Bolthole Index

Custer County, Idaho

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

62Index Score / 100
#20 of 44 in Idaho

Unincorporated Custer County, Idaho uses zoning compliance and building notification tied to septic approval rather than a full code-inspected building-permit program1. No structure may go up in unincorporated Custer County without a zoning certificate from the Planning Director, and the application requires an approved septic permit first2. County zoning controls land use, lot size and building dimensions, while Eastern Idaho Public Health, not the county, issues septic permits34. Electrical, plumbing and HVAC work requires the applicable trade permits5.

At a glance

Building permit
Limited: zoning compliance and building notification tied to septic approval, not a full code-inspected county permit program1
Zoning
Yes, in unincorporated Custer County36
Septic permit
Required through Eastern Idaho Public Health for construction, modification or most repairs47
RV living
Temporary or intermittent use only, except an owner may occupy one while building a dwelling on the same property8
Tiny home
No specific occupancy rule confirmed; ask Planning and Zoning how the proposed dwelling and parcel are classified3
Owner-builder
No explicit county exemption confirmed; ask Planning and Zoning and the applicable state trade-permit office95
Minimum lot size
Varies by zoning district and utility conditions10
Private well
Obtain an IDWR drilling permit before drilling11

Who to call

Planning & zoning

Custer County Planning and Zoning

County zoning certificates, land-use questions and rural addressing

(208) 879-6894

801 E. Main Ave. #385 (FedEx or UPS), PO Box 385 (USPS), Challis, Idaho 83226-0385

Septic permits

Eastern Idaho Public Health, Custer County

Septic applications, site evaluations, permits and final inspections

(208) 522-8064

610 Clinic Road, Suite A, Challis, ID 83226

Contact details are copied from each office’s official page and were checked against it on October 10, 2026.

Off-grid gear

Going off-grid in Custer County means bringing your own water and power. The kit we’d start with:

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Do you need a building permit 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 permit212. The fee is based on square footage, and the current schedule is not published in the ordinance, so ask the office for the amount13. Unincorporated land is zoned, with district and overlay rules governing uses, dimensions and other site standards614. Electrical, plumbing and HVAC work requires permits under Idaho's trade programs5. New manufactured homes also require a state installation permit before work starts where no approved local building program operates, followed by approval before occupancy1516. 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 materials117.

Who handles Custer County building and zoning questions?

Custer County Planning and Zoning is the first county office for zoning certificates, parcel-use questions and rural addressing17. The office is at 801 E. Main Ave. in Challis and can be reached at (208) 879-689417. 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 district114. Separate state permits apply when the work includes electrical, plumbing or HVAC systems5. Eastern Idaho Public Health is the separate contact for septic review, and Idaho's water-resources agency handles well-drilling permits411. County materials reviewed do not settle owner-builder exemptions, general inspections or occupancy certificates, so put those questions directly to Planning and Zoning before construction917.

Does Custer County have zoning?

Yes. The zoning ordinance applies in unincorporated Custer County and establishes districts, overlays, permitted uses, height and area regulations, zoning permits and enforcement provisions36. The ordinance establishes six zoning districts and overlays that add requirements where mapped14. 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 land10. Dwellings may not exceed 35 feet in any zone unless the stated special-permit or other exceptions apply18. A buyer should have Planning and Zoning identify the parcel's district and overlays before treating an advertised use as allowed1714. 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 occupiable3.

How do septic permits work in Custer County?

Eastern Idaho Public Health issues wastewater permits for Custer County and performs application review, onsite evaluation and inspection1920. A valid installation permit is required before constructing or modifying an individual or subsurface sewage system, and most repairs also require one7. Submit the application with a plot plan and building plan, then arrange the onsite evaluation before permit issuance20. 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 inspection202122. 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 home23. Eastern Idaho Public Health also reviews any new subdivision for wastewater suitability24. Site feasibility deserves early attention because only 4.1% of county soils are rated without severe limitations for a conventional septic drain field25. Public or central wastewater availability can also affect approval because the director may deny an onsite permit when those facilities are reasonably accessible26. Contact the district at its Challis office before fixing a house location, driveway or well location on the site plan20.

Can you live in an RV or tiny home in Custer County?

