Florence County, SC Insulation Payback
Is attic insulation worth it in Florence County, SC?
DOE classifies Florence County as climate zone 3, mixed-humid — a genuine mix of cold winters and humid summers, with neither one dominating the bill. Its recommended attic R-value for bare joists is 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 $979 a year in heating and cooling — a payback around 2.9 years. Few home upgrades pay back that quickly.
The breakdown behind the number
Heating accounts for about $619/year of that and cooling about $360/year — Florence County needs both. Nationally, Florence County ranks in the 15th percentile for insulation savings potential. Compared only against its own climate zone, Florence County places 513th out of 690. Against South Carolina's own average of $1,016/year, Florence County runs 4% below that.
Florence County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 2,334 HDD and 2,257 CDD (base 65°F, 1991-2020 normals) — come from FLORENCE RGNL AP, SC US, the nearest NOAA station with published normals, 10.9 miles from Florence County's center. That combined heating-and-cooling load ranks Florence County 2736th nationally by total degree days — the 13th percentile. Its moisture regime is classified humid, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
Already have some insulation?
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 $132/year saved (~12.3-year payback). Whether that is worth it depends on how long you plan to stay.
Getting it done in Florence County
Get more than one quote before committing. Attic access and any needed air sealing move the price around, and most contractors won't take a job below roughly $600 regardless of size - worth asking upfront given Florence County's estimated $979/year on the line.
Florence County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Florence County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.