St. Francois County, MO Insulation Payback
St. Francois County, MO: what topping up your attic actually costs
DOE classifies St. Francois County as climate zone 4, mixed-humid — heating load in winter and cooling load in summer, both worth taking seriously here. Its recommended attic R-value for bare joists is 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 $1,432 a year in heating and cooling — a payback around 2.4 years. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,217/year heating, $215/year cooling. Out of every 100 US counties tracked here, St. Francois County's savings potential beats roughly 48 of them. Within zone 4 specifically, it ranks 312th of 825 counties by estimated savings. Missouri averages $1,534/year across the counties tracked here; St. Francois County comes in 7% lower.
St. Francois County's actual weather, not a national average
St. Francois County's climate figures — 4,551 heating and 1,341 cooling degree days a year — are read from FARMINGTON, MO US, 3.7 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, St. Francois County sits at the 49th percentile nationally. St. Francois 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
If St. Francois 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 $209/year — payback about 10.9 years. This one is a genuine toss-up, not a clear yes.
Getting it done in St. Francois County
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 St. Francois 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.