Woodford County, IL Insulation Payback
Woodford County, IL: what topping up your attic actually costs
DOE classifies Woodford County as climate zone 5, cold — a real winter that drives most of the annual energy bill here. 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 $1,709 a year — payback in roughly 2 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,538/year heating, $171/year cooling. Out of every 100 US counties tracked here, Woodford County's savings potential beats roughly 66 of them. Within zone 5 specifically, it ranks 470th of 745 counties by estimated savings. Illinois averages $1,642/year across the counties tracked here; Woodford County comes in 4% higher.
Where these numbers come from
The heating and cooling degree days behind this estimate — 5,752 HDD and 1,067 CDD (base 65°F, 1991-2020 normals) — come from CONGERVILLE 2NW, IL US, the nearest NOAA station with published normals, 11.8 miles from Woodford County's center. By total degree days, Woodford County sits at the 68th percentile nationally. Woodford 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 Woodford 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 $249/year — payback about 9.1 years. This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
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 Woodford County's estimated $1,709/year on the line.
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.