Bolthole Index

Carbon County, Montana

Building permits, zoning and land rules in Carbon County, Montana

66Index Score / 100
#22 of 56 in Montana

A new home in unincorporated Carbon County, Montana needs a county residential development permit, which is the county's zoning approval, but an ordinary single-family home generally needs no state building permit1,2. Septic construction authorization comes from Carbon County Environmental Health3. Red Lodge is certified to enforce the building code inside its own city limits4.

Do you need a building permit in Carbon County, Montana?

A new residential use in unincorporated Carbon County requires a county development permit.

A new residential use in unincorporated Carbon County requires a county development permit1. That county land-use approval is different from a state building permit. In Montana's jurisdiction, residential buildings with fewer than five dwelling units generally are exempt from the state building permit unless they serve transient guests2. Covered commercial, multifamily and other nonexempt projects may require state plan review, permits and inspections, unless a certified local program has jurisdiction2,7. Carbon County's standard development setbacks are 10 feet from a side lot line, 20 feet from a rear lot line and 30 feet from the front lot line or street right-of-way or easement1. A qualifying agricultural use or structure does not need the county development permit, but that exemption does not erase other applicable requirements1.

Who issues development, building and septic permits in Carbon County, and how do you reach them?

Carbon County Planning & Development is the first stop for a home or other land development at the County Administration Building in Red Lodge; call (406) 690-1933.

Carbon County Planning & Development is the first stop for a home or other land development at the County Administration Building in Red Lodge; call (406) 690-19338. The office handles residential and commercial development applications, conditional uses, subdivisions, rural addresses and county-road approach applications8. Carbon County Environmental Health handles septic construction authorization, inspection and permitting at the same building; call (406) 446-16943. Carbon County Floodplain Administration works through the Carbon Conservation District in Joliet and issues permits for construction within identified floodplains; call (406) 818-01606. For covered work under state jurisdiction, the Montana Building Codes Program handles permits and inspections7. Inside Red Lodge city limits, the city, not the county, is the building-code contact because the state lists Red Lodge as certified for building-code enforcement4. Planning & Development accepts development permit applications online and publishes a fee schedule, and the fee depends on the application type8.

Does Carbon County have zoning?

Yes.

Yes. Carbon County's development and zoning regulations apply throughout unincorporated Carbon County, while incorporated municipalities fall outside those county regulations1. The County Planning Board serves as the Zoning Commission and Board of Adjustment; residential permits receive administrative review, while larger projects and conditional uses follow additional procedures1. Development-permit projects generally use 10-foot side, 20-foot rear and 30-foot front setbacks1. Conditional uses generally use a 40-foot front setback while retaining the 10-foot side and 20-foot rear standards, and some specialized uses must sit farther back1. We could not confirm a general minimum dwelling size, lot-coverage limit or countywide minimum lot size, so ask Planning & Development about the parcel, subdivision conditions and proposed use. Private covenants can also be more restrictive than county standards1.

How do septic permits work in Carbon County?

Carbon County requires a septic Construction Authorization before installation and a permit after a compliant inspection.

Carbon County requires a septic Construction Authorization before installation and a permit after a compliant inspection3. Before applying, address the county development permit, road approach, rural address, any required floodplain permit and state sage-grouse approval3. A parcel under 20 acres generally needs Montana DEQ Certificate of Subdivision Approval before the county application; a parcel over 20 acres still needs county sanitary approval and construction authorization3. Allow 45 days for review and mailing of the Construction Authorization, and the installer must request inspection at least 48 hours before completing installation, before any backfilling3,9. Only about 19.2% of county soils are rated without severe limitations for a conventional drain field, so make septic feasibility an early purchase contingency10. Carbon County allows only consultant-designed, county-approved systems, including gray-water disposal; holding tanks, outhouses and permanent portable toilets are not allowed3.

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

In unincorporated Carbon County, an RV or travel trailer affixed to the ground counts as a dwelling, and a new residential use requires a development permit.

In unincorporated Carbon County, an RV or travel trailer affixed to the ground counts as a dwelling, and a new residential use requires a development permit1. Mobile and modular homes used as dwellings also require that development permit1. We could not confirm a rule for occupying a non-affixed RV or a tiny-home-specific rule, so ask Planning & Development before using either as housing. Sanitation is not optional: gray water must be handled by an approved system, and holding tanks, outhouses and permanent portable toilets are prohibited3. Renting multiple RV or detached-unit spaces creates a commercial campground subject to public-accommodation licensing, and an RV or mobile-home park may also require subdivision review1. The commercial-campground rule does not answer occasional private camping, which we could not confirm.

Building a home in Carbon County: the steps, in order

Ask Planning & Development to confirm the parcel's county jurisdiction, subdivision conditions and application group, then file the residential development application with a site plan.

  1. Ask Planning & Development to confirm the parcel's county jurisdiction, subdivision conditions and application group, then file the residential development application with a site plan1.
  2. Lay out the home to meet the 10-foot side, 20-foot rear and 30-foot front setbacks1.
  3. Check floodplain status; construction within an identified floodplain requires county approval6.
  4. Secure legal and physical access. New access on a county road requires an approach permit, while a state-highway approach needs Montana Department of Transportation approval1.
  5. Obtain the rural address and applicable preliminary approvals, then apply for septic construction authorization3.
  6. Determine whether the structure is exempt residential work or needs state building plans, permits and inspections2.
  7. Have the septic system inspected before completion and obtain the county permit3.

What should you check before buying land in Carbon County?

Test septic feasibility early because only about 19.2% of Carbon County soils are rated without severe limitations for a conventional drain field.

