's Office); if applicant is not the legal owner, a notarized Affidavit of Legal Interest is required
- Site Plan showing setbacks, well, septic, property lines, and driveway(s)
- Copy of the Building Contractor's State of Idaho Registration, unless the project is owner-built
- One electronic copy (PDF) and/or one physical copy of plans, drawn to scale (minimum 1/8" = 1'-0"), formatted on 11"x17" paper, including: cross sections, elevations, full foundation drawing, window & door schedule, engineered truss design, engineered floor layout design
- Open spaces exceeding 900 sq ft require engineered plans per IRC Table R602.10.1.3 (seismic bracing), as determined by the Building Official
- Preliminary Elevation Certificate required before permit issuance if property is in a designated floodplain; Final Elevation Certificate required before Certificate of Occupancy
- Driveway Access Permit from the Madison County Road & Bridge Office
- Copy of subdivision covenants, if applicable
- Energy code compliance via prescriptive method (Prescriptive Path form in application) or REScheck analysis (Climate Zone 6B)
- Non-refundable Permit Fee Deposit due at submittal: $100 for accessory structures, $500 for non-accessory structures (including dwellings) — applied toward the total permit fee if approved
- Additional approvals may be required: Administrative Permit/ADU approval from Planning & Zoning (for more than one dwelling unit on a parcel), Fire Marshal review for properties with significant slopes, Army Corps of Engineers permits for wetlands, Road & Bridge/Corps approval for bridges
- Electrical and plumbing work requires a SEPARATE permit through the City of Rexburg Building Department (contracted electrical inspection authority per I.C. 54-1001) — NOT issued by Madison County
Required documents
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Fee schedule
Non-refundable Permit Fee Deposit (due at submittal, applied toward total fee)Building Permit Application (Fillable v2, 2026-01-22), Checklist item 10
$500 for dwellings/non-accessory structures; $100 for accessory structures
Total estimated permit fee (Permit + 10% Plan Review), by square footageMadison County Building Department Permit Fee Estimates (Building), effective January 2025 — estimates only, subject to change; calculated using ICC Building Valuation Data with a fixed 10% plan review; final fee determined by county staff at permit issuance
0–1,500 sq ft: $1,450 | 1,501–2,500 sq ft: $2,175 | 2,501–3,500 sq ft: $2,900 | 3,501–4,500 sq ft: $3,625 | 4,501–5,500 sq ft: $4,300 | 5,501–6,500 sq ft: $4,825
Review timeline
Plan reviewUnincorporated Madison County’s published plan-review target
10–10 business days
Inspection process
- 1
Footing/Foundation
Site plan and foundation verified per approved plans before concealment
- 2
Framing
After framing, sheathing, and rough-in trades complete, before insulation or wall cover
- 3
Final
All work complete per approved plans; permit number and site address must be posted and visible from the roadway prior to inspection or the inspection fails/is not carried out
See the full Unincorporated Madison County inspection guide — scheduling & re-inspection fees →
Tips
- Electrical and plumbing permits are NOT issued by Madison County — they are handled by the City of Rexburg Building Department under a county-city inspection contract (Idaho Code 54-1001). Apply via https://apply.rexburg.org/publicapp/.
- Any open space over 900 sq ft (e.g., great rooms, large garages, shops) triggers a requirement for engineered plans per IRC Table R602.10.1.3 seismic bracing provisions.
- The $500 (or $100 accessory) deposit is non-refundable but is credited toward your final permit fee if the permit is approved and issued.
- Occupying a structure before final inspection approval or written Building Official authorization can trigger a fine equal to the total building permit fee, and a Certificate of Occupancy will not issue until fines/fees are paid in full (2018 IRC Sections R110.1, R113.2, R113.4).
- Applications can be started through the county's online Building Permit Portal (iworq) with PDF plan uploads, separated by project type.
- The 10-working-day review clock begins only once the application is deemed complete — incomplete applications are not accepted into the queue.
