Missoula Deck Guide: Permits, Footings, Fire, Bears (2026)

Updated October 24, 2026. This guide is general information, not legal or engineering advice. Rules change, so confirm with the agency listed before you start work.

Quick reference

Topic	What to know	Source
Footing depth	State minimum 24 in. unless local rules require more; 36 in. listed locally	MeltPlan
Ground snow load	40 psf for Missoula, from the state table	MeltPlan
City permits	Attached, over-30-inch and covered decks need one; low freestanding decks exempt	PermitMint; City of Missoula
County permits	Missoula County Building Division, outside city limits; some decks exempt since 2024	Missoula County; Seeley Swan Pathfinder
Contractors	No state trade license; contractors with employees must register with DLI	Montana DLI
Wildfire	County is in the 95th percentile of Western counties for WUI home-development risk	Headwaters Economics (CPAW)
Climate	About 14.1 in. of precipitation a year; records of 107°F and −33°F	Wikipedia

How deep do deck footings need to go?

Footings have to sit below the depth where the ground freezes, or frost can push them up. A summary of Montana's structural design rules says ARM 24.301.154 sets a minimum footing depth of 24 inches below finished grade, unless a local ordinance or local conditions require more, and it lists 36 inches as the locally accepted figure for Missoula. Because that local number comes from a third-party summary, have your builder confirm the depth with the City of Missoula or Missoula County before digging. Posts set on surface blocks are a common reason older decks lean and pull away from the house.

Do I need a permit in the city?

For most decks, yes. Montana adopted the 2021 International Residential Code statewide in 2022. Published summaries of City of Missoula requirements say a freestanding deck no more than 30 inches above grade is exempt, while attached decks (even low ones), decks more than 30 inches above grade, and covered decks need a building permit. In the city, permits go through Development Services in Community Planning, Development and Innovation, which takes applications through its online Permits and Licensing portal and reviews zoning as part of the building permit.

What about outside city limits?

The Missoula County Building Division issues building permits for structures in the county outside Missoula city limits, including Orchard Homes, Lolo and Frenchtown. In June 2024, county commissioners amended the code so that certain deck designs no longer need a building permit, along with some greenhouses and other non-habitable structures. The exemption only covers the building permit; electrical, zoning and other approvals may still apply. The county's permit guide at missoulacounty.build explains which projects qualify.

Is my lot in a floodplain?

Much of the valley lies along the Clark Fork, the Bitterroot and their tributaries. Outside the city, Missoula County requires a floodplain permit, approved by the floodplain administrator, before development in the regulatory floodplain, and its online maps reflect the FEMA maps dated March 7, 2019. The City of Missoula runs its own floodplain office for properties inside city limits.

Does Montana license deck builders?

Not as a trade. The Montana Department of Labor and Industry says all construction contractors with employees must register, and it defines a construction contractor as anyone who adds to or takes away from an improvement attached to real estate. That's a registration, not a test of skill. Ask any builder for their registration, proof of insurance, and who will pull the permit.

What does the climate do to a deck?

Missoula sits around 3,200 feet on the floor of what was Glacial Lake Missoula about 13,000 years ago. It averages about 14.11 inches of precipitation and roughly 40 inches of snow a year, with records of 107°F in June 2021 and −33°F in January 1957. Dry air and strong sun wear out wood finishes, freeze-thaw cycles work moisture into wood and fasteners, and a roof over a deck must carry a 40 psf ground snow load according to the state table.

How serious is the wildfire risk?

Headwaters Economics' Community Planning Assistance for Wildfire program places Missoula County in the 95th percentile of Western counties for risk of home development in the wildland-urban interface, with ponderosa pine, Douglas-fir and mountain grassland as the main fuels. The county adopted a Community Wildfire Protection Plan in May 2018. NFPA Firewise guidance for decks notes that wood and wood-plastic composite boards are combustible, that embers collect in board gaps and where boards rest on joists, and that the area beneath a deck should be kept noncombustible. Near trees or grass, keep needles out of the gaps and consider noncombustible materials close to the house.

What do bears have to do with decks?

Missoula Public Health says feeding wildlife or leaving attractants is prohibited within city limits, and bear-resistant garbage containers or enclosures are required inside the Missoula Bear Buffer Zone. It lists pet food, unsecured garbage and bird feeders as attractants and asks residents to feed birds only from December 1 through April 1. Don't plan to store trash or pet food on or under a deck.

Call before digging footings

Montana's call-before-you-dig law applies in town and in the country. Dial 811 and utility lines will be marked within two full business days. Private lines past your meter, such as power to a shop, aren't located by the free service.

Questions to ask a builder

Are you registered with the Montana Department of Labor and Industry, and are you insured?
Who pulls the permit, city or county, and which inspections will there be?
How deep will the footings go, and how will the ledger be fastened and flashed?
Is my lot in a floodplain or close to wildland fuels, and how does that change the design?
What does your warranty cover, and what do the material warranties cover?

Common questions

Do I need a permit to build a deck in Missoula?

Most decks do. Summaries of city rules say only freestanding decks 30 inches or less above grade are exempt; attached, taller and covered decks need a permit from Development Services. Outside the city, ask Missoula County.

Does Montana require deck builders to be licensed?

There's no trade license. Construction contractors with employees must register with the Montana Department of Labor and Industry.

How deep should deck footings be in Missoula?

State rules set a 24-inch minimum unless a local rule requires more, and a Montana code summary lists 36 inches locally. Confirm with the building department for your address.

Missoula deck guide (2026)