Test septic feasibility early because only about 19.2% of Carbon County soils are rated without severe limitations for a conventional drain field10. Confirm the parcel's development status, standard setbacks, legal access, floodplain and subdivision history before closing1,6. A division creating parcels under 160 acres for sale, rent or lease generally faces local subdivision review, and parcels under 20 acres generally face DEQ sanitation review; exemptions have conditions11. For water, a groundwater development at or below 35 gallons per minute and no more than 10 acre-feet per year may use Montana's permit exception, but a Notice of Intent and other conditions apply12. Carbon County averages about 17.6 inches of annual precipitation and has experienced severe drought in about 13.9% of years, so verify a lawful, practical water source10.

Watch-outs

  • A Carbon County residential development permit and a Montana state building permit are separate approvals; exemption from the latter does not eliminate the former1,2.
  • Holding tanks, outhouses and permanent portable toilets are not approved substitutes for county-authorized sanitation3.
  • A county-road approach permit and state-highway approval are different processes; identify who controls the road before applying1.
  • Short-term rentals of under 30 days need a state public accommodation license and a Carbon County Environmental Health plan review, which carries a one-time $150 fee13.

Sources

13 official pages, each quoted and re-checked · written October 9, 2026

  1. Carbon County Development Regulations, adopted February 29, 2024
  2. Building Permits (Montana statewide rule)
  3. Environmental Health - Carbon County
  4. Certified City, County and Town Programs
  5. Montana Code Annotated, Title 37, Chapter 45, Construction Contractors (Montana statewide rule)
  6. Floodplain - Carbon County
  7. Building Permits (Montana statewide rule)
  8. Carbon County Planning & Development (carbonmt.gov)
  9. Environmental Health - Carbon County
  10. 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
  11. Carbon County Subdivision Regulations, adopted June 30, 2026
  12. Exempt Well Updates and Information (Montana statewide rule)
  13. Environmental Health - Carbon County

Written October 9, 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

Like all 4 of the neighbors with published rules, Carbon County has countywide zoning.

RuleCarbon CountyStillwater CountySweet Grass CountyYellowstone CountyPark CountyGolden Valley CountyWheatland County
Building permitNot requiredLimitedLimitedNot requiredNot requiredNot requiredNot required
County zoningYesYesYesYesYesNot publishedNot published
Septic permitsCounty Env. Health Dept.County Env. Health Dept.County Env. HealthRiverStone HealthCounty Env. Health Dept.County SanitarianCounty Env. Health

County locator

Carbon County in Montana

66
County map
Carbon County highlighted among the Montana counties · colored by Index score

How Carbon County scores

66 / 100 · #22 of 56 in Montana · six factors, land price, tax, rain and climate

Seclusion83100% ev.
Self-Sufficiency3998% ev.
Admin Boringness7168% ev.
Durability37100% ev.
Property Autonomy83100% ev.
Carry Cost73100% ev.

Evidence strength: 94%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$523kTypical home
0.5%Property tax
$1,923Land / acre
17.6"Annual rain
13.9% of yrsSevere drought
3.3 / yr (+3)Mid-century 100°F days
17.9 daysMid-century dry spell
1.36" (+5.8%)Mid-century 1-day rain
1.26×Wildfire change factor
100%Forward climate coverage
$2,128Home insurance / yr
2% / yrInsurance growth
1.29%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
202,962People within 2 hr
5,349Radius comparison (15 mi)
5.6People / sq mi
44%Federal land
64.8%Land at 15% slope or less
19.2%Soils rated "not limited" for septic (strict USDA rating)
165,447 acWorkable land screen
19.1%Wooded land
17.8 tonsBiomass / forest ac
43.1°FAvg temp

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Cities and towns in Carbon 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 covered: Town of Bearcreek

Answers from the rulebook for Carbon County

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

Carbon County rules

  • County-wide zoningPresent (with conditions)

    Carbon County development and zoning regulations in unincorporated Carbon County.

    • The regulations expressly apply to all unincorporated areas of Carbon County, not incorporated municipalities.
    • A Development Permit or Conditional Use Permit is required for specified changes, intensifications, residential uses, commercial uses, multifamily uses, and conditional uses.
    • Agricultural uses and structures, and accessory uses or structures meeting the stated requirements, do not require a development permit.
    • More restrictive future county, state, or federal standards apply; private agreements are not nullified and more restrictive private standards may apply.

    adoption date: 2024-02-29

    “The area included within the jurisdiction of these Regulations and governed by them shall be all the unincorporated areas of Carbon County, Montana. [...] A Development Permit or Conditional Use Permit must be issued under these Regulations when a change in use occurs; this can mean both intensification and de-intensification.”
    2 more reviewed findings on this topic
    • Present (with conditions) — Land use and development in unincorporated Carbon County.
      “The area included within the jurisdiction of these Regulations and governed by them shall be all the unincorporated areas of Carbon County, Montana.”
    • Present (with conditions) — County development and zoning regulations in unincorporated Carbon County.
      “The area included within the jurisdiction of these Regulations and governed by them shall be all the unincorporated areas of Carbon County, Montana.”
  • Local zoningPresent (with conditions)

    County-administered local zoning and development permitting in unincorporated Carbon County.

