Walthall County, MS Insulation Payback
Walthall County attic insulation, by the numbers
DOE classifies Walthall County as climate zone 3, hot-humid — summers that stay hot and humid while winters barely register on the energy bill. Its recommended attic R-value for bare joists is R-49. Going from R-2 to the recommended R-49 costs roughly $2,820 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 3.1 years at an estimated $896/year saved. Topping up the attic pays for itself here.
Heating vs. cooling in Walthall County
Split it out and it's roughly $522 a year on the heating side, $374 on cooling. By estimated insulation savings, Walthall County lands in the 10th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Walthall County comes in 642nd by savings. Mississippi averages $1,022/year across the counties tracked here; Walthall County comes in 12% lower.
The climate data behind this
NOAA's TYLERTOWN 5ESE, MS US station, 6.4 miles from Walthall County, supplies the 1,967 HDD and 2,347 CDD this estimate runs on. By total degree days, Walthall County sits at the 7th percentile nationally. One local detail the R-value alone won't tell you: Walthall County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
The smaller top-up scenario
A shallower starting point changes the math: with R-11 already down, only the gap to R-38 needs filling, at roughly $1,620 for an estimated $121/year saved (~13.4-year payback). Call this borderline rather than a clear win.
Getting it done in Walthall County
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 Walthall County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Walthall County's R-49 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-49 is the target here specifically.