Custer County permits temporary or intermittent RV use under conditions, but an RV generally may not serve as a dwelling8. 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 use8. 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 location8. Floodplain use must also comply with the county flood-damage ordinance8. No specific tiny-home occupancy rule or minimum dwelling floor area was confirmed, while zoning districts and dimensional rules still apply3. Ask Planning and Zoning how a tiny home would be classified and what zoning certificate is required for the parcel17.

Building a home in Custer County: the steps in order

  1. Ask Custer County Planning and Zoning to confirm the parcel's district, overlays, allowed residential use and required zoning certificate1714.
  1. Get the septic permit first, because the zoning certificate application requires an approved septic permit2. Have Eastern Idaho Public Health review the septic application, plot plan and building plan, then complete its onsite evaluation before permit issuance20.
  1. Obtain the septic installation permit before construction, modification or covered repairs, and preserve access for the final inspection722.
  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 program515.
  1. Obtain an IDWR drilling permit before drilling a private well11.
  1. If access connects to a state highway, obtain the Idaho Transportation Department encroachment permit before work in the highway right-of-way27.

What should you check before buying land in Custer County?

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 limitation1425. Terrain narrows the easy building envelope because 21.8% of county land is at a slope of 15% or less28. 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 materials27. Budget for water separately because drilling a well requires an IDWR permit11. Floodplain development requirements remain unconfirmed, although the RV rule expressly makes floodplain RV use subject to the county flood-damage ordinance8. For carrying costs, the effective property-tax rate is about 0.3%, and the median annual property-tax bill is about $9032930.

Watch-outs

  • An RV is not a general-purpose permanent dwelling in unincorporated Custer County; owner occupancy while constructing a dwelling is a conditional exception8.
  • Only 4.1% of county soils are rated without severe limits for a conventional septic drain field, so obtain the site evaluation before committing to a house site2520.
  • County floodplain-development requirements were not confirmed; ask Planning and Zoning before disturbing land in a mapped floodplain817.

Sources

  1. Septic Permit Information Sheet (2026 county census)
  2. Septic Permit Information Sheet, quoted and re-checked
  3. Custer County Zoning Ordinance No. 2007-09 (2026 county census)
  4. Eastern Idaho Public Health - Septic (2026 county census)
  5. Frequently Asked Questions (FAQs) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  6. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  7. Septic | Eastern Idaho Public Health, quoted and re-checked
  8. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  9. Homeowner Plumbing Permit Application (2026 county census)
  10. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  11. Wells Overview (Idaho statewide rule), quoted and re-checked
  12. Custer County Planning and Zoning Zoning Certificate Application, quoted and re-checked
  13. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  14. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  15. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  16. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  17. Custer County Planning and Zoning (custercountyidaho.org)
  18. Custer County Zoning Ordinance No. 2007-09, quoted and re-checked
  19. Land Development, quoted and re-checked
  20. Eastern Idaho Public Health, Custer County (eiph.id.gov)
  21. Septic Permit Information Sheet, quoted and re-checked
  22. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked
  23. eiph.id.gov, quoted and re-checked
  24. Ordinance No. 2007-09 Zoning Ordinance, Custer County, Idaho, quoted and re-checked
  25. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  26. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked
  27. Types of Right-of-Way Encroachment Permits (Idaho statewide rule), quoted and re-checked
  28. Share of land at 15% slope or less: Bolthole Index county data
  29. Effective property tax rate: Bolthole Index county data
  30. Median property tax bill: Bolthole Index county data

Written October 10, 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.

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Compared with neighboring counties

Unlike all 6 of its neighbors, Custer County requires a building permit only in limited cases.

RuleCuster CountyLemhi CountyCamas CountyBlaine CountyButte CountyValley CountyBoise County
Building permitLimitedRequiredRequiredRequiredRequiredRequiredRequired
County zoningYesYesYesYesYesYesYes
Septic permitsEastern Idaho Public HealthEastern Idaho Public HealthSouth Central Public Health DistrictSouth Central Public Health DistrictSIPHCentral District HealthCentral District Health

County locator

Custer County in Idaho

62
County map
Custer County highlighted among the Idaho counties · colored by Index score

How Custer County scores

Seclusion89100% ev.
Self-Sufficiency36100% ev.
Admin Boringness5190% ev.
Durability37100% ev.
Property Autonomy90100% ev.
Carry Cost78100% ev.

