Harnett County, NC Insulation Payback
Harnett County attic insulation, by the numbers
Harnett County, North Carolina is zone 4 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-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 3 years at an estimated $1,158/year saved. Topping up the attic pays for itself here.
The breakdown behind the number
Split it out and it's roughly $889 a year on the heating side, $269 on cooling. By estimated insulation savings, Harnett County lands in the 28th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Harnett County comes in 786th by savings. North Carolina averages $1,169/year across the counties tracked here; Harnett County comes in 1% lower.
Where these numbers come from
Harnett County's climate figures — 3,324 heating and 1,676 cooling degree days a year — are read from LILLINGTON, NC US, 3.9 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Harnett County sits at the 26th percentile nationally. One local detail the R-value alone won't tell you: Harnett County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $169/year saved — roughly 13.5 years to break even. Call this borderline rather than a clear win.
Next steps for a Harnett County attic
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 Harnett County's estimated $1,158/year on the line.
Where these figures come from
Harnett County's R-60 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-60 is the target here specifically.