Clay County, MS Insulation Payback
Clay County, MS: what topping up your attic actually costs
Clay County, Mississippi is zone 3 under DOE's climate map (Mixed-Humid), which means real heating and real cooling seasons both, roughly balanced across the year. An uninsulated attic there should be built 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 $1,068 a year in heating and cooling — a payback around 2.6 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $716/year heating, $352/year cooling. Out of every 100 US counties tracked here, Clay County's savings potential beats roughly 22 of them. Within zone 3 specifically, it ranks 312th of 690 counties by estimated savings. Mississippi averages $1,022/year across the counties tracked here; Clay County comes in 5% higher.
The climate data behind this
The heating and cooling degree days behind this estimate — 2,699 HDD and 2,207 CDD (base 65°F, 1991-2020 normals) — come from STATE UNIV, MS US, the nearest NOAA station with published normals, 13.2 miles from Clay County's center. That combined heating-and-cooling load ranks Clay County 2440th nationally by total degree days — the 23th percentile. Clay 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
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $144/year saved — roughly 11.3 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 Clay 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.