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

At a glance

Building permit

Required through the Madison County Building Department¹

Zoning

Administered through the county's Unified Development Code⁷

Septic permit

Issued by Eastern Idaho Public Health⁸

RV or tiny home

Private-land occupancy rules are unconfirmed; ask Planning and Zoning⁵

Owner-builder

A county building-permit exemption could not be confirmed; ask the Building Department⁹

Agricultural buildings

Qualifying agricultural buildings are exempt from state building codes; county setback and easement permits may still apply¹⁰

Private well

Obtain an IDWR drilling permit and use an IDWR-licensed driller¹¹

Who to call

Contact details are copied from each office’s official page and were checked against it on September 29, 2026.

Do you need a building permit in Madison County, Idaho?

Yes. Madison County requires building permits, and the Building Department reviews drawings and performs on-site inspections¹¹². County-administered projects must comply with county building codes and ordinances; the county page specifically lists the 2018 International Building Code but does not establish the complete current code set². Applications can begin online, with project types for residential, accessory, agricultural and manufactured-home work and an option to upload plans and supporting documents⁶. Fees vary by project and permit type, may be based on valuation, and should be confirmed with the Building Department¹³. Idaho requires local governments to exempt qualifying agricultural buildings from the state building codes, although a county may still issue a permit for road setbacks and utility easements¹⁰.

Who issues Madison County building permits, and how do you reach them?

The Madison County Building Department is the first stop for a building permit, plan review and construction inspections¹². Call the Building Official or Building Inspector at 208-359-6305 or visit 134 E Main, Rexburg, ID 83440¹². The county's permit portal accepts applications by project type and supporting PDF documents⁶. For parcel zoning, land-use approvals and Unified Development Code questions, call Madison County Planning and Zoning at 208-359-6207 or visit 134 E Main St. Suite 208, Rexburg, ID 83440⁵. A separate county owner-builder exemption could not be confirmed, so an owner planning to self-perform work should ask the Building Department whether contractor licensing or inspection requirements change for that project⁹¹².

Does Madison County have zoning?

Madison County administers zoning through its Unified Development Code, which includes residential zoning districts⁷. The available official material does not establish that the same county rules apply to every incorporated and unincorporated parcel, so confirm the parcel's jurisdiction and zoning district with Madison County Planning and Zoning before relying on a land-use assumption⁵. The county's published materials did not confirm universal answers for minimum lot size, dwelling size, setbacks, building height, lot coverage, accessory dwellings or private-land RV occupancy. Planning and Zoning is therefore the appropriate office to ask for a parcel-specific land-use table or code interpretation⁵. For an accessory dwelling that is otherwise allowed, Idaho wastewater guidance sizes the unit as a single-family dwelling and allows combined flows only when the shared septic capacity is adequate¹⁴.

How do septic permits work in Madison County?

Eastern Idaho Public Health issues septic permits for new, replacement, expanded, remodeled and repaired systems in Madison County³. The application requires a plot plan, floor plans, a signed information page and payment, followed by an agency site evaluation; the septic permit is also required before the county building permit³. Individual-system permits are $900, central or large soil-absorption-system permits are $3,000, and tank-only or vault-privy permits are $450³. A permit is valid for two years and may be renewed for $50¹⁵. The owner or installer must arrange the final inspection, and the tank and drainfield must remain uncovered until an Environmental Health Specialist inspects them⁴. Eastern Idaho Public Health requires 48 hours' notice for the inspection¹⁶. About 42% of county soils avoid severe limitations for a conventional drain field, so keep septic feasibility as a purchase contingency¹⁷.

Can you live in an RV or tiny home on land in Madison County?

We could not confirm a Madison County rule that generally allows or forbids living in an RV or tiny home on private land. Madison County administers zoning, so the practical answer depends on the parcel's jurisdiction, district and approved use⁷. Ask Planning and Zoning whether the proposed unit counts as a dwelling, whether temporary occupancy is allowed during construction, and what setbacks or minimum sizes apply⁵. Idaho's camping limits for Wildlife Management Areas and Fish and Game access sites do not answer the private-land question¹⁸. A manufactured home is a different category: every Idaho installation must be inspected and approved by the state division or the authority having jurisdiction before occupancy¹⁹. The state's installation-permit rule applies to new manufactured homes in places without an approved local building program, so confirm the correct issuer with the county before setup²⁰¹².

Building a home in Madison County: what are the steps?

1. Ask Madison County Planning and Zoning to confirm the parcel's jurisdiction, zoning district and allowed home type⁵.

1. For a private well, obtain an Idaho Department of Water Resources drilling permit and use an IDWR-licensed driller¹¹.

1. Submit the septic application, plot plan, floor plans, signed information page and fee to Eastern Idaho Public Health; its site evaluation and permit come before the building permit³.

1. Start the county building-permit application online, choose the project type and upload plans and supporting documents⁶.

1. Ask the Building Department for a project-specific fee estimate because fees vary and may use project valuation¹³.

1. Obtain separate electrical, plumbing or HVAC permits from the authority serving the project²¹.

1. Leave the septic tank and drainfield uncovered and arrange the final inspection with Eastern Idaho Public Health⁴.

What should you check before buying land in Madison County?

Start with zoning, legal access, water, wastewater and flood exposure rather than assuming a rural parcel is buildable. Madison County has zoning, but parcel-level setbacks, minimum lot size and dwelling size were not confirmed; request those answers from Planning and Zoning⁷⁵. A private well requires an IDWR drilling permit and an IDWR-licensed driller¹¹. Only about 42% of county soils avoid a severe conventional-drain-field limitation, so make septic feasibility a purchase contingency¹⁷. The county publishes a Fire & Flood Permit for structural repairs and restoration after flood damage, but that permit does not establish the broader rules for new floodplain development; ask Planning and Zoning before buying in a mapped flood area²²⁵. A state-highway driveway needs an Idaho Transportation Department encroachment permit²³.

Watch-outs

• Madison County's private-land RV, tiny-home, minimum-size and setback rules could not be confirmed; get a parcel-specific answer from Planning and Zoning before buying or placing a unit⁵.
• Agricultural-building exemptions do not establish that a structure may be used as a dwelling or bypass parcel setbacks and utility easements¹⁰.
• A driveway connecting to an Idaho state highway requires an Idaho Transportation Department encroachment permit²³.

Sources

1. Madison County, ID - Building Department (2026 county census)
2. Building Department, quoted and re-checked
3. Septic Permit Application Packet, quoted and re-checked
4. Septic Permit Application Packet, quoted and re-checked
5. Madison County Planning and Zoning (madisoncountyid.gov)
6. Building Department, quoted and re-checked
7. Madison County Code (Unified Development Code) (2026 county census)
8. Septic, quoted and re-checked
9. (2026 county census)
10. Title 39, Chapter 41, Idaho Building Code Act, quoted and re-checked
11. Well Construction & Drilling, quoted and re-checked
12. Madison County Building Department (madisoncountyid.gov)
13. Building Department, quoted and re-checked
14. Idaho DEQ - Uncommon Wastewater Flows (Idaho statewide rule), quoted and re-checked
15. Septic, quoted and re-checked
16. Septic Permit Information Sheet, quoted and re-checked
17. Share of soils without severe limits for a conventional septic drain field (USDA SSURGO): Bolthole Index county data
18. Public Use of Department Lands and Access Areas (Idaho statewide rule), quoted and re-checked
19. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
20. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
21. Frequently Asked Questions (FAQs) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
22. Building Department, quoted and re-checked
23. Types of Right-of-Way Encroachment Permits (Idaho statewide rule), quoted and re-checked

Written September 29, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.