Stillwater County, MT Insulation Payback
Attic insulation payback for Stillwater County, MT
DOE classifies Stillwater County as climate zone 6, cold — cold enough that heating, not cooling, is what decides the bill. Its recommended attic R-value for bare joists is R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $2,107 a year in heating and cooling — a payback around 1.7 years. Hard to find a home improvement with a faster payback than this.
Where the savings come from
Of that, about $2,068/year comes from reduced heating and $39/year from reduced cooling load through the ceiling. Stillwater County beats 87% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 459 counties DOE places in zone 6, Stillwater County ranks 287th. Against Montana's own average of $2,182/year, Stillwater County runs 3% below that.
Where these numbers come from
NOAA's COLUMBUS, MT US station, 5.6 miles from Stillwater County, supplies the 7,736 HDD and 241 CDD this estimate runs on. By total degree days, Stillwater County sits at the 85th percentile nationally. DOE also classifies Stillwater County as moisture regime B (dry) - ask a local contractor whether that changes the vapor-barrier approach for this job.
If the attic isn't bare
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $307/year saved — roughly 7.4 years to break even. Topping up the attic pays for itself here.
Getting it done in Stillwater County
Get more than one quote before committing. Attic access and any needed air sealing move the price around, and most contractors won't take a job below roughly $600 regardless of size - worth asking upfront given Stillwater County's estimated $2,107/year on the line.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.