Mineral County, MT Insulation Payback
Mineral County, MT: what topping up your attic actually costs
Mineral 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 $1,854 a year — payback in roughly 1.9 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,790/year heating, $64/year cooling. Out of every 100 US counties tracked here, Mineral County's savings potential beats roughly 75 of them. Within zone 6 specifically, it ranks 449th of 459 counties by estimated savings. Montana averages $2,182/year across the counties tracked here; Mineral County comes in 15% lower.
Where these numbers come from
Mineral County's climate figures — 6,694 heating and 400 cooling degree days a year — are read from SUPERIOR, MT US, 10.1 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Mineral County 848th nationally by total degree days — the 73th percentile. Mineral County falls in DOE's moisture regime B (dry), a detail that affects vapor-barrier recommendations more than the R-value target itself.
If the attic isn't bare
If Mineral 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 $270/year — payback about 8.4 years. This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $3,480 as a starting estimate for a Mineral County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-60 is the target here specifically.