    • The County Planning Board serves as the Zoning Commission and Board of Adjustment under the regulations.
    • Group 1 residential development permits are administratively reviewed by the Planning Director.
    • Group 2 permits and conditional uses are subject to the stated Zoning Commission and County Commissioners procedures.
    • Incorporated municipalities are outside the express jurisdiction of these county regulations.

    public-hearing notice radius for conditional uses: 500 feet · appeal period for Zoning Commission decision: 10 calendar days

    “ZONING COMMISSION : The County Planning Board is the zoning commission of Carbon County, as required in Montana Code Annotated 76-2-220. [...] The area included within the jurisdiction of these Regulations and governed by them shall be all the unincorporated areas of Carbon County, Montana.”
    One more reviewed finding on this topic
    • Present (with conditions) — Unincorporated Carbon County; incorporated-municipality rules were not researched.
      “The County Planning Board is the zoning commission of Carbon County, as required in Montana Code Annotated 76-2-220.”
  • SetbacksSpecified

    Buildings and structures subject to Carbon County Group 1 or Group 2 development-permit approval in unincorporated Carbon County.

    • Buildings or structures may not be erected on property lines or within rights-of-way or easements.
    • All buildings and structures must meet the stated side, rear, and front setbacks.
    • New County Road access requires an approach permit; state-highway approaches require Montana Department of Transportation approval.
    • The county regulations apply to unincorporated areas.

    side lot-line setback: 10 feet · rear lot-line setback: 20 feet · front lot-line or street right-of-way/easement setback: 30 feet

    “All buildings and structures shall be set back 10 feet from any side lot line, 20 feet from a rear lot line and 30 feet from the front lot line or street right of way or easement.”
    3 more reviewed findings on this topic
    • Specified — Conditional uses in unincorporated Carbon County.
      “All structures for conditional uses shall be set back 10 feet from any side lot line, 20 feet from a rear lot line and 40 feet from the front lot line or street right-of-way. Setback requirements for wind energy, telecommunication towers, and oil and gas are required to exceed this standard to eliminate potential impacts to surrounding properties or roadways.”
    • Specified — Proposed buildings and structures reviewed as development in unincorporated Carbon County.
      “All buildings and structures shall be set back 10 feet from any side lot line, 20 feet from a rear lot line and 30 feet from the front lot line or street right of way or easement.”
    • Specified — Buildings and structures reviewed under Carbon County Group 1 or Group 2 development permits.
      “All buildings and structures shall be set back 10 feet from any side lot line, 20 feet from a rear lot line and 30 feet from the front lot line or street right of way or easement.”
  • Living in an RVLimited

    Commercial campgrounds, including RV parks, primitive campgrounds, glampgrounds, and similar multiple-space rental or lease uses in unincorporated Carbon County.

    • A campground is any area, regardless of size, providing multiple spaces for rent or lease where guests occupy detached units; the definition includes RV parks, primitive campgrounds, glampgrounds, and similar terms.
    • Campgrounds must comply with ARM 37.111.12 and obtain public-accommodation licensing through Montana DPHHS and the County Environmental Health Department, as appropriate.
    • If the campground meets the statutory definition of an RV park or mobile home park, subdivision review and approval are also required.
    • These county development regulations expressly apply to unincorporated Carbon County.
    “Campground: Any area, regardless of size, that will provide multiple spaces for rent or lease where the guests occupy detached units. The term includes RV parks, primitive campgrounds, glampgrounds, and other similar terms. [...] Campgrounds must abide by 37.111.12, Administrative Rules of Montana (ARM), and obtain licensing as a public accommodation through the Montana Department of Public Health and Human Services (DPHHS) and the County Environmental Health Department, as appropriate;”
    One more reviewed finding on this topic
    • Limited — An RV used as a dwelling when affixed to the ground in unincorporated Carbon County.
      “The term dwelling shall not be deemed to include a motel or hotel, but includes a mobile home, modular home, travel trailer or RV if affixed to the ground.”
  • Manufactured homesLimited

    Mobile or modular homes used as dwellings in unincorporated Carbon County.

    • A Group 1 Development Permit is required for any new residential use.
    “The term dwelling shall not be deemed to include a motel or hotel, but includes a mobile home, modular home, travel trailer or RV if affixed to the ground.”
  • Who permits septicMixed (with conditions)

    On-site wastewater approvals in Carbon County.

    • For parcels under 20 acres, DEQ Certificate of Subdivision Approval may be required.
    • For parcels over 20 acres, Carbon County issues the sanitary Construction Authorization.
    • A Carbon County septic permit follows the required approval and inspection process.

    parcel area threshold: < 20 acres (County road frontage is not counted.) · parcel area threshold: > 20 acres (County road frontage is not counted.)

    “If your property is greater than 20 acres (not counting county road frontage) you do not need Montana DEQ approval and need only a sanitary approval (Construction Authorization) issued by Carbon County.”
    One more reviewed finding on this topic
    • Mixed (with conditions) — Onsite wastewater systems in Carbon County.
      “In order to get an initial Construction Authorization and subsequent Permit for a septic system in Carbon County, you must first have an approval statement issued by either the Montana Department of Environmental Quality (DEQ) or by Carbon County.”
  • Septic permitRequired

    On-site wastewater systems and septic construction in Carbon County.

    • Before applying for a septic Construction Authorization, the applicant must address the Carbon County Development Permit, County Road Department Road Approach Permit, rural address assignment, any necessary floodplain permit, and Montana Sage Grouse Habitat Preservation Program approval.
    • An approval statement from Montana DEQ or Carbon County is required before the initial Construction Authorization and subsequent septic Permit.
    • For property less than 20 acres, not counting county road frontage, DEQ Certificate of Subdivision Approval is generally required; after DEQ issues COSA, a County application is required.
    • For property greater than 20 acres, not counting county road frontage, DEQ approval is not required, but a Carbon County sanitary approval/Construction Authorization is required before water or wastewater facilities are constructed.
    • Only systems designed by an authorized consultant and approved by Carbon County are allowed; holding tanks, outhouses, and permanent porta-potties are not allowed.
    • Do not begin construction without a valid Carbon County Septic Construction Authorization; after inspection, a Permit to Operate is issued.
    • Applications should allow 45 days for review; Construction Authorization acquisition may take from a month to a year or more depending on parcel complexity.

