Alexander County, IL Insulation Payback
Alexander County, IL: what topping up your attic actually costs
DOE classifies Alexander County as climate zone 4, mixed-humid — real heating and real cooling seasons both, roughly balanced across the year. 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 2.5 years at an estimated $1,368/year saved. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,117/year heating, $252/year cooling. Out of every 100 US counties tracked here, Alexander County's savings potential beats roughly 43 of them. Within zone 4 specifically, it ranks 446th of 825 counties by estimated savings. Illinois averages $1,642/year across the counties tracked here; Alexander County comes in 17% lower.
The climate data behind this
Alexander County's climate figures — 4,177 heating and 1,566 cooling degree days a year — are read from CAPE GIRARDEAU MUNI AP, MO US, 12.5 miles away, NOAA's nearest 1991-2020 normals station. Combined heating and cooling load puts Alexander County in the 46th percentile of this 3,162-county dataset. Alexander 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 Alexander 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 $200/year — payback about 11.4 years. This one is a genuine toss-up, not a clear yes.
Next steps for a Alexander 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 Alexander 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.