Residential Building Permit (New Construction / Addition / Accessory Structure) in Unincorporated Madison County, Idaho

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.

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).

Madison County publishes no distinct commercial building permit or TI/remodel permit product. Its only general Building Permit Application states directly: 'This application is used for detached one- and two-family dwellings and associated accessory structures... Madison County Follows the IRC 2018 Code.' The county has adopted the 2018 IBC, which does govern commercial construction, and Planning & Zoning staff enforce both residential and commercial codes, but no commercial-specific application, fee schedule, or review timeline is published online — commercial and TI projects require contacting the Building Department directly at 208-359-6262.