Big Horn County, MT Insulation Payback
Big Horn County, MT: what topping up your attic actually costs
Big Horn County, Montana is zone 6 under DOE's climate map (Cold), which means cold enough that heating, not cooling, is what decides the bill. 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 $2,047 a year — payback in roughly 1.7 years. That's about as fast as attic paybacks get.
Heating vs. cooling in Big Horn County
The estimated savings split roughly $1,972/year heating, $75/year cooling. Out of every 100 US counties tracked here, Big Horn County's savings potential beats roughly 84 of them. Within zone 6 specifically, it ranks 353rd of 459 counties by estimated savings. Montana averages $2,182/year across the counties tracked here; Big Horn County comes in 6% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 7,375 HDD and 468 CDD (base 65°F, 1991-2020 normals) — come from WYOLA 1 SW, MT US, the nearest NOAA station with published normals, 20.5 miles from Big Horn County's center. That combined heating-and-cooling load ranks Big Horn County 507th nationally by total degree days — the 84th percentile. Big Horn 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
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $299/year saved — roughly 7.6 years to break even. That is a solid payback as home upgrades go.
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 Big Horn County's estimated $2,047/year on the line.
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.