Evidence strength: 98%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$406kTypical home
0.3%Property tax
$3,588Land / acre
21.9"Annual rain
12.5% of yrsSevere drought
0.1 / yr (+0.1)Mid-century 100°F days
24.1 daysMid-century dry spell
1.35" (+5.2%)Mid-century 1-day rain
1.21×Wildfire change factor
100%Forward climate coverage
$1,396Home insurance / yr
2.1% / yrInsurance growth
2.01%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
1,511Radius comparison (15 mi)
0.9People / sq mi
94.1%Federal land
21.8%Land at 15% slope or less
4.1%Soils rated "not limited" for septic (strict USDA rating)
119,776 acWorkable land screen
35.9%Wooded land
22.6 tonsBiomass / forest ac
38.6°FAvg temp

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Cities and towns in Custer County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Not yet researched: Clayton · Mackay

Answers from the rulebook for Custer County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Custer County rules

  • Building permitLimited

    Construction-related approvals in unincorporated Custer County where Planning and Zoning and septic approvals apply.

    • The Eastern Idaho Public Health packet states that the septic permit is required to get a building permit from Planning and Zoning.
    • The county zoning certificate application requires a filing fee, structure drawings, and an approved septic permit.
    • The county application states that the applicant is responsible for obtaining permits required by applicable federal, state, county, or other government authority.
    “No structure shall be erected, constructed, reconstructed, or altered with respect to its use after the effective date of this Ordinance, until a zoning certificate has been secured from the Planning Director.”
  • County-wide zoningPresent (with conditions)

    Zoning regulation administered by Custer County in the unincorporated county.

    • The ordinance establishes district-specific requirements and overlays.
    • The ordinance states that more restrictive lawfully adopted rules, regulations, or ordinances govern when conflicts occur.
    “District: A portion of the unincorporated territory of the county within which certain uses of land, premises and buildings are permitted and certain other uses of land, premises and buildings are not permitted.”
  • Zoning districtsPublished (with conditions)

    Published zoning districts and district regulations in unincorporated Custer County.

    • The ordinance establishes six zoning districts and overlays.
    • District-specific requirements include uses, lot sizes, height, setbacks, and performance standards.
    “The following zoning districts are hereby established. For the interpretation of this Ordinance, six zoning districts and overlays have been formulated to realize the general purposes as set forth in this Ordinance.”
  • Minimum lot sizeSpecified

    Lots and parcels in Custer County zoning districts.

    • Agricultural Zone A: 20 acres, with stated historic-parcel lot-split rules and exceptions.
    • Transitional Agricultural: 2.5 acres.
    • Residential: 9,000 square feet if a proper septic system exists.
    • Industrial: 1 acre.
    • Commercial: 9,000 square feet if central water and sewer are provided and approved by the District 7 Health District.

    Agricultural minimum lot size: 20 acres (Historic parcels may qualify for lot splits ranging from 2.5 to 7 acres under stated conditions.) · Transitional Agricultural minimum lot size: 2.5 acres · Residential minimum lot size: 9000 square feet (If proper septic system; central water and sewer condition stated in footnote 2.) · Industrial minimum lot size: 1 acre · Commercial minimum lot size: 9000 square feet (If central water and sewer are provided and approved by the District 7 Health District.)

    “Transitional Agricultural 35 ft. 2.5 acres (fn. 1) Residential 35 ft. 9,000 sq. ft. – if proper septic system (fn. 2) Industrial No limitation 1 acre Commercial No limitation 9,000 sq. ft. (fn. 2)”
  • Building heightSpecified

    Building and dwelling height in Custer County zoning districts.

    • The ordinance states that dwellings may not exceed 35 feet in any zone.
    • A special conditional-use permit may authorize greater height subject to fire, aviation, view, light-and-air, and environmental considerations.
    • Specified appurtenances not intended for human occupancy are generally excepted, unless they create an aviation hazard.
    • Residential height may be modified by slope under the ordinance.

    dwelling maximum height: 35 feet (The ordinance provides conditional and slope-related modifications.)

    “Dwellings shall not exceed 35 feet in ANY zone. (Ordinance 2016-01)”
  • Living in an RVLimited

    Temporary or intermittent recreational-vehicle use in Custer County zoning jurisdiction.

