Spartanburg County, SC Insulation Payback
Spartanburg County, SC: what topping up your attic actually costs
Spartanburg County sits in IECC climate zone 3 (Mixed-Humid) — real heating and real cooling seasons both, roughly balanced across the year. 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 2.6 years at an estimated $1,065/year saved. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $800/year heating, $265/year cooling. Out of every 100 US counties tracked here, Spartanburg County's savings potential beats roughly 22 of them. Within zone 3 specifically, it ranks 322nd of 690 counties by estimated savings. South Carolina averages $1,016/year across the counties tracked here; Spartanburg County comes in 5% higher.
Where these numbers come from
The heating and cooling degree days behind this estimate — 3,015 HDD and 1,664 CDD (base 65°F, 1991-2020 normals) — come from SPARTANBURG 3 SSE, SC US, the nearest NOAA station with published normals, 4.7 miles from Spartanburg County's center. That combined heating-and-cooling load ranks Spartanburg County 2654th nationally by total degree days — the 16th percentile. Spartanburg County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $143/year saved — roughly 11.3 years to break even. This one is a genuine toss-up, not a clear yes.
Next steps for a Spartanburg 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 Spartanburg County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-49 is the target here specifically.