Sanders County, Montana Building Permit Guide

Sanders County and its three municipalities are all outside Montana’s certified local building programs, so the State Building Codes Program permits commercial buildings and residential buildings of five or more units, and smaller homes need no building permit. The local work is done by two County offices. Sanders County Land Services issues floodplain permits ($125 for a dock, $250 for other work), airport affected area permits and road encroachment permits, and Environmental Health permits and inspects both wells and wastewater systems. All three towns ask for a town permit before anything is built: a zoning compliance permit in Thompson Falls and Hot Springs, and a $35 setback compliance permit in Plains.

What needs a permit in Sanders County?

For a typical rural build, the permits that matter are the County’s sanitation, access and floodplain permits and the State’s electrical permit. A building-code permit enters only for the buildings the State regulates.

The County’s own advice to newcomers is to contact the County Sanitarian before installing a septic system, altering one or hooking up to an existing one, and preferably before buying the land.

Who issues permits in Sanders County?

Land Services administers the County’s subdivision, buildings-for-lease-or-rent, floodplain and airport affected area regulations and its road encroachment permits. Chris McComas is the Land Services Director. The office keeps a Monday to Thursday week and warns that hours may vary.

None of the three municipalities is on the State’s list of certified building programs (updated October 7, 2026), so the State is the building-code authority in all of them. What each one adds differs:

• Thompson Falls: the City Code requires the owner to apply to the City Clerk for a zoning compliance permit before locating any improvement on property inside city limits. Under the Zoning Ordinance of July 8, 2024, the zoning compliance officer is the Public Works Director or a designee approved by the Mayor, and appeals go to the Board of Adjustment within 30 days. The City’s fee schedule dated March 11, 2024 prices zoning permits at $200 for a dwelling or a commercial building, $100 for a garage or an addition to a house and $50 for a shed, deck or carport. The City has its own floodplain administrator at the City number. The code’s permit guide sends building-code questions to the State.
• Hot Springs: the Town states that it does not have building codes. A zoning compliance permit, with a $75 fee, is required before any new construction, and the application is available at Town Hall. Commercial properties are subject to State building codes and must be approved by a State inspector. The Town Code also calls for a written permit from the Town’s sewer department before plumbing work other than repairs, and a demolition permit applied for at Town Hall, with an asbestos inspection for every demolition.
• Plains: the Town Code (chapter 15.06) requires a setback compliance permit, and the plans have to be approved before any construction begins. Two copies of a site plan go to the Town Clerk with the $35 fee, and the Public Works Director reviews them and signs the permit. Buildings must stand at least 20 feet back from the street right-of-way or front of the lot, 15 feet from the back and 5 feet from each side; the east side of Railroad Avenue from Hubbard Street to Central Avenue and the west side of Lynch Street from Willis Street to Central Avenue are exempt. A variance is granted by the Town Council on the Planning Board’s recommendation, and the code refuses one to anyone who starts construction before applying.

Permit types and forms

Sanders County has no online permit portal. Forms are downloaded from the Land Services and Environmental Health pages and returned to the offices in Thompson Falls.

• Sanitation System Permit Application: one form (revised September 4, 2025) covers both wastewater systems and wells, in a short and a long version.
• Floodplain permit: the joint application, reviewed under the County’s floodplain regulations and the maps that took effect on June 5, 2012.
• Encroachment/Excavation Application: for boring under, cutting across or running parallel to a County road. Permits are valid for one year, and the contractor must carry liability insurance of at least $1,000,000 naming Sanders County as certificate holder.
• Airport affected area permit: an application and a variance form, with separate attachments for each of the three airports.
• Buildings for lease or rent: a certificate of approval application.
• Subdivision: pre-application meeting request, preliminary plat and final plat applications for 2026, under the Subdivision Regulations dated October 1, 2026.

The town permits are paper forms too. Thompson Falls takes its zoning compliance application at City Hall. Plains posts a Building Setback Compliance Application and a New Construction Pre-Application Form in the Set-Back Compliance folder of its Forms & Permits page, next to a drawing example and the Town’s flood plain map; both go to the Town Clerk. Hot Springs hands out its application at Town Hall.

Sanders County permit fees

Two County fee sheets apply: the current Land Services Fee Schedule and the Environmental Health wastewater and well schedule for 2025/2026.

The Environmental Health schedule gives $650 as the total fees for a property that requires a site evaluation. Where a State building permit is needed, the State works out the fee itself.

Town permit fees: Hot Springs charges $75 for its zoning compliance permit. Plains charges $35 for the setback compliance permit; its pre-application form lists compliance fees of $35 for a single-family residence and for a commercial project or minor subdivision of fewer than 5 lots, and $100 for a commercial project or major subdivision of more than 5 lots. Thompson Falls charges $50 to $200 by type of structure, and an after-the-fact zoning permit there costs $100 or twice the fee, whichever is greater.

Electrical, plumbing, mechanical, well and septic permits

No County or town office here is certified to issue trade permits, so electrical, plumbing and mechanical permits come from the State Building Codes Program and its inspectors.

