Radon Mitigation Cost in Montana (2026)
Radon in Montana: One of the Nation's Highest-Risk States
Montana is a serious radon state. The combination of uranium-bearing granite across the Rocky Mountain front, historic mining activity (especially in Butte and the surrounding region), and well-sealed homes built for cold winters creates conditions for some of the highest residential radon readings in the US.
The Montana Department of Environmental Quality estimates that more than 60% of tested Montana homes exceed the EPA action level of 4.0 pCi/L. Cities with particularly high rates include:
- Butte: Average tested levels among the highest in the country, driven by mining history and granite geology
- Helena: Consistently high — granite-rich geology throughout the valley
- Missoula: Elevated levels despite the valley location; surrounding geology and building stock drive risk
- Great Falls: Moderate-high; prairie geology with some elevated pockets
- Billings: Zone 1–2; test before assuming safe
Cost by Foundation Type
Basement: $1,000–$2,200
Montana's cold climate means most homes have basements — often unfinished or lightly finished. These are generally straightforward to mitigate.
- Unfinished basement: $1,000–$1,600
- Finished basement: $1,400–$2,200
Slab-on-Grade: $950–$1,800
Found in newer construction in Billings, Bozeman, and suburban Missoula. Typically the least expensive.
Crawl Space: $2,500–$5,500
Older Montana homes, particularly in rural areas, often have crawl spaces. Rocky terrain and cold climate can complicate access and vapor barrier installation.
Montana-Specific Cost Factors
High radon levels: Montana homes with readings above 20 pCi/L — not uncommon in Butte and Helena — often require premium fans or multiple suction points. Add $400–$900 over base pricing.
Rural contractor shortage: Montana is geographically vast with a small population. In rural areas — everything outside Billings, Missoula, Great Falls, Helena, and Bozeman — certified contractors may be scarce. Expect possible travel fees and longer wait times.
Cold climate construction: Montana homes are tightly built for winter efficiency, which tends to raise indoor radon levels. The flip side: depressurization systems work very effectively in well-sealed Montana homes.
Mining legacy: If your home is in or near a historic mining area, ask your contractor about potential additional sources beyond typical soil-gas radon.
Montana Resources
- Montana DEQ Radon Program: deq.mt.gov (search "radon")
- Verify NRPP: radonproficiency.org
- Verify NRSB: nrsb.org
Frequently Asked Questions
How bad is radon in Montana?
Montana is one of the highest-radon states in the country. More than 60% of Montana homes tested exceed the 4.0 pCi/L action level. Butte, Helena, Missoula, and Great Falls are particularly high-risk cities.
How much does radon mitigation cost in Montana?
Expect $1,000–$2,200 for slab or basement systems. Crawl space homes cost $2,500–$5,500. Contractor availability is limited in rural areas, which can increase prices.
Does Montana require radon contractor licensing?
Montana does not have a state radon contractor licensing program. Hire NRPP or NRSB certified contractors and verify credentials at radonproficiency.org or nrsb.org.
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