Fayette County, IL Insulation Payback
Fayette County, IL: what topping up your attic actually costs
Fayette County sits in IECC climate zone 4 (Mixed-Humid) — real heating and real cooling seasons both, roughly balanced across the year. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to 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 $1,554 a year in heating and cooling — a payback around 2.2 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,349/year heating, $205/year cooling. Out of every 100 US counties tracked here, Fayette County's savings potential beats roughly 57 of them. Within zone 4 specifically, it ranks 92nd of 825 counties by estimated savings. Illinois averages $1,642/year across the counties tracked here; Fayette County comes in 5% lower.
The climate data behind this
Fayette County's climate figures — 5,046 heating and 1,274 cooling degree days a year — are read from BROWNSTOWN 4 SW, IL US, 4.5 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Fayette County 1317th nationally by total degree days — the 58th percentile. Fayette County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
Already have some insulation?
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 $227/year saved (~10.1-year payback). This one is a genuine toss-up, not a clear yes.
Next steps for a Fayette County attic
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 Fayette County's estimated $1,554/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.