McHenry County, IL Insulation Payback
McHenry County, IL: what topping up your attic actually costs
DOE classifies McHenry County as climate zone 5, cold — winters that dominate the energy bill, with cooling a minor factor. Its recommended attic R-value for bare joists is R-60. For an attic around 1,000 square feet, closing the gap from R-2 to R-60 costs around $3,480 and saves an estimated $1,867 a year — payback in roughly 1.9 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,743/year heating, $124/year cooling. Out of every 100 US counties tracked here, McHenry County's savings potential beats roughly 76 of them. Within zone 5 specifically, it ranks 181st of 745 counties by estimated savings. Illinois averages $1,642/year across the counties tracked here; McHenry County comes in 14% higher.
McHenry County's actual weather, not a national average
McHenry County's climate figures — 6,520 heating and 771 cooling degree days a year — are read from CRYSTAL LAKE 4NW, IL US, 5.2 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, McHenry County sits at the 76th percentile nationally. McHenry County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
If the attic isn't bare
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 $272/year saved (~8.4-year payback). This one is a genuine toss-up, not a clear yes.
Next steps for a McHenry County attic
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 McHenry County, not a bid - contractors typically charge a $600 minimum regardless of job size.
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.