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

At a glance

Building permit

No state permit for a single-family home in state jurisdiction; county development permit still required¹²

Development permit

$50 and required before construction⁶²

Zoning

Rules vary in and around Lewistown; countywide zoning could not be confirmed⁷⁴

Septic

Drainfield permit required through Fergus County Environmental Health⁸⁹

RV living

Private-land residential occupancy rule could not be confirmed; ask the Planning Office and Environmental Health⁴⁸

Tiny homes

No separate occupancy or minimum-size rule was confirmed; ask the Planning Office⁴

Owner-builder

Contractor-registration exemption available, but permits and trade rules still apply¹⁰

Water wells

File a DNRC Notice of Intent before developing a qualifying permit-exception well¹¹

Who to call

Contact details are copied from each office’s official page and were checked against it on October 9, 2026.

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

A single-family residence in the part of Fergus County served by the State Building Codes Bureau is exempt from the state building permit¹. Farm and ranch buildings are also exempt from the state building permit, but that exemption does not remove septic, subdivision, floodplain, utility or other requirements¹². The state building codes for areas under the State Building Codes Bureau include the 2024 International Building and Residential Codes, effective September 26, 2026¹³. Nonexempt buildings and alterations may need a state permit, and permitted work requires inspections¹⁴¹⁵.

Fergus County separately requires a development permit before any construction². The county charges $50 for that permit and lists $500 when construction begins before it is obtained⁶. An owner working on the owner's property may qualify for a construction-contractor registration exemption, but that exemption does not waive applicable building or trade permits and inspections¹⁰.

Who handles building and development permits in Fergus County?

Lewistown has the certified local building-code program within city limits; other parts of Fergus County fall under the State Building Codes Bureau¹⁶. Start a rural project with the Fergus County Planning Office because it handles development permits, floodplain programs, addressing, mapping and land-use questions¹⁷. The county development permit identifies property, road and floodplain limitations, assigns a physical address and supplies an encroachment permit when needed².

For a nonexempt project in state jurisdiction, submit construction plans and a Building Permit/Plan Review Application¹⁸. The state issues the permit after written responses resolve plan-review comments and the fees are paid; required plumbing, mechanical or electrical work cannot begin before the building permit is issued¹⁸. The permit holder must notify the inspector when work is ready and provide access¹⁵.

Where Lewistown or the state handles building permits, septic permits for the parcel still come from Fergus County Environmental Health⁵.

Does Fergus County, Montana have zoning?

We could not confirm a countywide zoning ordinance for Fergus County, so do not treat a rural parcel as unrestricted⁴. Local controls vary: the county describes City-County Planning Board jurisdiction in Lewistown and a surrounding county area, while Lewistown says its Planning Department handles zoning in the city and the surrounding area⁷. The Fergus County Planning Office is the first call for the governing jurisdiction because it handles land-use questions¹⁷.

Ask Planning to identify the parcel's jurisdiction before relying on assumptions about RV occupancy, tiny homes, setbacks, minimum dwelling size, lot size, lot coverage or building height; published countywide answers could not be confirmed⁴. Montana law permits county zoning only after statutory prerequisites and allows zoning for all or part of a county jurisdictional area, so statewide authority alone does not establish a rule for a Fergus County parcel¹⁹.

How do septic permits work in Fergus County?

Fergus County Environmental Health administers septic and wastewater matters and publishes a septic application and site-visit request, as-built materials, installer applications and site-evaluator applications⁵²⁰. A local drainfield permit remains required when a property already has a Certificate of Subdivision Approval⁹. The published new-system charge is $200 plus a $6 service fee for a certified installer, or $650 plus a $19.50 service fee for an owner or uncertified installer²¹.

Only about 4% of Fergus County soils are rated without severe limitations for a conventional drain field, so evaluate the site early²². Montana DEQ reviews sanitation for divisions of land smaller than 20 acres and reviews condominiums, recreational camping vehicle parks and mobile-home parks regardless of parcel size²³. The complete county inspection sequence could not be confirmed; ask Environmental Health when site visits or inspections must occur before work is covered²⁰.

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

We could not confirm a Fergus County rule that allows or prohibits long-term RV occupancy on private land⁴. We also could not confirm a separate tiny-home occupancy rule, a countywide minimum dwelling size or a countywide setback schedule⁴. Ask the Fergus County Planning Office about the exact parcel and proposed use before buying or moving a unit onsite; the office handles land-use issues¹⁷.