    DEQ/COSA threshold: < 20 acres (County road frontage is not counted) · application review allowance: 45 days

    “Only once the above-mentioned permits have been obtained, you are ready to apply for a Septic Construction Authorization enroute to a Septic Permit. [...] Do not begin construction without a valid Carbon County Septic Construction Authorization form in your possession.”
    2 more reviewed findings on this topic
    • Required — New or replacement onsite wastewater systems in Carbon County.
      “Only once the above-mentioned permits have been obtained, you are ready to apply for a Septic Construction Authorization enroute to a Septic Permit.”
    • Required — New, replacement, or repaired on-site wastewater systems in Carbon County.
      “Do not begin construction without a valid [...] Construction Authorization”
  • Septic inspectionRequired

    Permitted septic systems in Carbon County.

    • The installer must call at least 48 hours before installation completion.
    • The permit is issued after successful and compliant inspection.
    • Inspection must occur before backfilling unless the Department gives specific permission.

    inspection notice: >= 48 hours (Before installation completion.)

    “inspected by the Department PRIOR to backfilling”
    One more reviewed finding on this topic
    • Required — Installed onsite wastewater systems in Carbon County.
      “The Installer must call at least 48 hours prior to installation completion to request an inspection. Upon successful and compliant septic system inspection, a Carbon County Septic Permit will be emailed to the address supplied in the application.”
  • Off-grid sanitationProhibited

    Holding tanks, outhouses, permanent porta-potties, and unapproved wastewater systems in Carbon County.

    • Systems, including gray-water disposal, must be designed by an authorized consultant and approved by Carbon County.
    • The quoted prohibition concerns the listed sanitation methods; other approved systems remain subject to county rules.
    “Holding tanks, outhouses [...] are not allowed in Carbon County.”
    One more reviewed finding on this topic
    • Prohibited — Holding tanks, outhouses, permanent porta-potties, and gray-water disposal associated with private onsite wastewater systems in Carbon County.
      “Please know that only systems (including gray water disposal) that are designed by an authorized consultant and approved by Carbon County are allowed. Holding tanks, outhouses, permanent porta-potties, etc. are not allowed in Carbon County.”
  • Mandatory utility hookupConditional

    Conditional-use development in unincorporated Carbon County.

    • The development must demonstrate adequate service by public and/or private utilities.
    • Written certification that utility capacity is available and adequate rights-of-way or easements have been provided may be required.
    • Utility easements or other legal rights-of-way must be provided, including for electric, telephone, and natural gas.
    • Conditional-use applications must include sewerage and water provisions in the site plan.
    • The rule does not prescribe a universal municipal water or sewer connection; private utilities may satisfy the criterion if adequate.
    “Utilities: Development shall demonstrate it will be adequately served by public and/or private utilities. Written certification that capacity is available and that adequate rights-of-way or easements have been provided may be required.”
  • Agricultural exemptionConditional

    Agricultural land-division exemptions under Carbon County subdivision review.

    • The county identifies family-conveyance and agricultural exemptions from review.
    • The county states that exemptions have restrictions and that some remain subject to DEQ review.
    • The reviewed source does not provide the full eligibility criteria for every exemption.
    “Yes, there are some property splits that are exempt from review, such as the family conveyance and agricultural exemptions. There are some restrictions on the use of exemptions. Some exemptions are still subject to DEQ review.”
    One more reviewed finding on this topic
    • Available — Agricultural uses or structures under Carbon County Development Regulations.
      “No development permit is required for any agricultural use or structure.”
  • Subdividing landRegulated (with conditions)

    Subdivision and land division in Carbon County.

    • Local subdivision review is required on all lots or tracts less than 160 acres in size.
    • DEQ review is required on all lots or tracts less than 20 acres in size.
    • Family-conveyance and agricultural exemptions exist, but some exemptions remain subject to DEQ review.
    • Minor subdivisions have five or fewer lots; major subdivisions have six or more lots.
    • Legal and physical access must be provided to each subdivision lot.

    local review threshold: < 160 acres · DEQ review threshold: < 20 acres · minor subdivision maximum: <= 5 lots · major subdivision minimum: >= 6 lots

    “Generally, there are two (2) steps, one being local subdivision review and the other being DEQ sanitary review. DEQ review is required on all lots or tracts less than 20 acres in size. Local subdivision review is required on all lots or tracts less than 160 acres in size.”
    3 more reviewed findings on this topic
    • Regulated (with conditions) — Subdivision of land within the jurisdictional area of the Carbon County governing body and the towns of Bridger, Fromberg, Bearcreek, and Joliet.
      “These regulations govern the subdivision of land within the jurisdictional area of the governing body of Carbon County, and the towns of Bridger, Fromberg, Bearcreek, and Joliet. [...] SUBDIVISION: A division of land or land so divided which creates one or more parcels containing less than 160 acres that cannot be described as a one-quarter aliquot part of a United States government section, exclusive of public roadways, in order that the title to or possession of the parcels may be sold, rented, leased, or otherwise conveyed and includes any re-subdivision and a condominium [Section 76-3-103 (16), MCA].”
    • Regulated (with conditions) — Subdivisions in Carbon County.
      “If you create one or more parcels under 160s in size for SALE, RENT, or LEASE then you are subdividing land and are subject to subdivision review. State DEQ review is required on all parcels under 20 acres”
    • Regulated (with conditions) — Subdivision of land in Carbon County.
      “Local subdivision review is required on all lots or tracts less than 160 acres in size.”
  • Driveway accessRequired

    New proposed access on a County Road for a proposed development in unincorporated Carbon County.

