Jefferson County, MS Insulation Payback
Attic insulation payback for Jefferson County, MS
DOE classifies Jefferson County as climate zone 3, hot-humid — long, muggy summers and mild winters, where cooling dominates the energy bill. Its recommended attic R-value for bare joists is R-49. For an attic around 1,000 square feet, closing the gap from R-2 to R-49 costs around $2,820 and saves an estimated $968 a year — payback in roughly 2.9 years. Hard to find a home improvement with a faster payback than this.
Where the savings come from
Of that, about $574/year comes from reduced heating and $394/year from reduced cooling load through the ceiling. Jefferson County beats 14% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 690 counties DOE places in zone 3, Jefferson County ranks 544th. Against Mississippi's own average of $1,022/year, Jefferson County runs 5% below that.
The climate data behind this
The heating and cooling degree days behind this estimate — 2,163 HDD and 2,470 CDD (base 65°F, 1991-2020 normals) — come from PORT GIBSON 1 NE, MS US, the nearest NOAA station with published normals, 17.9 miles from Jefferson County's center. Combined heating and cooling load puts Jefferson County in the 15th percentile of this 3,162-county dataset. DOE also classifies Jefferson County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
If the attic isn't bare
If Jefferson County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-38. That smaller top-up costs around $1,620 and saves an estimated $130/year — payback about 12.4 years. It is close - the payback only just fits a reasonable timeframe.
Next steps for a Jefferson County attic
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $2,820 as a starting estimate for a Jefferson County job, not a quote. Expect at least a $600 minimum charge from most contractors.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.