Custer County, ID Insulation Payback
Custer County, ID: what topping up your attic actually costs
Custer County, Idaho is zone 6 under DOE's climate map (Cold), which means a real winter that drives most of the annual energy bill here. An uninsulated attic there should be built up to 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 $2,134 a year in heating and cooling — a payback around 1.6 years. That's about as fast as attic paybacks get.
Heating vs. cooling in Custer County
The estimated savings split roughly $2,084/year heating, $50/year cooling. Out of every 100 US counties tracked here, Custer County's savings potential beats roughly 88 of them. Within zone 6 specifically, it ranks 257th of 459 counties by estimated savings. Idaho averages $1,995/year across the counties tracked here; Custer County comes in 7% higher.
Custer County's actual weather, not a national average
NOAA's CHALLIS AP, ID US station, 17.3 miles from Custer County, supplies the 7,795 HDD and 312 CDD this estimate runs on. By total degree days, Custer County sits at the 87th percentile nationally. Custer County falls in DOE's moisture regime B (dry), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
A shallower starting point changes the math: with R-11 already down, only the gap to R-49 needs filling, at roughly $2,280 for an estimated $311/year saved (~7.3-year payback). That is a solid payback as home upgrades go.
Next steps for a Custer County attic
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 Custer County, not a bid - contractors typically charge a $600 minimum regardless of job size.
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.