Mellette County, SD Insulation Payback
Mellette County attic insulation, by the numbers
Mellette County, South Dakota is zone 5 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. 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 $1,955/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Mellette County
Split it out and it's roughly $1,808 a year on the heating side, $147 on cooling. By estimated insulation savings, Mellette County lands in the 80th percentile nationally. Zone 5 alone covers 745 counties in this dataset, and Mellette County comes in 89th by savings. South Dakota averages $2,162/year across the counties tracked here; Mellette County comes in 10% lower.
Where these numbers come from
Mellette County's climate figures — 6,763 heating and 916 cooling degree days a year — are read from CEDAR BUTTE, SD US, 13.2 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Mellette County sits at the 82th percentile nationally. One local detail the R-value alone won't tell you: Mellette County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
The smaller top-up scenario
If Mellette 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 $285/year — payback about 8 years. Worth doing on the numbers alone.
Next steps for a Mellette 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 Mellette County's estimated $1,955/year on the line.
Where these figures come from
Mellette County's R-60 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-60 is the target here specifically.