Bolthole Index

Carbon County, Montana

Zoning, building permits and septic rules in Joliet, Montana

The Town of Joliet in Carbon County, Montana has a zoning code of its own1. Joliet does not run a local building code, so construction inside town limits falls under Montana's state Building Codes Program2. Septic is separate: a Carbon County Environmental Health drainfield permit is still required3. We could not confirm Joliet's district rules for RVs, tiny homes or lot sizes.

At a glance

Zoning
Joliet has a zoning code of its own1
Building code
State-enforced; Joliet has no local building code2
Septic permit
Drainfield permit required from the local health department3
Septic holding tanks and outhouses
Not allowed in Carbon County4
Floodplain
Permit needed in mapped flood hazard areas5
RV, tiny home, lot size, setbacks
Not confirmed; ask the Town of Joliet6

Who to call

Zoning

Town of Joliet

Town zoning information and the public parcel and zoning map

Septic permits

Carbon County Environmental Health

Septic construction authorizations, drainfield permits and inspections, including for addresses inside Joliet

(406) 446-1694

County Administration Building, 17 West 11th Street, PO Box 466, Red Lodge, MT 59068

Floodplain permits

Carbon County Floodplain Administration

Floodplain permits for construction in identified floodplains

(406) 818-0160

Carbon Conservation District, 606 W. Front St., P.O. Box 489, Joliet, MT 59041

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

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

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Does Joliet, Montana have zoning?

Yes. Carbon County's hazard mitigation plan lists a zoning code or ordinance for the Town of Joliet1. The county's own development regulations cover only unincorporated Carbon County, so they do not decide what you can do on a lot inside Joliet7.

The Town directs the public to its map for zoning and parcel information8. We could not find district names, minimum lot sizes, setbacks or rules for RVs, tiny homes and accessory dwellings in the sources we opened, so ask the Town of Joliet for the zoning code before you plan a layout. Montana law requires a municipality that zones to allow at least one accessory dwelling unit by right on a lot with a single-family home, with the Town able to charge up to $250 for a one-time review9.

Do you need a building permit in Joliet, and who issues it?

Joliet does not implement a local building code, so the State of Montana's Building Codes Program enforces the state code for construction inside town limits2. Montana law lets a town enforce its own code only through a certified local program10.

A state building permit is required before construction for certain new buildings and for alterations, additions and repairs, with exemptions such as farm and ranch buildings and private garages used by the owner11. Whether a particular house or shed inside Joliet needs one is something we could not confirm, so call the Town and the state Building Codes Program before you start. A plan review fee of 35 percent of the building permit fee is added on state permits12.

How do septic permits work inside Joliet?

Septic permits for addresses inside Joliet come from Carbon County, not the Town. A Montana DEQ or county approval statement comes first13, and the local health department drainfield permit is still required afterward3. Carbon County Environmental Health issues the Septic Construction Authorization, and a permit follows a compliant inspection14.

Only systems designed by an authorized consultant and approved by Carbon County are allowed; holding tanks, outhouses and permanent porta-potties are not4. Lots under 20 acres generally need DEQ subdivision sanitation review15. USDA rates only about 19 percent of Carbon County soils as not limited for a conventional drain field, so expect a site evaluation and possibly an engineered system16. Joliet's own water and wastewater connection rules are unconfirmed; ask the Town.

Can you live in an RV or tiny home in Joliet?

We could not confirm. Joliet's zoning code text was not available in the official sources we opened, so the Town's rules for long-term RV living, tiny homes and manufactured homes are unconfirmed. Ask the Town of Joliet before you buy a lot for that purpose6.

Carbon County's RV and campground rules apply only to unincorporated land and should not be read as Joliet's rules17. Montana law bars municipal zoning from treating manufactured housing differently from other residential units18.

Building a home in Joliet: the steps, in order

  1. Ask the Town of Joliet for the zoning district of your parcel and the code's setback, lot size and use rules8.
  2. Ask the Town and the state Building Codes Program whether your project needs a state building permit2.
  3. Check whether the parcel lies in a mapped flood hazard area; floodplain permits are handled through Carbon County's contract with Sweet Grass County5.
  4. If the parcel is under 20 acres, confirm subdivision sanitation approval with DEQ15.
  5. Apply to Carbon County Environmental Health for the Septic Construction Authorization before building septic14.
  6. Get the drainfield permit and inspection3.

What stays with Carbon County, and what to check before you buy

Septic, wells and floodplain questions involve county or state offices rather than the Town3. Wells that use 35 gallons per minute or less and no more than 10 acre-feet per year can qualify for the state's permit exception, but a Notice of Intent is required beginning in 202619.

For land outside Joliet, see the Carbon County page: Carbon County's development regulations and subdivision rules differ from the Town's. Carbon County's effective property tax rate is 0.5%20.

Watch-outs

  • Joliet's zoning districts, setbacks, lot sizes and RV rules were not available to us; get the zoning code from the Town before buying6.
  • Carbon County's development regulations apply only to unincorporated land, not inside Joliet7.
  • A Certificate of Subdivision Approval does not replace the drainfield permit21.

