Dewey County, SD Insulation Payback
Dewey County attic insulation, by the numbers
DOE classifies Dewey County as climate zone 6, cold — winters that dominate the energy bill, with cooling a minor factor. Its recommended attic R-value for bare joists is 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 1.6 years at an estimated $2,198/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Dewey County
Split it out and it's roughly $2,091 a year on the heating side, $107 on cooling. By estimated insulation savings, Dewey County lands in the 90th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Dewey County comes in 187th by savings. South Dakota averages $2,162/year across the counties tracked here; Dewey County comes in 2% higher.
Where these numbers come from
NOAA's TIMBER LAKE, SD US station, 22.6 miles from Dewey County, supplies the 7,821 HDD and 666 CDD this estimate runs on. That combined heating-and-cooling load ranks Dewey County 291st nationally by total degree days — the 91th percentile. One local detail the R-value alone won't tell you: Dewey County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $321/year saved — roughly 7.1 years to break even. Worth doing on the numbers alone.
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 Dewey County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Where these figures come from
Dewey 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.