    • Legal and physical access must be provided to the tract.
    • Approaches on state highways require Montana Department of Transportation approval.
    “Any new proposed access on a County Road will require an approach permit. Approaches on state highways shall be approved by the Montana Department of Transportation”
  • Building in a floodplainRequired

    Construction work within identified Carbon County floodplains.

    • A Carbon County floodplain permit is required for construction work within the floodplain.
    • County development approval must conform to Carbon County floodplain regulations.
    • The development regulations state that no development may occur in the floodway.
    “The Floodplain Department regulates identified floodplains and distributes permits for construction work within the floodplain.”
    2 more reviewed findings on this topic
    • Limited — Construction work within identified Carbon County floodplains.
      “The Floodplain Department regulates identified floodplains and distributes permits for construction work within the floodplain. The Floodplain Administrator position is contracted with the Carbon County Conservation District.”
    • Required — Construction work within identified floodplains in Carbon County.
      “The Floodplain Department regulates identified floodplains and distributes permits for construction work within the floodplain.”
  • Short-term rentalsLimited

    Short-term rental properties in Carbon County.

    • Montana law requires state licensing through DPHHS.
    • Carbon County Environmental Health requires plan review and inspection for the county process.
    • Red Lodge is identified as the only city in Carbon County currently requiring additional licensure on the cited page.
    • Private water or wastewater requires the stated well testing and septic-permit documentation.

    short-term rental duration: < 30 days · plan review fee: 150 USD (One-time fee stated on the county page) · state public accommodation license: 40 USD (Yearly fee stated on the county page)

    “a person engaged in the business of conducting or operating an establishment shall annually procure a license issued by the department.”
  • Permit feesPublished (with conditions)

    Carbon County planning and development permits.

    • The county planning page publishes a Fee Schedule resource; the applicable amount depends on the permit or application type.
    • The opened page did not establish a single universal permit fee.
    “Planning & Development Regulations Development Permit Application Guidebook Comprehensive Development Regulations (Rev 2024) Fee Schedule Growth Policy 2020 Part One Zoning Petitions – Resolution 2009-16 Subdivision Regulations”
  • Permit processPublished (with conditions)

    Carbon County development and septic permitting.

    • The planning page provides online applications for residential, commercial/industrial/multifamily, conditional use, rural address, road approach, and septic permits.
    • Septic applications require prior approvals and a detailed lot layout/site plan.
    “Online Development Permit Application(s) & Payment Portal”
    One more reviewed finding on this topic
    • Published (with conditions) — Group 1 and Group 2 Development Permit applications in unincorporated Carbon County.
      “A Development Permit may be applied for by the property owner, contract purchaser, or their authorized agent. The application shall be filed with the designated County Planning Director.”

Montana rules that apply here

  • Building permitLimited

    Construction, remodeling, moving, alterations, additions, repairs, or changes of occupancy for buildings subject to Montana state building-code jurisdiction.

    • A state building permit is required before construction for certain types of new buildings and for certain alterations, additions, and repairs.
    • The state permit requirement does not apply to projects within the jurisdictional limits of a certified local government program; local requirements may apply there.
    • In the state's jurisdiction, state law exempts farm and ranch buildings; mining buildings on mining property; petroleum refineries and pulp and paper mills except office and shop buildings; residential buildings containing less than five dwelling units except when serving transient guests; and private garages and private storage buildings used for the owner's own use and not as part of a commercial enterprise or business.
    • Building permits must be issued on required projects before plumbing, mechanical, or electrical permits can be issued and before work authorized under those permits can start.
    “In Montana a state building permit is required prior to the start of construction for certain types of new buildings, and/or for alterations, additions, and repairs.”
    One more reviewed finding on this topic
    • Required — Buildings subject to Montana's Building Codes Program; local certified-jurisdiction requirements may also apply.
      “Also, since it is a violation of state law to "build" a building without a building permit, the builder (contractor) is also responsible for assuring that a building permit has been obtained before construction is started.”
  • Owner-builder exemptionConditional

    An owner working on the owner's property in Montana, including Carbon County; this is an exemption from Montana's construction-contractor licensing chapter.

    • The exemption does not apply to an owner otherwise covered by the chapter who constructs an improvement with the intention and purpose of promptly selling the improved property.
    • The promptly-selling exception does not apply if the owner continuously occupied the property as the owner's primary residence for at least the last 12 months.
    • The cited chapter concerns construction-contractor licensing and does not waive Carbon County development-permit, septic, floodplain, subdivision, or other local requirements.

    primary-residence continuous occupancy before promptly selling improved property: >= 12 months (Applies to the stated exception to the owner-working-on-property exemption.)

    “to an owner working on the owner's property, whether occupied by the owner or not, but this exemption does not apply to an owner who is otherwise covered by this chapter who constructs an improvement on the owner's property with the intention and for the purpose of promptly selling the improved property, unless the owner has continuously occupied the property as the owner's primary residence for at least the last 12 months;”
    One more reviewed finding on this topic
    • Available — An owner working on the owner's property, or an owner contracting for work performed by a registered construction contractor, under Montana's construction-contractor licensing chapter.
      “(13) to an owner working on the owner's property, whether occupied by the owner or not, but this exemption does not apply to an owner”
  • Building code adoptedAdopted (with conditions)

    Montana's uniform state building code for residential and commercial buildings statewide.

