Building permits, zoning and septic rules in Madison County, Idaho

Yes. For projects under Madison County jurisdiction, the county requires building permits for new homes, additions, remodels, accessory structures, manufactured homes, solar work, demolition, and fire or flood repairs¹. The Building Department reviews plans and performs construction inspections¹. Incorporated cities may administer their own building permits and zoning, so confirm the correct building office for property inside city limits; Eastern Idaho Public Health still administers septic permits across Madison County^3,4. County-administered construction must comply with adopted building codes and ordinances¹. Qualifying agricultural buildings are exempt from state building codes, but Madison County may issue an agricultural-exempt permit to enforce road setbacks and utility easements⁸.

For county-administered building permits, plan review and construction inspections, contact the Madison County Building Department at 208-359-6305 or visit 134 E Main, Rexburg, ID 83440¹. Building-permit applications may be started in the county portal by project type, with plans and supporting documents uploaded as PDFs¹. Building-permit fees vary by project and permit type and may use project valuation, so request a current estimate from the Building Department¹. For county zoning approval and land-use questions, contact Madison County Planning and Zoning at 208-359-6207⁶. Mechanical, electrical and plumbing permits and inspections are handled through the City of Rexburg building department¹. Inside an incorporated city, confirm that city's building-permit and zoning process; septic permits remain with Eastern Idaho Public Health^3,4.

Madison County administers zoning in unincorporated areas, while incorporated municipalities such as Rexburg may administer their own zoning ordinances^2,3. Uses and dimensional standards depend on the parcel's jurisdiction and zoning district⁵. In the county Agricultural Zone, minimum lot width is 250 feet; the front setback is 50 feet, or 60 feet along a major or minor arterial; side and rear setbacks are 10 feet and 25 feet, with a 50-foot street-side setback for corner lots⁵. These Agricultural Zone figures do not answer the setback question in another district. Ask Madison County Planning and Zoning for an unincorporated parcel's district and approvals, or the applicable city for property inside municipal limits^5,6. We could not confirm current county rules for minimum dwelling size, lot coverage, building height, accessory dwellings, or private-land RV and tiny-home occupancy.

Eastern Idaho Public Health administers septic permits throughout Madison County, including addresses inside incorporated cities⁴. It issues septic permits for new, replacement, expanded, remodeled and repaired systems¹⁰. The application requires a plot plan, floor plans, a signed information page and payment, followed by a site evaluation; obtain the septic permit before the building permit¹⁰. Individual-system septic permits cost $900, central or large soil-absorption-system permits cost $3,000, and tank-only or vault-privy permits cost $450¹⁰. The tank and drainfield must remain uncovered for final inspection, and Eastern Idaho Public Health requires 48 hours' notice¹¹. About 42% of county soils avoid severe limitations for a conventional drain field, so keep septic feasibility as a purchase contingency¹².

We could not confirm a Madison County rule that generally allows or forbids living in an RV or tiny home on private land. In an unincorporated area, ask Madison County Planning and Zoning whether the unit is an allowed dwelling, whether temporary occupancy during construction is allowed, and which zoning approval and setbacks apply^2,6. Inside a city, ask that municipality because local zoning varies across Madison County³. Septic permits do not shift to the city: constructing, repairing or modifying an onsite sewage system generally requires an Eastern Idaho Public Health installation permit, while portable non-discharging systems are only temporary⁴. Every manufactured-home installation must be inspected and approved by the state or authority having jurisdiction before occupancy¹³.

1. Identify whether the parcel is unincorporated or inside a city; obtain county zoning approval from Madison County Planning and Zoning or city zoning approval from the applicable municipality^3,6.

1. For a private well, obtain an Idaho Department of Water Resources drilling permit and use an IDWR-licensed driller⁹.

1. Submit the septic-permit application, plot plan, floor plans, signed information page and fee to Eastern Idaho Public Health; its site evaluation and septic permit come before the building permit¹⁰.

1. Apply for the building permit through the county portal when Madison County has jurisdiction, or confirm the city process inside municipal limits^1,3.

1. Obtain mechanical, electrical and plumbing permits and inspections through the City of Rexburg building department¹.

1. Leave the septic tank and drainfield uncovered and arrange the final inspection with Eastern Idaho Public Health¹⁰.

First identify the zoning authority: Madison County handles zoning in unincorporated areas, while incorporated cities may apply different zoning rules^2,5. Request the parcel's zoning district, allowed use, zoning approval, setbacks and lot standards from Madison County Planning and Zoning or the applicable city before choosing a homesite^5,6. A private well requires an Idaho Department of Water Resources drilling permit and a licensed driller⁹. Only about 42% of county soils avoid a severe conventional-drain-field limitation, and Eastern Idaho Public Health reviews new subdivisions for wastewater suitability^12,14. The county's Fire & Flood Permit covers repairs after fire or flood damage, not the broader rules for new floodplain development¹. A state-highway driveway requires an Idaho Transportation Department encroachment permit¹⁵.