Rock County, WI Insulation Payback
Rock County, WI: what topping up your attic actually costs
Rock County, Wisconsin is zone 6 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. 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 $1,972/year saved. That's about as fast as attic paybacks get.
Heating vs. cooling in Rock County
The estimated savings split roughly $1,858/year heating, $114/year cooling. Out of every 100 US counties tracked here, Rock County's savings potential beats roughly 81 of them. Within zone 6 specifically, it ranks 416th of 459 counties by estimated savings. Wisconsin averages $2,200/year across the counties tracked here; Rock County comes in 10% lower.
The climate data behind this
The heating and cooling degree days behind this estimate — 6,947 HDD and 710 CDD (base 65°F, 1991-2020 normals) — come from AFTON - JANESVILLE WWTP, WI US, the nearest NOAA station with published normals, 2.3 miles from Rock County's center. That combined heating-and-cooling load ranks Rock County 589th nationally by total degree days — the 81th percentile. Rock County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
If Rock 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 $288/year — payback about 7.9 years. That is a solid payback as home upgrades go.
Getting it done in Rock County
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 Rock County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-60 is the target here specifically.