Sanitation remains a separate question from land use: Fergus County Environmental Health administers septic matters, and a local drainfield permit remains required even when a Certificate of Subdivision Approval exists⁸⁹. A proposed recreational camping vehicle park or mobile-home park also enters Montana DEQ subdivision review regardless of parcel size²⁴. Rules for camping at Montana Fish, Wildlife & Parks public-use sites do not answer whether someone may occupy an RV on private Fergus County land²⁵.

Building a home in Fergus County: what are the steps?

1. Ask the Fergus County Planning Office to confirm the parcel's jurisdiction, land-use constraints, floodplain status, addressing and access needs¹⁷.

1. Obtain the county development permit before construction; it identifies property, road or floodplain limitations, assigns the physical address and provides an encroachment permit when needed².

1. Have Fergus County Environmental Health evaluate the wastewater proposal and complete the septic application and site-visit process⁵²⁰.

1. Determine whether the structure is exempt from a state building permit or needs state plans, review, trade permits and inspections¹⁴¹⁸.

1. Before developing a qualifying permit-exception well, file the required Notice of Intent with DNRC; larger groundwater uses require a water permit¹¹²⁶.

1. Contact Road and Bridge about county-road access, or MDT for a new or modified approach onto a state highway²⁷²⁸.

What should you check before buying land in Fergus County?

Start with buildability: have Planning identify property, road and floodplain limitations, and ask Environmental Health about wastewater feasibility²⁵. Only about 4% of county soils are rated without severe limits for a conventional drain field, while about 58.6% of the land has a slope of 15% or less²²²⁹. Arrange parcel-level soil and water review before relying on those countywide figures²⁰¹¹.

Ask Road and Bridge about county-road access; a new or modified approach to a state highway needs a state approach permit or right-of-way agreement²⁷²⁸. Development in a designated Special Flood Hazard Area requires local review, and the county's published floodplain review fee is $500³⁰³¹. The median property-tax bill is about $1,709 per year, with an effective rate near 0.8%³²³³.

Watch-outs

• The state building-permit exemption for a rural single-family home does not remove the Fergus County development-permit requirement³⁴².
• Beginning construction before the county development permit raises the listed charge from $50 to $500⁶.
• Local land-use controls vary in and around Lewistown, while countywide zoning, private-land RV occupancy, tiny-home occupancy and dimensional standards could not be confirmed; ask the Fergus County Planning Office about the parcel⁷⁴¹⁷.
• A Certificate of Subdivision Approval does not replace the local drainfield permit⁹.

Sources

1. bsd.dli.mt.gov, quoted and re-checked
2. Fergus County Planning Office Fee Schedule, quoted and re-checked
3. Certified City, County and Town Programs, quoted and re-checked
4. Central Montana Central Region Hazard Mitigation Plan, Annex F: Fergus County (2026 county census)
5. Health Department - Environmental Health, quoted and re-checked
6. Fergus County Planning Office Fee Schedule, quoted and re-checked
7. Planning Office, quoted and re-checked
8. Health Department - Environmental Health, quoted and re-checked
9. Health Department - Environmental Health, quoted and re-checked
10. Montana Code Annotated, Title 37, Chapter 45, Construction Contractors (Montana statewide rule), quoted and re-checked
11. Exempt Well Updates and Information (Montana statewide rule), quoted and re-checked
12. bsd.dli.mt.gov, quoted and re-checked
13. Current Codes, quoted and re-checked
14. bsd.dli.mt.gov, quoted and re-checked
15. Montana Building Codes Program, quoted and re-checked
16. Certified City, County and Town Programs, quoted and re-checked
17. Fergus County Planning Office (fergusmt.gov)
18. Building Permits, quoted and re-checked
19. 76-2-201. County zoning authorized, MCA (Montana statewide rule), quoted and re-checked
20. Health Department - Environmental Health, quoted and re-checked
21. Health Department - Environmental Health, quoted and re-checked
22. 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
23. fergusmt.gov, quoted and re-checked
24. deq.mt.gov, quoted and re-checked
25. Public Use Rules and Regulations (Montana statewide rule), quoted and re-checked
26. Exempt Well Updates and Information (Montana statewide rule), quoted and re-checked
27. Fergus County Road and Bridge Department (fergusmt.gov)
28. Approach Manual for Landowners and Developers (Montana statewide rule), quoted and re-checked
29. Share of land at 15% slope or less: Bolthole Index county data
30. Stream Permitting (Montana statewide rule), quoted and re-checked
31. Fergus County Planning Office Fee Schedule, quoted and re-checked
32. Median property tax bill: Bolthole Index county data
33. Effective property tax rate: Bolthole Index county data
34. bsd.dli.mt.gov, quoted and re-checked

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.