Building permits, zoning and land rules in Custer County, Idaho

Custer County does not present its rural process as a full code-inspected building-permit program; the county uses a zoning compliance certificate and building notification tied to septic approval¹. That limited answer does not mean a project is permit-free: the zoning ordinance bars erecting, constructing, reconstructing or altering the use of any structure until the Planning Director issues a zoning certificate, and the application requires a filing fee, structure drawings and an approved septic permit¹. The fee is based on square footage, and the current schedule is not published in the ordinance, so ask the office for the amount¹. Unincorporated land is zoned, with district and overlay rules governing uses, dimensions and other site standards¹. Electrical, plumbing and HVAC work requires permits under Idaho's trade programs³. New manufactured homes also require a state installation permit before work starts where no approved local building program operates, followed by approval before occupancy⁶. Custer County's materials do not confirm general county building inspections or a certificate-of-occupancy requirement, so ask Planning and Zoning how the office will classify the exact project before ordering materials^1,7.

Custer County Planning and Zoning is the first county office for zoning certificates, parcel-use questions and rural addressing⁷. The office is at 801 E. Main Ave. in Challis and can be reached at (208) 879-6894⁷. Because the county process is limited rather than a full code-inspected permit program, ask the office to identify the required zoning paperwork for the proposed structure and zoning district¹. Separate state permits apply when the work includes electrical, plumbing or HVAC systems³. Eastern Idaho Public Health is the separate contact for septic review, and Idaho's water-resources agency handles well-drilling permits^2,5. County materials reviewed do not settle owner-builder exemptions, general inspections or occupancy certificates, so put those questions directly to Planning and Zoning before construction^4,7.

Yes. The zoning ordinance applies in unincorporated Custer County and establishes districts, overlays, permitted uses, height and area regulations, zoning permits and enforcement provisions¹. The ordinance establishes six zoning districts and overlays that add requirements where mapped¹. Minimum lot size therefore depends on the parcel's district and utility conditions: the cited schedule sets different standards for agricultural, transitional agricultural, residential, industrial and commercial land¹. Dwellings may not exceed 35 feet in any zone unless the stated special-permit or other exceptions apply¹. A buyer should have Planning and Zoning identify the parcel's district and overlays before treating an advertised use as allowed^1,7. Custer County's reviewed rules do not confirm a countywide minimum dwelling floor area, so ask the office about a proposed tiny home rather than assuming that a small structure is automatically occupiable¹.

Eastern Idaho Public Health issues wastewater permits for Custer County and performs application review, onsite evaluation and inspection^8,9. A valid installation permit is required before constructing or modifying an individual or subsurface sewage system, and most repairs also require one². Submit the application with a plot plan and building plan, then arrange the onsite evaluation before permit issuance⁹. The system must pass final inspection by an Environmental Health Specialist before it is covered, and a system covered too early must be uncovered; the district asks for 48 hours' notice to schedule the inspection^8,9,10. Portable non-discharging systems are allowed only on a temporary basis, so an off-grid toilet does not replace a permitted system for a permanent home². Eastern Idaho Public Health also reviews any new subdivision for wastewater suitability¹¹. Site feasibility deserves early attention because only 4.1% of county soils are rated without severe limitations for a conventional septic drain field¹². Public or central wastewater availability can also affect approval because the director may deny an onsite permit when those facilities are reasonably accessible¹³. Contact the district at its Challis office before fixing a house location, driveway or well location on the site plan⁹.

Custer County permits temporary or intermittent RV use under conditions, but an RV generally may not serve as a dwelling¹. A property owner may live in an RV while constructing a dwelling on the same property; after the residence zoning certificate is completed or expires, the RV must return to temporary or intermittent use¹. The RV must remain registered and serviceable, cannot acquire decks, additions or skirting, and must use an approved sewage system or be self-contained and taken to an approved dumping location¹. Floodplain use must also comply with the county flood-damage ordinance¹. No specific tiny-home occupancy rule or minimum dwelling floor area was confirmed, while zoning districts and dimensional rules still apply¹. Ask Planning and Zoning how a tiny home would be classified and what zoning certificate is required for the parcel⁷.

1. Ask Custer County Planning and Zoning to confirm the parcel's district, overlays, allowed residential use and required zoning certificate^1,7.

1. Get the septic permit first, because the zoning certificate application requires an approved septic permit¹. Have Eastern Idaho Public Health review the septic application, plot plan and building plan, then complete its onsite evaluation before permit issuance⁹.

1. Obtain the septic installation permit before construction, modification or covered repairs, and preserve access for the final inspection^2,10.

1. Obtain Idaho permits for electrical, plumbing and HVAC work, and obtain the state installation approval that applies to a new manufactured home where there is no approved local building program^3,6.

1. Obtain an IDWR drilling permit before drilling a private well⁵.

1. If access connects to a state highway, obtain the Idaho Transportation Department encroachment permit before work in the highway right-of-way¹⁴.

Start with zoning and septic feasibility: Custer County has mapped districts and overlays, while only 4.1% of its soils avoid a severe conventional-drain-field limitation^1,12. Terrain narrows the easy building envelope because 21.8% of county land is at a slope of 15% or less¹². Confirm legal access and identify who owns the road; a driveway connecting to an Idaho state highway requires a state encroachment permit, while the county-road approach rule was not confirmed in the reviewed materials¹⁴. Budget for water separately because drilling a well requires an IDWR permit⁵. Floodplain development requirements remain unconfirmed, although the RV rule expressly makes floodplain RV use subject to the county flood-damage ordinance¹. For carrying costs, the effective property-tax rate is about 0.3%, and the median annual property-tax bill is about $903¹².