Garfield County, MT Insulation Payback
Garfield County attic insulation, by the numbers
Garfield County, Montana is zone 6 under DOE's climate map (Cold), which means winters that dominate the energy bill, with cooling a minor factor. An uninsulated attic there should be built up to R-60. For an attic around 1,000 square feet, closing the gap from R-2 to R-60 costs around $3,480 and saves an estimated $2,229 a year — payback in roughly 1.6 years. Topping up the attic pays for itself fast here.
Heating vs. cooling in Garfield County
Split it out and it's roughly $2,151 a year on the heating side, $79 on cooling. By estimated insulation savings, Garfield County lands in the 91th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Garfield County comes in 163rd by savings. Montana averages $2,182/year across the counties tracked here; Garfield County comes in 2% higher.
The climate data behind this
NOAA's JORDAN AP, MT US station, 4.6 miles from Garfield County, supplies the 8,043 HDD and 491 CDD this estimate runs on. That combined heating-and-cooling load ranks Garfield County 280th nationally by total degree days — the 91th percentile. One local detail the R-value alone won't tell you: Garfield County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
The smaller top-up scenario
If Garfield County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $325/year — payback about 7 years. Worth doing on the numbers alone.
Quotes and materials for this job
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 Garfield County's estimated $2,229/year on the line.
Where these figures come from
Garfield County's R-60 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-60 is the target here specifically.