    • The currently listed codes are amended and adopted through Administrative Rules of Montana Title 24, Chapter 301.
    • Cities, counties, and towns may enforce local building codes, all or in part, only through certified local building-code-enforcement programs.
    • State-owned agencies must be permitted through the Montana Department of Labor and Industry.
    • The listed 2021 International Building, Residential, and Existing Building Codes and related codes are effective June 11, 2022; the listed ASME boiler and pressure-vessel codes are effective November 6, 2021.

    International Building Code edition: 2021 · International Residential Code edition: 2021 · effective date for listed principal codes: 2022-06-11 (ASME boiler and pressure-vessel codes listed on the official page are effective 2021-11-06)

    “In addition, the program is responsible for adopting a uniform state building code, which is enforced statewide for residential and commercial buildings across Montana.”
    3 more reviewed findings on this topic
    • Adopted (with conditions) — Building-code compliance administered under Montana's state building-code program, subject to certified local jurisdictions.
      “The designs and analysis provided by these professionals is a valuable tool to the bureau’s plan review and inspection staff in determining whether compliance with the state adopted building code has been met.”
    • Partial — Montana's statewide building-code framework for residential and commercial construction.
      “In Montana, cities, counties and towns have the option to enforce local building, electrical, plumbing, and mechanical codes, all or in part (except for state-owned agencies, which must be permitted through this Department). These local building code enforcement programs must be certified by the BC Program. The remaining cities, counties and towns that have chosen not to enforce building codes, fall under the jurisdiction of the BC Program. [...] the program is responsible for adopting a uniform state building code, which is enforced statewide for residential and commercial buildings across Montana.”
    • Adopted (with conditions) — Statewide uniform state building code (building, plumbing, electrical, mechanical) enforced by the Montana Building Codes Program
      “the program is responsible for adopting a uniform state building code, which is enforced statewide for residential and commercial buildings across montana.”
  • InspectionsLimited

    Buildings and other projects requiring permits under Montana state building-code jurisdiction; certified local governments may perform inspections within their certified jurisdictional areas.

    • The Montana Building Codes Program performs inspections for projects requiring a permit under state jurisdiction.
    • The permit holder must notify the inspector when work is ready for inspection and provide access for required inspections.
    • Cities, counties, and towns may enforce local building codes and perform inspections only through certified local government programs; remaining areas fall under the state Building Codes Program.
    “The BC Program establishes and enforces statewide codes by issuing permits and performing inspections.”
  • Certificate of occupancyLimited

    Buildings constructed in accordance with the Montana state building code or a county, city, or town building code.

    • The certificate must certify that the building conforms to the applicable building regulations.
    • The statute addresses certificates for buildings constructed under the state or local building code; it does not establish a universal certificate requirement for every structure or every occupancy.
    “A certificate of occupancy for a building constructed in accordance with the provisions of the state building code or county, city, or town building code must certify that the building conforms to the requirements of the building regulations applicable to it.”
  • Camping on your landLimited

    Overnight camping by the public along surface waters open to recreational use under the Montana stream access law, on private land without landowner permission

    • Without landowner permission or contractual arrangement, overnight camping is excluded from the public's recreational use right unless necessary for enjoyment of the surface water and the campsite meets the dwelling-distance test
    • The statute's distance test: campsite not within sight of any occupied dwelling, or more than 500 yards from any occupied dwelling, whichever is less
    • For class II waters, subsection (3) excludes overnight camping without landowner permission
    • Right of use does not grant any easement to enter or cross private property to reach the water
    • No statewide private-land camping rule located

    distance from occupied dwelling: > 500 yards (or out of sight of any occupied dwelling, whichever is less)

    “(e) overnight camping unless it is necessary for the enjoyment of the surface water and the campsite is not within sight of any occupied dwelling or the campsite is more than 500 yards from any occupied dwelling, whichever is less;”
    One more reviewed finding on this topic
  • Tiny homesLimited

    Tiny dwelling units in an unincorporated county jurisdictional area where a county board of commissioners establishes zoning regulations under 76-2-202.

    • State law leaves adoption and the content of county zoning to the board of county commissioners: it may establish zoning for part or all of an eligible jurisdictional area and may create zoning districts allowing tiny dwelling units.
    • For this county-zoning statute, a tiny dwelling unit is 350 to 750 square feet, on a permanent foundation, and used as a single-family dwelling for at least 45 days or longer.
    • Appendix Q, tiny houses, of the International Building Code as printed January 1, 2023, may govern all other requirements of a tiny dwelling unit within that size range.
    • The statute does not limit historic-district conditions, local design-review standards, existing covenants, or covenants under Title 70, chapter 17, part 2.
    • Regulations may differ by district.

    tiny dwelling unit floor area: 350 to 750 square feet (Definition applies under 76-2-202.) · single-family dwelling use duration: >= 45 days (Definition applies under 76-2-202.)

    “including the creation of zoning districts that allow tiny dwelling units.”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling units in jurisdictional areas where a Montana county has established zoning regulations under MCA Title 76, chapter 2, part 2.

    • The county zoning regulations must allow at least one accessory dwelling unit by right on a lot or parcel containing a single-family dwelling.
    • The unit may be attached, detached, or internal.
    • The county may not require owner occupancy, a familial, marital, or employment relationship between occupants, or impact fees; private restrictive covenants remain possible but cannot be required as a permit, license, or use condition.
    • A county may charge up to $250 for a one-time ADU application-review fee, in addition to usual building fees.
    • Applicable building codes, fire codes, and public-health and safety regulations still apply.
    • The county may require expedited sanitation review for an ADU on a parcel with existing public water and wastewater capacity; the 15-day expedited-review provision terminates September 30, 2029.
    • The statute applies to a county that exercises zoning powers; it does not itself create county zoning where none exists.

    maximum one-time application-review fee: <= 250 USD (Usual building fees may also be required.) · expedited sanitation review: 15 days (Parcel must have existing public water and wastewater service with capacity.)

