Barndominiums are widely accepted across most counties.
The Montana Department of Labor and Industry administers the state building code. Local jurisdictions serve as building code enforcement authorities. Some rural counties have limited enforcement resources.
Primary Code
Montana Building Code
Code Version
2018 IBC / 2018 IRC with MT amendments
Adoption Level
Statewide
Statewide Enforcement
Yes
Rural counties process permits quickly. Larger cities (Billings, Missoula, Great Falls) have standard timelines.
Residential
Required
Commercial
Required
Agricultural
Not Required
Size threshold: structures under 200 sq ft may be exempt.
Agricultural buildings on agricultural land are generally exempt from building permits. Montana has strong agricultural protections.
Small accessory structures under 200 sq ft typically exempt.
Snow loads are the primary concern and vary dramatically. Mountain valleys can exceed 150 psf. Western Montana has moderate seismic risk.
Wind Load
95–130 mph
moderate zone
Snow Load
30–150+ psf
Seismic
A–C
Category
Flood
FEMA Regulated
Energy Code
IECC
Version
2018 IECC with MT amendments
Energy code enforced statewide. Cold climate requirements.
License Type
No state license required
Montana does not require a state contractor license. Local jurisdictions may have registration requirements.
Front
25–30 ft
Side
5–15 ft
Rear
15–25 ft
Varies by county. Rural areas have generous setbacks.
Frost depth 36-48+ inches. Foundation design must account for extreme cold. Rocky soils in mountain areas.
Very popular. Snow load engineering critical. Heated shops need insulation.
Agricultural exemptions available. Steel barns popular for livestock and hay.
Excellent market. Widely accepted throughout the state. Heavy insulation required for energy code.
Snow load design critical. Heated garages common.
Full state building code compliance required.
HOAs uncommon outside of a few resort communities and Bozeman/Missoula suburbs. Most Montana land is unrestricted.
Flood zones along major rivers. Flash flooding in mountain drainages.
Key counties with specific permit information for Montana.
Full code enforcement. Largest city in MT.
Typical fees: $300 – $2,500
Full enforcement. Higher snow loads in surrounding mountains.
Typical fees: $300 – $2,500
Fast-growing area. Full enforcement. High snow loads.
Typical fees: $400 – $3,000
Northwest MT. Full enforcement. Heavy snow loads.
Typical fees: $300 – $2,000
Rural county. Streamlined process.
Typical fees: $150 – $1,000
Ag Exemption AvailableVerify the information above directly from these official sources. Regulations change — always confirm with your local building department before starting construction.
Disclaimer: This guide is for informational purposes only and does not constitute legal or professional advice. Building codes, permit requirements, and zoning regulations change frequently. Always verify current requirements with your local building department, planning office, or a licensed professional before starting construction. Homestead Steel Structures & Design is not a legal authority on building codes or zoning regulations. Last updated February 2026.
