Spink County, SD Insulation Payback
Attic insulation payback for Spink County, SD
DOE classifies Spink 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. 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 $2,304 a year in heating and cooling — a payback around 1.5 years. Hard to find a home improvement with a faster payback than this.
The breakdown behind the number
Of that, about $2,205/year comes from reduced heating and $99/year from reduced cooling load through the ceiling. Spink County beats 93% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 459 counties DOE places in zone 6, Spink County ranks 93rd. Against South Dakota's own average of $2,162/year, Spink County runs 7% above that.
Spink County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 8,245 HDD and 617 CDD (base 65°F, 1991-2020 normals) — come from REDFIELD, SD US, the nearest NOAA station with published normals, 9.9 miles from Spink County's center. Combined heating and cooling load puts Spink County in the 94th percentile of this 3,162-county dataset. DOE also classifies Spink County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
The smaller top-up scenario
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 $336/year saved (~6.8-year payback). Topping up the attic pays for itself here.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $3,480 figure above as a planning number for Spink County, not a bid - contractors typically 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.