Sources

  1. Eastern Montana Region Hazard Mitigation Plan, Annex A: Carbon County (Town of Joliet), quoted and re-checked
  2. Eastern Montana Region Hazard Mitigation Plan, Annex A: Carbon County (Town of Joliet), quoted and re-checked
  3. deq.mt.gov (Town of Joliet), quoted and re-checked
  4. Engineering Infrastructure & Subdivisions | Montana DEQ (Town of Joliet), quoted and re-checked
  5. Eastern Montana Region Hazard Mitigation Plan, Annex A: Carbon County (Town of Joliet), quoted and re-checked
  6. Town of Joliet Montana (Town of Joliet), quoted and re-checked
  7. Carbon County Development Regulations, quoted and re-checked
  8. Town of Joliet (townofjolietmt.net)
  9. 76-2-345. Accessory dwelling units -- regulations -- restrictions, MCA (Montana statewide rule), quoted and re-checked
  10. Current Codes (Montana statewide rule), quoted and re-checked
  11. Building Permits (Montana statewide rule), quoted and re-checked
  12. bsd.dli.mt.gov (Montana statewide rule), quoted and re-checked
  13. Engineering Infrastructure & Subdivisions | Montana DEQ (Town of Joliet), quoted and re-checked
  14. Carbon County Environmental Health (carbonmt.gov)
  15. Engineering Infrastructure & Subdivisions | Montana DEQ (Town of Joliet), quoted and re-checked
  16. 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
  17. Carbon County Development Regulations, quoted and re-checked
  18. 76-2-302. Zoning districts, MCA (Montana statewide rule), quoted and re-checked
  19. Exceptions To Permit Requirements, quoted and re-checked
  20. Effective property tax rate: Bolthole Index county data
  21. Engineering Infrastructure & Subdivisions (Montana statewide rule), quoted and re-checked

Written October 24, 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.

Answers from the rulebook for Town of Joliet

Town of Joliet’s own rules

  • Local zoningPresent (with conditions)

    Land inside Joliet town limits.

    • Carbon County's official 2024 mitigation-plan regulatory-capabilities table identifies a zoning code or ordinance for Town of Joliet.
    “Zoning Code or Ordinance Yes – 2021 Yes – 2008 Yes Yes Yes Yes – 2016”
  • Zoning districtsPublished (with conditions)

    Zoning information for parcels inside Joliet town limits.

    • The Town directs the public to its public map for zoning information; the official sources opened did not provide district names or dimensional schedules.
    “See the Town of Joliet's City Limits, Zoning information and town parcel information from Carbon County​”
  • Building in a floodplainRequired

    Development within Special Flood Hazard Areas inside Joliet town limits.

    • Requirements include flood-resistant construction, elevation standards, and development restrictions within Special Flood Hazard Areas.
    • Floodplain administration for Joliet is provided through Carbon County's contract with Sweet Grass County.
    “Local floodplain management regulations are actively implemented and enforced by the jurisdiction to regulate and permit development within SFHAs.”

Rules another office applies inside Town of Joliet

Town of Joliet does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Building code adoptedAdopted (with conditions)

    Construction inside Joliet town limits, because Joliet does not implement a local building code and is subject to Montana's Building Codes Program.

    • Local jurisdictions may enforce their own building, electrical, plumbing, and mechanical codes only if certified by the State's Building Codes Program.
    • The cited plan lists 2021 International Building, Residential, Existing Building, Mechanical, Fuel Gas, Energy Conservation, Swimming Pool & Spa, and Wildland Urban Interface Codes among state-enforced codes.
    “Neither the jurisdictions nor the County implement local building codes. However, the State of Montana has adopted and enforces the following range of building codes:”
  • Who permits septicMixed (with conditions)

    Onsite wastewater serving land inside Joliet town limits.

    • DEQ sanitation approval is required for applicable subdivision facilities.
    • A local health department drainfield permit remains required even where a COSA exists.
    “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

    Installation of a drainfield for an onsite wastewater system inside Joliet town limits.

    • A COSA does not replace the required local-health-department drainfield permit.
    “Yes, even thought you have a COSA, a drainfield permit is still required by the local health department.”
  • Off-grid sanitationLimited

    Onsite drainfield sanitation inside Joliet town limits.

    • A local-health-department drainfield permit is required.
    • Applicable subdivision sanitation approval identifies the wastewater-disposal method.
    “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.”
  • Well permitLimited

    Private wells associated with subdivision sanitation approval inside Joliet town limits.

    • The well must be in the approved location or approved drilling area unless a rewrite or modified lot layout is completed.
    “The well must be drilled in the exact location shown on the Lot Layout or within the "Approved Well Drilling Area" unless a rewrite or modified lot layout is completed.”
  • Subdividing landRegulated (with conditions)

    Applicable subdivisions inside Joliet town limits.

    • DEQ review concerns sanitation facilities.
    • The cited definition includes parcels under 20 acres and parcels of any size providing two or more permanent recreational-camping-vehicle or mobile-home spaces.

    parcel size threshold: < 20 acres (Exclusive of public roadways; other statutory subdivision categories also apply.)

    “The DEQ Subdivision Program reviews divisions of land comprising less than 20 acres, as well as condominiums and recreational camping vehicle and mobile home parks, regardless of the size of the parcel where they are located.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Town of Joliet or Carbon County directly.

  • Building permit — Residential construction inside Joliet town limits.
  • Owner-builder exemption — Owner-built residences inside Joliet town limits.
  • Inspections — Residential construction inside Joliet town limits.
  • Certificate of occupancy — New residential occupancy inside Joliet town limits.
  • Minimum dwelling size — Dwellings inside Joliet town limits.
15 more unanswered
  • Minimum lot size
  • Setbacks
  • Lot coverage
  • Building height
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Septic inspection
  • Mandatory utility hookup
  • Agricultural exemption
  • Driveway access
  • Short-term rentals
  • Permit fees

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.

Unanswered questions are usually a sign that Town of Joliet publishes no rule on the point, not that none exists. Carbon County’s page lists the county offices to call.

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