Boise County, ID Insulation Payback
Boise County, ID: what topping up your attic actually costs
Boise 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. 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 $2,079 a year — payback in roughly 1.7 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $2,055/year heating, $24/year cooling. Out of every 100 US counties tracked here, Boise County's savings potential beats roughly 86 of them. Within zone 6 specifically, it ranks 316th of 459 counties by estimated savings. Idaho averages $1,995/year across the counties tracked here; Boise County comes in 4% higher.
Where these numbers come from
NOAA's LOWMAN, ID US station, 8.2 miles from Boise County, supplies the 7,685 HDD and 148 CDD this estimate runs on. By total degree days, Boise County sits at the 84th percentile nationally. Boise 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
If Boise 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 $303/year — payback about 7.5 years. That is a solid payback as home upgrades go.
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 Boise 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.