    “In jurisdictional areas where the board of county commissioners has established zoning regulations under this part, the regulations must allow a minimum of one accessory dwelling unit by right on a lot or parcel that contains a single-family dwelling.”
    One more reviewed finding on this topic
    • Allowed (with conditions) — Accessory dwelling units in Montana municipalities that exercise zoning powers under MCA Title 76, chapter 2, part 3.
      “A municipality shall adopt regulations under this chapter that allow a minimum of one accessory dwelling unit by right on a lot or parcel that contains a single-family dwelling.”
  • Well permitLimited

    New groundwater developments in Montana using 35 gallons per minute or less and no more than 10 acre-feet per year.

    • All water uses starting after June 30, 1973, require a water right either through a water-use permit or an exception to the permitting process.
    • The development may qualify for the exception; qualification is not automatic.
    • Completed groundwater uses that meet the permit exception receive a Groundwater Certificate rather than a water permit.
    • A permitted water right is required for a combined appropriation from the same source by two or more wells or developed springs exceeding 10 acre-feet, regardless of flow rate.
    • All lots in a multi-phase subdivision must share a combined water-use limit of 10 acre-feet per year to qualify for a permit exception.
    • Beginning January 1, 2026, a water user intending to develop water use through a permit exception must file a Notice of Intent with DNRC before using water from an exempt well.
    • DNRC reviews a correct and complete Notice of Intent within 10 business days; if eligible, it authorizes the Notice of Intent and gives the user five years to complete the project, put the water to use, and file a Notice of Completion.
    • If the proposed use is not eligible, the Notice of Intent is denied and the user is directed to the water-right permit process.
    • The Notice of Intent filing fee is $400.
    • An authorized Notice of Intent expires after five years, with an opportunity for one five-year extension.

    maximum flow rate: <= 35 gpm · maximum annual volume: <= 10 acre-feet per year · Notice of Intent fee: 400 USD (Beginning January 1, 2026) · Notice of Intent review period: 10 business days (For a correct and complete Notice of Intent) · authorized Notice of Intent term: 5 years (One five-year extension opportunity is available)

    “Permit Exceptions, a.k.a. Exempt Wells: Small groundwater developments that use 35 gpm or less and do not exceed 10 acre-feet per year are known as “exempt wells” and may qualify for an exception to the water permit process.”
    2 more reviewed findings on this topic
    • Limited — Groundwater wells and other groundwater developments in Carbon County under Montana water-rights law.
      “A person is not required to apply for a permit to develop a groundwater well, spring, pit, or pond with a use of 35 gallons per minute or less, not to exceed 10 acre-feet per year (Section 85-2-306, MCA).”
    • Required — Surface-water uses and groundwater uses exceeding 35 gallons per minute or 10 acre-feet per year in Montana.
      “Water Permits: A water permit is required for all surface water use and groundwater uses over 35 gallons per minute (gpm) or 10 acre-feet per year.”
  • Shed and accessory-building permit exemptionConditional

    Private garages and private storage structures used only for the owner's own use, and farm or ranch buildings, within a county, city, or town: exempt from the state building code unless the local governing body makes it applicable

    • The exemption is from the state building code; it has no square-foot threshold in the statute (applies to such structures 'of any size').
    • Private garage or private storage structure must be used only for the owner's own use.
    • A county, city, or town legislative body may by ordinance or resolution make the state building code applicable to these structures, and then may enforce it.
    • Subsection (5) still applies state energy-conservation provisions to residential buildings, except farm and ranch buildings and private garages or storage structures attached to a residential building and used only for the owner's own use.
    • Residential buildings with fewer than five dwelling units are also excluded from state-enforced building code unless local body adopts it.
    • Current-codes page lists the 2024 IRC effective September 26, 2026; the statewide adopted-rule text I opened was a draft that does not itself state a 200 sq ft permit exemption, so no numeric IRC R105.2 threshold is claimed.
    • Local jurisdictions (certified city/county/town building programs) may apply the code and their own exemptions; not researched here.

    private garage or private storage structure size limit: any size (used only for the owner's own use)

    “the state building code, as defined in 50-60-203 (3), does not apply to: (a) residential buildings containing less than five dwelling units or their attached-to structures, any farm or ranch building of any size, and any private garage or private storage structure of any size used only for the owner's own use, located within a county, city, or town, unless the local legislative body by ordinance or resolution makes the state building code applicable to these structures”
  • Campground & park staysLimited

    Camping in Montana Fish, Wildlife & Parks public-use sites.

    • Camping is prohibited except in areas specifically designated or marked for camping.
    • A camping unit, vehicle, equipment, or personal items may not be left overnight without a person present.
    • Camping longer than 7 nights at one or more campsites in a public use area during any consecutive 30-day period is prohibited unless otherwise posted by the department.
    • Designated occupancy limits must not be exceeded.
    • Special-use-permit terms must be followed unless otherwise posted.
    • Campsites must be vacated by 1 p.m. on the day of departure; camping facilities must be vacated by 12 p.m. on the day of departure.

    maximum camping duration: <= 7 nights per consecutive 30-day period (unless otherwise posted by the department) · campsite departure time: 1 p.m. · camping-facility departure time: 12 p.m.