Frequently asked questions
Unincorporated Madison County requires a residential building permit (new construction / addition / accessory structure) for: Building permit required for all new residential construction, additions, basement finishes, remodels, and accessory structures in unincorporated Madison County; Septic Permit from Eastern Idaho Public Health required prior to Building Permit approval for new dwellings, or for remodels adding a bedroom/bathroom, or connecting to an existing septic system; Recorded Warranty Deed (obtainable from the Madison County Clerk's Office); if applicant is not the legal owner, a notarized Affidavit of Legal Interest is required; Site Plan showing setbacks, well, septic, property lines, and driveway(s); Copy of the Building Contractor's State of Idaho Registration, unless the project is owner-built; One electronic copy (PDF) and/or one physical copy of plans, drawn to scale (minimum 1/8" = 1'-0"), formatted on 11"x17" paper, including: cross sections, elevations, full foundation drawing, window & door schedule, engineered truss design, engineered floor layout design; Open spaces exceeding 900 sq ft require engineered plans per IRC Table R602.10.1.3 (seismic bracing), as determined by the Building Official; Preliminary Elevation Certificate required before permit issuance if property is in a designated floodplain; Final Elevation Certificate required before Certificate of Occupancy; Driveway Access Permit from the Madison County Road & Bridge Office; Copy of subdivision covenants, if applicable; Energy code compliance via prescriptive method (Prescriptive Path form in application) or REScheck analysis (Climate Zone 6B); Non-refundable Permit Fee Deposit due at submittal: $100 for accessory structures, $500 for non-accessory structures (including dwellings) — applied toward the total permit fee if approved; Additional approvals may be required: Administrative Permit/ADU approval from Planning & Zoning (for more than one dwelling unit on a parcel), Fire Marshal review for properties with significant slopes, Army Corps of Engineers permits for wetlands, Road & Bridge/Corps approval for bridges; Electrical and plumbing work requires a SEPARATE permit through the City of Rexburg Building Department (contracted electrical inspection authority per I.C. 54-1001) — NOT issued by Madison County. If your project isn't listed, confirm with Madison County Building Department at 208-359-6262 before starting work.
A non-refundable deposit is due at application submittal: $500 for dwellings and other non-accessory structures, or $100 for accessory structures. The deposit is applied toward the total permit fee if the permit is approved and issued. Source: Madison County Building Permit Application (Fillable v2, updated 2026-01-22).
The review process requires a minimum of ten (10) working days, beginning after all required documents have been submitted and the application is deemed complete. Source: Madison County Building Permit Application, and Building Permit page at madisoncountyid.gov/departments/building_department/building_permit/.
You'll need: Building Permit Application (Fillable v2, updated 2026-01-22); Site Plan; Septic Permit (Eastern Idaho Public Health); Recorded Warranty Deed; Driveway Access Permit. Depending on your project, Unincorporated Madison County may also ask for: Building Contractor State Registration; Preliminary/Final Elevation Certificate. See the required-documents checklist on this page for details on each.
Unincorporated Madison County requires 3 inspection(s) for a residential building permit (new construction / addition / accessory structure), in order: Footing/Foundation, Framing, Final. Schedule each through Madison County Building Department (208-359-6262).
Apply through Madison County Building Department at 134 E Main St., Ste. 206, Rexburg, ID 83440. Phone: 208-359-6262, email: ddecker@co.madison.id.us. Office hours: Mon–Fri 9:00 AM – 5:00 PM (Madison County government offices; closed all federal holidays) — hours confirmed on the co-located Planning & Zoning Dept page (134 E Main St. Ste. 208); Building Department page itself does not publish separate hours. Official information: https://www.madisoncountyid.gov/departments/building_department/index.php.
Unincorporated Madison County, Idaho has adopted: 2018 International Building Code (IBC) — adopted via Madison County Code Chapter 103, Article II, Sec. 1-1, as reflected in IDAPA 24.39.30; 2018 International Residential Code (IRC) — adopted via Madison County Code Chapter 103, Article II, Sec. 2-1; 2018 International Existing Building Code (IEBC) — adopted via Madison County Code Chapter 103, Article II, Sec. 3-1; 2018 International Energy Conservation Code (IECC) — adopted via Madison County Code Chapter 103, Article II, Sec. 4-1, with local amendments to insulation/fenestration tables (Sec. 4-2); Climate Zone 6B; 2018 International Mechanical Code (IMC) — adopted via Madison County Code Chapter 103, Article II, Sec. 5-1; 2018 International Fuel Gas Code (IFGC) — adopted via Madison County Code Chapter 103, Article II, Sec. 6-1; 2018 International Fire Code (IFC) — adopted via Madison County Code Chapter 103, Article II, Sec. 7-1, as adopted by the Idaho State Fire Marshal (IDAPA 18.08.01); 2017 National Electrical Code — regulated solely by the State of Idaho per Idaho Code Title 54, Chapters 10 and 26 (county has deleted electrical provisions from its IRC per Sec. 2-2(B)); 2017 Idaho Plumbing Code — regulated solely by the State of Idaho per Idaho Code Title 54; 2013 NFPA 72 Fire Alarm & Signaling Code — referenced on Building Department resource list. Local amendments apply — see the Unincorporated Madison County overview page for the full list.
No. Madison County Code Chapter 103 Sec. 2-2(B) deletes all electrical and plumbing requirements from the county's adopted IRC, placing them solely under State of Idaho regulation (Idaho Code Title 54, Chapters 10 and 26). Madison County is contracted with the City of Rexburg to perform electrical inspections per Idaho Code 54-1001. Apply through the City of Rexburg's online permit portal. Source: Madison County Building Regulations (Chapter 103, revised 4/1/24).
Sources & verification
Verified against official sources. Last reviewed 2026-07-13.
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 Madison County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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