Twin Falls County, ID Insulation Payback
Attic insulation payback for Twin Falls County, ID
Twin Falls County, Idaho is zone 5 under DOE's climate map (Cold), which means winters that dominate the energy bill, with cooling a minor factor. 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 $1,807 a year in heating and cooling — a payback around 1.9 years.
Hard to find a home improvement with a faster payback than this.
Where the savings come from
Of that, about $1,708/year comes from reduced heating and $99/year from reduced cooling load through the ceiling. Twin Falls County beats 73% of the counties in this 3,171-county dataset on estimated insulation savings. Among the 754 counties DOE places in zone 5, Twin Falls County ranks 281st. Against Idaho's own average of $1,995/year, Twin Falls County runs 9% below that.
Where these numbers come from
Twin Falls County's climate figures — 6,387 heating and 617 cooling degree days a year — are read from Twin Falls SUN VLY Rgnl AP, ID US, 12.8 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Twin Falls County sits at the 71st percentile nationally. DOE also classifies Twin Falls County as moisture regime B (dry) - ask a local contractor whether that changes the vapor-barrier approach for this job.
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 $264/year saved — roughly 8.7 years to break even. It is close - the payback only just fits a reasonable timeframe.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first, so treat the $3,480 figure above as a planning number for Twin Falls County, not a bid. Worth getting quotes from at least two local contractors before committing - most charge a $600 minimum regardless of job size.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.