Madison County, TN Insulation Payback
Madison County attic insulation, by the numbers
DOE classifies Madison 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. 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 2.3 years at an estimated $1,245/year saved. Topping up the attic pays for itself fast here.
Where the savings come from
Split it out and it's roughly $960 a year on the heating side, $285 on cooling. By estimated insulation savings, Madison County lands in the 34th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Madison County comes in 51st by savings. Tennessee averages $1,258/year across the counties tracked here; Madison County comes in 1% lower.
Madison County's actual weather, not a national average
Madison County's climate figures — 3,618 heating and 1,790 cooling degree days a year — are read from JACKSON EXP STN, TN US, 1.3 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Madison County 1983rd nationally by total degree days — the 37th percentile. One local detail the R-value alone won't tell you: Madison 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-38 runs about $1,620 for about $168/year saved — roughly 9.7 years to break even. Call this borderline rather than a clear win.
Quotes and materials for this job
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 Madison County's estimated $1,245/year on the line.
Where these figures come from
Madison County's R-49 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-49 is the target here specifically.