    “Unless otherwise posted by the department, within a public use site it is prohibited to: [...] camp at one or more campsites in a public use area for a period of longer than 7 nights during any consecutive 30-day period, beginning with the first night occupied unless otherwise posted by the department;”
    2 more reviewed findings on this topic
    • Limited — Dispersed and designated-campground temporary camping on legally accessible Montana state trust land administered by DNRC.
      “Dispersed camping is allowed on state trust land with the appropriate permit and with certain restrictions. Dispersed camping on state trust land is allowed with a Conservation License. Camping that is incidental to hunting or fishing is permitted through your conservation license, and no additional permitting is required. Group camping requires a special recreational use license. On leased or licensed land: 2 days On unleased/unlicensed land: 16 days within a 30-day period Within designated campground: 16 days within a 30-day period”
    • Limited — Dispersed and campground camping on legally accessible state trust land managed by DNRC
      “in a designated campground, the maximum stay is 16 days in a 30-day period.”
  • county zoning authorityGeneral

    Montana county boards of commissioners' authority to adopt zoning regulations, including in unincorporated portions of established jurisdictional areas.

    • The board of county commissioners must have adopted a growth policy pursuant to Title 76, chapter 1.
    • Zoning may be adopted for all or parts of the jurisdictional area in accordance with Title 76, chapter 2, part 2.
    • Within unincorporated portions of an established jurisdictional area, the board may establish zoning regulations by resolution or divide the county into zoning districts.
    • Zoning regulations may regulate the erection, construction, reconstruction, alteration, repair, location, or use of buildings or structures and the use of land.
    • An action challenging creation of a zoning district or adoption of zoning regulations must be commenced within 6 months after the board's order.
    • Regulations in one district may differ from those in other districts.
    • The statute also states that zoning regulations may not treat manufactured housing or factory-built housing units differently from other residential units, subject to the statutory presumption concerning placement.

    challenge period: 6 months (after the date of the board order creating the district or adopting the regulations)

    “For the purpose of promoting the public health, safety, morals, and general welfare, a board of county commissioners that has adopted a growth policy pursuant to chapter 1 is authorized to adopt zoning regulations for all or parts of the jurisdictional area in accordance with the provisions of this part.”
    One more reviewed finding on this topic
    • General — Montana county boards of commissioners adopting zoning regulations for all or parts of their jurisdictional areas, including unincorporated portions where the statutory prerequisites are met.
      “a board of county commissioners that has adopted a growth policy pursuant to chapter 1 is authorized to adopt zoning regulations”
  • county building authorityGeneral

    Montana counties may adopt and enforce building codes and require construction permits for residential construction in unincorporated county areas, subject to the statutory certification, geographic, code-content, and permit requirements.

    • A county may adopt a building code by ordinance or resolution, or authorize adoption by administrative action.
    • A county may adopt its building code on a countywide basis unless a city or town within the county has adopted a building code; the county may not enforce its county building code within that city or town.
    • The county code-enforcement program must be certified by the Montana Department of Labor and Industry.
    • The current adopted code, current fee list, and current enforcement plan must be filed with and approved by the Department.
    • Inspectors must satisfy the stated state-licensing or approved national-certification requirements.
    • Except for voluntary incentive-based energy-conservation standards, the county may not adopt or enforce a building code more stringent than the code adopted by the Department or required by state law.
    • The county may prohibit construction from commencing until the required permit is issued after compliance is shown.
    • The general construction-permit requirement applies to buildings subject to Title 50, chapter 60, parts 1 through 4.
    • State agency-owned buildings remain under state Department jurisdiction for plan review, permitting, and inspections.
    “The local legislative body of a county, city, or town may adopt a building code to apply to the county, city, or town by an ordinance or resolution, as appropriate: (a) adopting a building code; or (b) authorizing the adoption of a building code by administrative action.”
    One more reviewed finding on this topic
    • General — Montana counties' authority to adopt and enforce building codes and require building-code administration for construction in county areas, including unincorporated areas.
      “The local legislative body of a county, city, or town may adopt a building code to apply to the county, city, or town by an ordinance or resolution, as appropriate: (a) adopting a building code; or (b) authorizing the adoption of a building code by administrative action.”

Inside cities and towns in Carbon County

Municipal rules found while researching the county. They apply inside that city or town, not to unincorporated land.

  • Building code adoptedAdopted (with conditions)

    Building-code enforcement within Red Lodge city limits.

    • The state list identifies Red Lodge as certified for B, meaning building-code enforcement.
    “Red Lodge | B | Brian Hanna | 446-1606 | City Limits [...] Key: B= Building”

Still unanswered

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

  • Zoning districts — Published zoning districts in unincorporated Carbon County.
  • Minimum dwelling size — Minimum dwelling size in Carbon County.
  • Minimum lot size — Minimum lot size in Carbon County.
  • Lot coverage — General lot coverage in Carbon County.
  • Building height — General building height in Carbon County.

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 Carbon County, Montana

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

Carbon County scores 66/100 on the Bolthole Index, a strong county profile. Its strengths: sparse surroundings — about 5,349 people within 15 miles and a stronger property-autonomy legal backdrop. Watch-outs: elevated current hazard exposure and thin water margin (17.6″/yr rainfall).

How much does land cost in Carbon County, Montana?

Land in Carbon County runs about $1,923 per acre, based on the latest county data.

What is the water situation in Carbon County?

Carbon County gets about 17.6" of rain a year, with severe drought in roughly 13.9% of years.

How remote is Carbon County?

A typical private-land location has about 5,349 people within 15 miles and 420,876 within 100 miles. These radius catchments are the published fallback where road routing is unavailable.

How Carbon compares in Montana

Compare side-by-side →See all 56 Montana counties ranked →