Horry County, SC Insulation Payback
Attic insulation payback for Horry County, SC
Horry County sits in IECC climate zone 3 (Hot-Humid) — humid heat for much of the year, with cooling running far more than heating ever does. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to 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 years at an estimated $948/year saved. Hard to find a home improvement with a faster payback than this.
The breakdown behind the number
Of that, about $607/year comes from reduced heating and $341/year from reduced cooling load through the ceiling. Horry County beats 13% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 690 counties DOE places in zone 3, Horry County ranks 580th. Against South Carolina's own average of $1,016/year, Horry County runs 7% below that.
The climate data behind this
NOAA's CONWAY, SC US station, 7 miles from Horry County, supplies the 2,288 HDD and 2,141 CDD this estimate runs on. That combined heating-and-cooling load ranks Horry County 2869th nationally by total degree days — the 9th percentile. DOE also classifies Horry County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
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 $128/year saved (~12.7-year payback). It is close - the payback only just fits a reasonable timeframe.
Next steps for a Horry 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 Horry 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.