    • The RV must have current registration and remain serviceable; it may not be set on blocks with tires or running gear removed.
    • No decks or additions may be attached and the RV may not be skirted.
    • The RV may not be used as a dwelling; owners must have a primary residence other than the RV, and there may be no mail service.
    • An RV may be used as a dwelling by property owners during construction of a dwelling on the same property; after completion or expiration of the residence zoning certificate, use reverts to temporary or intermittent use.
    • The RV must connect to an East Idaho Public Health-compliant sewage system or be self-contained and removed to empty holding tanks at an approved location.
    • The RV may not be used as a rental property.
    • RV use in floodplains must comply with the Flood Damage Prevention Ordinance.
    “The RV shall not be used as a dwelling. The owners must have a primary residence other than the RV.”
  • Who permits septicLocal

    Septic permitting, onsite evaluations, and inspections for Custer County through Eastern Idaho Public Health.

    • Eastern Idaho Public Health serves Custer County and the listed surrounding counties.
    “Serving Bonneville, Clark, Custer, Fremont, Jefferson, Lemhi, Madison, and Teton Counties”
    One more reviewed finding on this topic
    • Local (with conditions) — Custer County septic permitting and review administered by Eastern Idaho Public Health.
      “Custer Amy Shaw AShaw@EIPH.Idaho.gov (208) 533-3175”
  • Septic permitRequired

    Construction, modification, or repair of individual or subsurface sewage disposal systems serving Custer County.

    • The rule states that portable non-discharging systems may be used temporarily.
    • Repair of individual systems is excepted when needed because of broken or clogged solid piping or electrical or mechanical malfunctions; such repair may not expand the system unless authorized.
    • The septic permit is valid for two years and may be renewed for $50.

    permit validity: 2 years (May be renewed for an additional $50.00.) · permit renewal fee: 50 USD

    “It shall be unlawful for any person to cause or to perform the modifications, repair or construction of any individual or subsurface sewage disposal system within the State of Idaho unless there is a valid installation permit authorizing that activity.”
  • Septic inspectionRequired

    Septic systems installed in Custer County under Eastern Idaho Public Health jurisdiction.

    • Inspection must occur before covering.
    • If the system is covered before inspection, it must be uncovered for inspection.
    • Eastern Idaho Public Health requires 48 hours’ notice to schedule an inspection.

    inspection notice: 48 hours

    “Final Inspection Mandatory: It is necessary to have the system inspected by an Environmental Health Specialist prior to covering in order to determine if the system was installed in accordance with the issued permit.”
  • Off-grid sanitationLimited

    Off-grid or non-discharging sanitation arrangements in Custer County.

    • Portable non-discharging systems may be used on a temporary basis.
    • Individual subsurface sewage systems generally require a valid installation permit.
    • Repairs may be performed for specified piping or electrical/mechanical malfunctions but may not expand the system without authorization.
    “The only exceptions to this rule are: 1) Portable non-discharging systems may be used on a temporary basis, and 2) individual subsurface sewage disposal systems may be repaired when needed as the result of broken or clogged solid piping or malfunctions in an electrical or mechanical system.”
  • Subdividing landRegulated (with conditions)

    Subdivision and division of land in Custer County.

    • The zoning ordinance defines subdivision as dividing a lot, tract, or parcel into five or more parts for transfer, use, or development.
    • The ordinance refers to a separate subdivision ordinance for regulations.
    • EIPH reviews new subdivisions for wastewater suitability.
    “The Environmental Health Division has regulatory responsibility to review all new subdivisions to ensure that the land is suitable for disposing of wastes in order to protect the public’s health and the environment.”
  • Permit feesVariable (with conditions)

    Custer County zoning and planning application fees.

    • The county zoning ordinance sets filing fees by resolution and states that the applicant reimburses county publication and mailing costs.
    • The zoning certificate application states that its filing fee is based on square footage.
    • The specific current fee schedule was not extracted.
    “All applications for amendment, reclassification, special use, or variances, shall be accompanied by a filing fee set by resolution causing the applicant to reimburse the County for all costs incurred in publication and/or mailing.”
  • Permit processPublished (with conditions)

    County zoning-certificate and subdivision approval processes.

    • The zoning certificate application requires a filing fee, structure drawings, and an approved septic permit.
    • Subdivision applicants must file applications and preliminary-plat data with the Commission.
    • Final plats require Commission review and Board action.
    “No structure shall be erected, constructed, reconstructed, or altered with respect to its use after the effective date of this Ordinance, until a zoning certificate has been secured from the Planning Director.”

