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§ 02
When a permit is required
Permit triggers and exempt work for Custer County
All structures, buildings, or additions: feedlots, grain storage, signs, towers, confined feeding facilities, houses, home-based businesses, commercial businesses, bulk plants. State building permits required for certain new buildings and renovations exceeding thresholds.
Storage buildings less than 160 square feet
Agricultural structures less than 300 square feet (not intended for human habitation or commercial use)
One-story detached structures used as tool sheds, playhouses, or similar (generally under state thresholds)
- Exempt Storage buildings less than 160 square feet
- Exempt Agricultural structures less than 300 square feet (not intended for human habitation or commercial use)
- Exempt One-story detached structures used as tool sheds, playhouses, or similar (generally under state thresholds)
Required documents
- Zoning permit application
- Property survey (for setback verification on some parcels)
- Completed state building permit application with plans and specifications if required
- Architectural drawings
- Structural plans
- Site plans
- Electrical plans (if applicable)
- Plumbing plans (if applicable)
- Proof of property access
- Building code
- No local building code. State codes adopted: 2021 International Building Code (IBC), 2021 International Residential Code (IRC), 2021 International Energy Conservation Code (IECC), 2020 National Electrical Code (NEC - residential electrical only), Uniform Plumbing Code, ASME A17.1 (elevators), International Swimming Pool and Spa Code. Effective June 11, 2022. Amendments in ARM 24.301.
§ 03
Application process
Typical processing: 2-3 weeks for state plan review (if plans complete)
- 01 Contact Custer County Zoning Administrator at (406) 366-1424 to determine if a zoning permit is required
- 02 Verify property has recorded access and meets minimum acreage (1 acre minimum for Custer County unincorporated)
- 03 Obtain zoning permit application from Courthouse (431 South 10th Avenue)
- 04 Submit completed application with property survey if required (setback verification: 50 feet for 3+ acres, 25 feet for 1-3 acres, 10 feet for less than 0.5 acre)
- 05 Pay zoning permit fee
- 06 Zoning permit issued
- 07 For structures requiring state building code review: Contact Montana Building and Commercial Measurements Bureau at (406) 841-2056 or buildingcodes@mt.gov
- 08 Submit state building permit application through EBIZ.MT.GOV or mail to Bureau
- 09 State performs plan review (2-3 weeks average if plans complete)
- 10 Address plan review comments and pay fees
- 11 State building permit issued
- 12 Conduct inspections as required by state at various stages
- 13 Final approval issued upon inspection completion
Typical processing time: 2-3 weeks for state plan review (if plans complete)
§ 04
Required inspections
Scheduling and sequence
How to schedule
- Contact Custer County Zoning Administrator for zoning inspections at (406) 366-1424 (phone)
- Contact Montana Building and Commercial Measurements Bureau for state building/electrical/plumbing inspections at (406) 841-2056 or buildingcodes@mt.gov (email)
Typical sequence: Zoning: Zoning permit issued, final inspection on property. State: Plan review completed, foundation/footing inspection, framing inspection, plumbing/electrical rough-in inspection, final inspection. Septic systems inspected after installation and before backfill.
§ 05
Frequently asked
Common questions about unincorporated Custer County permits
01 Do I need a building permit in unincorporated Custer County, MT? ▸
All structures, buildings, or additions: feedlots, grain storage, signs, towers, confined feeding facilities, houses, home-based businesses, commercial businesses, bulk plants. State building permits required for certain new buildings and renovations exceeding thresholds.
02 How do I apply for a building permit in unincorporated Custer County, MT? ▸
To apply for a building permit in unincorporated Custer County, MT, follow these steps: 1. Contact Custer County Zoning Administrator at (406) 366-1424 to determine if a zoning permit is required 2. Verify property has recorded access and meets minimum acreage (1 acre minimum for Custer County unincorporated) 3. Obtain zoning permit application from Courthouse (431 South 10th Avenue) 4. Submit completed application with property survey if required (setback verification: 50 feet for 3+ acres, 25 feet for 1-3 acres, 10 feet for less than 0.5 acre) 5. Pay zoning permit fee 6. Zoning permit issued 7. For structures requiring state building code review: Contact Montana Building and Commercial Measurements Bureau at (406) 841-2056 or buildingcodes@mt.gov 8. Submit state building permit application through EBIZ.MT.GOV or mail to Bureau 9. State performs plan review (2-3 weeks average if plans complete) 10. Address plan review comments and pay fees 11. State building permit issued 12. Conduct inspections as required by state at various stages 13. Final approval issued upon inspection completion
03 How long does it take to get a building permit in unincorporated Custer County, MT? ▸
Building permit processing times in unincorporated Custer County, MT typically run 2-3 weeks for state plan review (if plans complete). Timelines can vary based on project complexity and current department workload.
04 What work is exempt from building permits in unincorporated Custer County, MT? ▸
Not all construction work requires a permit in unincorporated Custer County, MT. The following work is generally exempt: Storage buildings less than 160 square feet; Agricultural structures less than 300 square feet (not intended for human habitation or commercial use); One-story detached structures used as tool sheds, playhouses, or similar (generally under state thresholds). When in doubt, confirm with the local building department before starting work.
05 How do I schedule a building inspection in unincorporated Custer County, MT? ▸
Once your permit is issued and work reaches an inspection milestone, you can schedule a building inspection in unincorporated Custer County, MT via: Contact Custer County Zoning Administrator for zoning inspections at (406) 366-1424, Contact Montana Building and Commercial Measurements Bureau for state building/electrical/plumbing inspections at (406) 841-2056 or buildingcodes@mt.gov.
last verified March 2026
source Custer County Planning and Zoning Department ↗
entry id permits/montana/custer/unincorporated
Educational reference. Permit rules and fees change — confirm current requirements directly with Custer County Planning and Zoning Department before applying. Jaspector is not legal advice.