Clark County, ID Insulation Payback
Is attic insulation worth it in Clark County, ID?
Clark County sits in IECC climate zone 6 (Cold) — cold enough that heating, not cooling, is what decides the bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building 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 1.5 years at an estimated $2,276/year saved. Few home upgrades pay back that quickly.
Heating vs. cooling in Clark County
Heating accounts for about $2,243/year of that and cooling about $33/year — Clark County needs both. Nationally, Clark County ranks in the 93th percentile for insulation savings potential. Compared only against its own climate zone, Clark County places 114th out of 459. Against Idaho's own average of $1,995/year, Clark County runs 14% above that.
Where these numbers come from
Clark County's climate figures — 8,387 heating and 208 cooling degree days a year — are read from SMALL 6N, ID US, 2.7 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Clark County sits at the 92th percentile nationally. Its moisture regime is classified dry, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
The smaller top-up scenario
If Clark 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 $332/year — payback about 6.9 years. The math clears comfortably within a normal ownership horizon.
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 Clark County's estimated $2,276/year on the line.
Clark County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Clark County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.