Idaho rules that apply here

  • Owner-builder exemptionConditional

    Homeowners personally performing plumbing work on their own residential premises in Idaho.

    • The homeowner must own the residential property and personally perform the permitted work.
    • The homeowner permit is valid only for a primary or secondary residence and associated outbuildings.
    • Associated outbuildings must not be used for commercial purposes or rented by a tenant.
    • The homeowner must accept responsibility for all work performed.
    • All work must be inspected by the Division of Occupational and Professional Licensing.
    • A plumbing permit must be obtained by application to the Division.
    • The application must be submitted with payment.
    • The application form states that an additional $65 fee may be assessed if the location is not clearly provided by directions or an attached map.
    • The application was revised 8/17/2022; this revision date is not treated as an effective date.

    unclear-location fee: 65 USD (May be assessed if the location is not clearly given by directions or an attached map.)

    “I certify that I am the owner of the residential property and will personally perform the work covered by this permit.”
    4 more reviewed findings on this topic
    • Available — An owner performing their own construction work on the owner's own land in Idaho.
      “A: Any person who engages in a construction job with a dollar amount exceeding $2000.00 (materials & labor) and is not otherwise exempt (The exemptions are listed below); [...] Owners: Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — An Idaho homeowner undertaking construction or trade work for which a state-administered permit process applies.
      “Public (Homeowners Only) [...] *Public: “Homeowner” is pre-selected. [...] Once payment is processed, you may choose “Request Inspection” and/or “Print Permit””
    • Conditional — Owners performing construction work on their own land in Idaho under the state contractor-registration system.
      “Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — Homeowners personally performing electrical work on a primary or secondary residence and related outbuildings in Idaho.
      “Homeowners may purchase a permit only when they themselves are doing electrical work on their primary or secondary residence and/or related outbuildings.”
  • Building code adoptedAdopted (with conditions)

    Building construction in Idaho subject to the Idaho Building Code Act and the Idaho Division of Occupational and Professional Licenses building-code program.

    • The adopted codes include amendments identified by Idaho; local-government application is subject to the Idaho Building Code Act.
    • The reference to the 2020 Edition is an identifier to the legislative session in which amendments were adopted.
    • Amendments can be made in any legislative cycle regardless of code cycle.
    • The cited DOPL page states that existing rules remain in effect for 2026–2027.

    International Building Code: 2018 edition, with amendments · International Residential Code: 2018 edition, parts I, II, III and IX, with Idaho amendments; collectively named Idaho Residential Code (2020 Edition) · International Energy Conservation Code: 2018 edition, with amendments; collectively named Idaho Energy Conservation Code (2020 Edition) · International Existing Building Code: 2018 edition

    “Building Codes: 2018 International Building Code, with amendments 2018 International Residential Code (parts I, II, III and IX), with Idaho amendments collectively named the Idaho Residential Code (2020 Edition) 2018 International Energy Conservation Code, with amendments collectively named the Idaho Energy Conservation Code (2020 Edition) 2018 International Existing Building Code”
    One more reviewed finding on this topic
    • Adopted — Statewide Idaho building-code adoption framework applicable to local governments, including counties that enforce building codes.
      “The following codes are hereby adopted for the state of Idaho division of building safety”
  • InspectionsRequired

    All manufactured-home installations in Idaho before the manufactured home is occupied.

    • The inspection and approval are performed by DOPL or the authority having jurisdiction.
    • Inspection and approval must occur before occupancy.
    “All installations must be inspected and approved by the Idaho Division of Occupational and Professional Licenses or the authority having jurisdiction before the manufactured home is occupied.”
  • Camping on your landLimited

    Camping or parking a vehicle or trailer on Idaho Fish and Game Wildlife Management Areas and access sites separate from a WMA.

    • The restriction applies in areas posted against camping or parking.
    • Leaving an unattended camp, vehicle, or trailer for more than 48 hours is prohibited without authorization.
    • Camping or parking for more than 10 days during any 30-day period on one WMA or one separate access site is prohibited without authorization.
    • The rule permits authorization by the Commission, Director, Regional Supervisor, or designee.

    unattended duration: > 48 hours (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.) · camping or parking duration: > 10 days during any 30-day period per WMA or separate access site (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.)

