Teton County, MT Insulation Payback
Teton County attic insulation, by the numbers
Teton 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. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 1.6 years at an estimated $2,123/year saved. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $2,098 a year on the heating side, $25 on cooling. By estimated insulation savings, Teton County lands in the 87th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Teton County comes in 276th by savings. Montana averages $2,182/year across the counties tracked here; Teton County comes in 3% lower.
The climate data behind this
NOAA's CHOTEAU, MT US station, 4.2 miles from Teton County, supplies the 7,845 HDD and 155 CDD this estimate runs on. That combined heating-and-cooling load ranks Teton County 452nd nationally by total degree days — the 86th percentile. One local detail the R-value alone won't tell you: Teton County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
If the attic isn't bare
If Teton 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 $310/year — payback about 7.4 years. Worth doing on the numbers alone.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $3,480 figure above as a planning number for Teton County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Teton 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.