Franklin County, ID Insulation Payback
Is attic insulation worth it in Franklin County, ID?
Franklin County, Idaho 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. 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 1.8 years at an estimated $1,944/year saved. Few home upgrades pay back that quickly.
Where the savings come from
Heating accounts for about $1,870/year of that and cooling about $74/year — Franklin County needs both. Nationally, Franklin County ranks in the 79th percentile for insulation savings potential. Compared only against its own climate zone, Franklin County places 431st out of 459. Against Idaho's own average of $1,995/year, Franklin County runs 3% below that.
The climate data behind this
NOAA's PRESTON, ID US station, 6.3 miles from Franklin County, supplies the 6,994 HDD and 461 CDD this estimate runs on. Combined heating and cooling load puts Franklin County in the 79th percentile of this 3,162-county dataset. 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.
If the attic isn't bare
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 $284/year saved (~8-year payback). Whether that is worth it depends on how long you plan to stay.
Next steps for a Franklin County attic
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 Franklin County's estimated $1,944/year on the line.
Franklin County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Franklin 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.