    “camp or park a vehicle or trailer for more than ten (10) days during any thirty (30) day period”
  • Manufactured homesLimited

    Occupancy of manufactured homes installed in Idaho.

    • For new homes in areas without an approved local building program, an installation permit and installation tag are required before installation begins.
    • All installations must be inspected and approved by DOPL or the authority having jurisdiction before the manufactured home is occupied.
    • Manufactured homes are for residential use only and are regulated under federal manufactured-housing standards plus state and local requirements.
    “An installation permit and installation tag (required only for new homes) is required by Idaho Division of Occupational and Professional Licenses prior to starting the installation in areas where there is not an approved local building program. All installations must be inspected and approved by the Idaho Division of Occupational and Professional Licenses or the authority having jurisdiction before the manufactured home is occupied.”
  • Accessory dwellingsLimited

    Accessory dwelling units for Idaho DEQ wastewater-flow and septic-system sizing purposes; this claim does not establish statewide zoning permission.

    • An ADU is sized as a single-family dwelling for the cited wastewater-flow guidance.
    • An ADU may combine flows with another structure into one system.
    • Any common septic tank must be large enough to hold the required capacity from both structures.
    • Local land-use, building, and septic authorities may impose additional requirements.

    wastewater flow basis: single-family dwelling

    “Size as a single family dwelling. Can combine with another structure's flows into one system”
  • Well permitRequired

    Construction or drilling of wells in Idaho, including domestic wells.

    • Before drilling, the well owner or driller must obtain a drilling permit from IDWR.
    • All wells must be constructed by a well driller with a valid IDWR license.
    • The separate water-right permit exemption for domestic purposes does not eliminate the drilling-permit requirement.
    • For new diversions in qualifying subdivisions filed on or after July 1, 2025, a water-right permit is required in a moratorium area, critical groundwater area, or groundwater management area, except for in-home uses and watering livestock.
    • Well construction rules apply to wells and other artificial openings more than 18 vertical feet below land surface.

    well depth threshold: > 18 vertical feet below land surface (The cited well-construction rules describe covered wells and artificial openings.) · subdivision application date: >= 2025-07-01 (Applies to qualifying new diversions described in Idaho Code § 42-227(4).)

    “Prior to drilling a well, the well owner or well driller must first obtain a drilling permit from IDWR.”
  • Mandatory utility hookupConditional

    Proposed individual or subsurface sewage disposal systems where public or central wastewater treatment facilities may be available.

    • The Director may deny a septic permit when public or central wastewater treatment facilities are reasonably accessible.
    • The cited rule does not establish a universal statewide requirement to connect every property to public sewer.
    • Subsurface septic discharge remains an identified onsite disposal method.
    “Public or central wastewater treatment facilities are reasonably accessible.”
  • Driveway accessRequired

    Private and public driveways or streets connecting to Idaho state highway right-of-way.

    • An ITD encroachment permit is required for private and public approaches, including driveways and streets.
    • No activity may occur on state highway rights-of-way until the Department or a delegated local highway agency issues an approved permit, except emergency approval affecting highway operations and motorist safety may precede processing.
    • A Traffic Impact Study may be required for new or expanded development seeking direct access to a state highway when the stated thresholds are met, unless waived by the District Engineer.

    peak-hour trips for possible TIS requirement: >= 100 new trips (unless waived by the District Engineer) · daily traffic for possible TIS requirement: >= 1000 vehicles per day (unless waived by the District Engineer)

    “Encroachment permits approved by the Department are required for private and public approaches (driveways and streets), utilities and other miscellaneous encroachments.”
  • Campground & park staysLimited

    Temporary camping in Idaho State Parks administered by the Idaho Department of Parks and Recreation.

    • Camping is permitted only in designated areas.
    • Stays are limited to 14 nights in a 30-day period; the same page's FAQ separately states a 15-day limit, creating an unresolved internal discrepancy.
    • Individual-site occupancy is limited to one family unit or no more than 8 persons unless otherwise specified; companion-site and site-design restrictions apply.
    • Camping is not permitted on beaches, parking lots, or day-use facilities.
    • Check-in is at 2 p.m. for campsites and checkout is at 1 p.m.; late checkouts may incur additional fees unless prior arrangements have been made.

    state-park stay limit: 14 nights in 30 days (FAQ on the same page states 15 days in any 30-day period) · individual-site people limit: <= 8 people (one family unit or site-specific limits may apply)

    “Camping is permitted only in designated areas. [...] Stays are limited to 14 nights in a 30-day period.”
  • county zoning authorityGeneral

    Idaho counties adopting zoning for unincorporated areas through their boards of county commissioners.

