Rankin County, MS Insulation Payback
Rankin County, MS: what topping up your attic actually costs
Rankin County sits in IECC climate zone 3 (Hot-Humid) — summers that stay hot and humid while winters barely register on the energy bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-49. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-49 runs an estimated $2,820, and saves about $972 a year in heating and cooling — a payback around 2.9 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $590/year heating, $383/year cooling. Out of every 100 US counties tracked here, Rankin County's savings potential beats roughly 14 of them. Within zone 3 specifically, it ranks 534th of 690 counties by estimated savings. Mississippi averages $1,022/year across the counties tracked here; Rankin County comes in 5% lower.
The climate data behind this
NOAA's JACKSON INTL AP, MS US station, 8.5 miles from Rankin County, supplies the 2,222 HDD and 2,402 CDD this estimate runs on. By total degree days, Rankin County sits at the 14th percentile nationally. Rankin 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
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $131/year saved — roughly 12.4 years to break even. This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $2,820 figure above as a planning number for Rankin 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-49 is the target here specifically.