Environmental Health is the permitting office for wells as well as septic systems. It licenses the site evaluators and installers who work on wastewater systems and publishes both lists, along with standard design drawings for each system type. Sewer service is generally available only inside Thompson Falls, Plains and Hot Springs, so a home outside those towns will generally need its own septic system and permit.

A guesthouse counts as a separate living unit for septic sizing if it has sleeping, cooking and sanitation facilities, and under the County’s December 12, 2024 memo a hot plate or microwave is enough to count as cooking facilities.

Application documents

In Thompson Falls, the zoning compliance application needs the property description, the owner’s name, a narrative description of the improvement and a sketch showing its location and its distances to the property boundaries. The applicant has to establish the property boundaries to the satisfaction of the zoning compliance officer.

In Plains, the site plan must be drawn at 1 inch to 20 feet or larger and show buildings, driveways, streets, parking, drainage, sewer and water lines, utilities and the nearest fire hydrant, which must be within 500 feet. The application form also asks for the setbacks in feet, the dimensions, square footage and height of the project, the lot size, off-street parking and whether the site is in the floodplain, with a plat or map attached.

How to apply: 6 steps in Sanders County

Inspections

Environmental Health inspects the installation of wells and wastewater systems, and its wastewater paperwork includes an as-built statement. The encroachment form carries a line for County inspection and approval of the finished work. In Hot Springs the zoning compliance officer reviews the plans and the site preparation before approving the permit. Plains requires the construction site to be staked out and the property pins marked before its Public Works inspection.

Building, electrical, plumbing and mechanical inspections are made by State inspectors under State permits; Hot Springs notes that commercial properties there must be approved by a State inspector.

Local Sanders County details that matter

Flathead Indian Reservation: 458,879 acres of the reservation lie inside Sanders County, and that land is governed by an elected Tribal Council and Tribal Chairman.

Fire protection: every fire department in the county is staffed by volunteers. The County’s booklet for rural owners recommends fire-resistant roofing and building materials and basic emergency access for homes in forested areas.

Construction access: the same booklet warns that large construction vehicles cannot use many narrow, steep roads, which adds delivery cost and time to a rural build.

Town floodplains: Plains and Hot Springs each have floodplain regulations of their own in the town code. In Plains a permit is required for work in the Town’s regulated flood hazard area and the Mayor’s office is the Flood Plain Administrator; in Hot Springs the role sits with the Town’s zoning office.

Encroachment season: the County asks permit holders to make contact if encroachment work will not be finished by October 1.

Montana building code

Montana adopts one building code, based on the 2024 International Codes from 26 September 2026; a certified local program or the state Building Codes Program enforces it, and the state code does not reach houses of fewer than five units, farm and ranch buildings or private garages unless a local government has made it apply to them. How Montana’s statewide code works

Official permitting resources for Sanders County

These are the primary sources behind this guide. Codes, fee schedules and procedures change — confirm the position for your filing date.

• Montana effective construction code editions
• Montana certified local building programs
• Montana DLI state building permit application
• Sanders County Environmental Health
• Sanders County Land Services
• Sanders County Land Services fee schedule (PDF)
• Sanders County wastewater and well fee schedule 2025/2026 (PDF)
• Sanders County Sanitation System Permit Application, short form (PDF)
• Sanders County encroachment/excavation application (PDF)
• Montana electrical permits
• City of Thompson Falls ordinances
• Town of Hot Springs permits and licenses
• Town of Plains Forms & Permits page (setback compliance application)
• Town of Plains ordinances (Title 15, setback compliance permit)
• Town of Hot Springs Town Ordinances page

Sanders County permit FAQs

Does Sanders County require a building permit?

The County issues none. A State building permit is required for commercial buildings and for residential buildings with five or more units; smaller homes, agricultural buildings and private garages are exempt.

How much is a septic permit in Sanders County?

$250 for a new or replacement system under the 2025/2026 schedule. The schedule lists total fees of $650 for a property that requires a site evaluation.

Do I need a permit to drill a well?

Yes. Environmental Health issues a well permit for a new or replacement well for $150.

How much is a floodplain permit?

$125 for a dock and $250 for other work. An after-the-fact permit is $500 plus the application fee.

Do I need a permit to build in Hot Springs?

Yes, a $75 zoning compliance permit from Town Hall before any new construction. The Town has no building codes of its own.

Do I need a permit to build in Thompson Falls?

Yes, a zoning compliance permit from the City Clerk before placing any improvement on a lot. The City’s 2024 fee schedule lists $200 for a dwelling and $50 for a shed, deck or carport. Call the City at (406) 827-3557.

Do I need a permit to build in Plains?

Yes, a setback compliance permit under the Town Code. Give the Town Clerk two copies of the site plan and the $35 fee before any construction starts; the Public Works Director signs the permit. Town Hall is at 101 W Lynch St., (406) 826-3411.

Do I need a permit for a driveway?

Yes. A driveway off a County road needs a County permit before it is built, and one off a state highway needs a Department of Transportation permit.

Simplify Sanders County permitting with Alliance Permitting

Alliance Permitting is a permit documentation and submission company in Montana. We prepare your paperwork, file it correctly and coordinate with the permitting authority through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.

This guide is provided by Alliance Permitting for general information about Sanders County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.