    • A board of county commissioners is a governing board and may exercise the powers authorized by the Local Land Use Planning Act.
    • The county board's powers under the chapter apply to the unincorporated area of the county.
    • Zoning must be adopted, amended, or repealed by ordinance using the notice and hearing procedures in Idaho Code § 67-6509.
    • Zoning districts must conform to the adopted comprehensive plan.
    • Within zoning districts, standards may regulate or restrict building height, number of stories, size, construction, reconstruction, alteration, repair or use of buildings and structures; lot occupancy; courts, yards and open spaces; population density; and building and structure location and use.
    • Standards must be uniform for each class or kind of building throughout each district, but may differ between districts.
    • Overlay zoning districts require clear and objective standards and must not constitute a regulatory taking under Idaho or federal law.
    “The powers of the board of county commissioners conferred by this chapter shall apply to the unincorporated area of the county.”
  • county building authorityGeneral

    Idaho counties' authority to adopt and enforce building codes and require permits for residential construction in unincorporated areas when the county operates a building-code enforcement program.

    • The statute defines local government as any city or county of Idaho.
    • A local government that had not previously implemented a code-enforcement program may elect to implement one by ordinance evidencing its intent to do so.
    • Construction in a local-government jurisdiction enforcing building codes requires a permit under the applicable local ordinance.
    • A local government issuing permits and performing enforcement must adopt the specified state-adopted codes and may amend them only within the limits stated in Idaho Code § 39-4116(4).
    • Local amendments must generally provide at least an equivalent level of protection; accessibility amendments are restricted, and additional residential-code amendments require the statutory good-cause, necessity, ordinance, public-hearing, publication, and notice procedures.
    • Single-family homes and multiple-family dwellings up to two units are exempt from automatic fire-sprinkler requirements in the enumerated codes.
    • Agricultural buildings must be exempted; a county may issue farm-building permits only for road setbacks and utility easements, at no more than actual issuance cost.
    • Permits are governed by the laws in effect when the application is received.
    • The state division retains jurisdiction for in-plant inspections and installation standards for manufactured or mobile homes and for in-plant inspections and enforcement of modular-building and commercial-coach construction standards.
    “"Local government" means any city or county of this state.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Certificate of occupancy — Certificates of occupancy for unincorporated construction.
  • Minimum dwelling size — Minimum dwelling size in unincorporated Custer County.
  • Lot coverage — Lot coverage in unincorporated Custer County.
  • Tiny homes — Tiny-home occupancy in unincorporated Custer County.
  • Agricultural exemption — Agricultural exemptions from Custer County development or construction requirements.
2 more unanswered
  • Building in a floodplain
  • Short-term rentals

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Living off-grid in Custer County, Idaho

Is Custer County a good place to live off-grid or homestead?

Custer County scores 62/100 on the Bolthole Index, a solid county profile. Its strengths: a stronger property-autonomy legal backdrop and deep seclusion — about 1,511 people within 15 miles. Watch-outs: thin water margin (21.9″/yr rainfall) and elevated current hazard exposure.

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

Custer County requires a building permit only in limited cases (such as floodplains or specific zones), and it enforces county zoning. Onsite septic is permitted by Eastern Idaho Public Health. Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

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

Living in an RV on your own land in Custer County is limited to specific cases: Temporary or intermittent recreational-vehicle use in Custer County zoning jurisdiction. The RV must have current registration and remain serviceable; it may not be set on blocks with tires or running gear removed. No decks or additions may be attached and the RV may not be skirted. Confirm with the county before relying on it.

How much does land cost in Custer County, Idaho?

Land in Custer County runs about $3,588 per acre, based on the latest county data.

What is the water situation in Custer County?

Custer County gets about 21.9" of rain a year, with severe drought in roughly 12.5% of years.

How remote is Custer County?

A typical private-land location has about 1,511 people within 15 miles and 378,055 within 100 miles. These radius catchments are the published fallback where road routing is unavailable.

How Custer compares in Idaho

Compare side-by-side →See all 44 Idaho counties ranked →