Grafton County, NH Insulation Payback
Grafton County attic insulation, by the numbers
DOE classifies Grafton County as climate zone 6, cold — winters that dominate the energy bill, with cooling a minor factor. Its recommended attic R-value for bare joists is R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $2,152 a year in heating and cooling — a payback around 1.6 years. Topping up the attic pays for itself fast here.
Where the savings come from
Split it out and it's roughly $2,098 a year on the heating side, $53 on cooling. By estimated insulation savings, Grafton County lands in the 88th percentile nationally. Zone 6 alone covers 459 counties in this dataset, and Grafton County comes in 237th by savings. New Hampshire averages $2,071/year across the counties tracked here; Grafton County comes in 4% higher.
Where these numbers come from
NOAA's WENTWORTH, NH US station, 5.5 miles from Grafton County, supplies the 7,847 HDD and 333 CDD this estimate runs on. By total degree days, Grafton County sits at the 88th percentile nationally. One local detail the R-value alone won't tell you: Grafton County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
The smaller top-up scenario
If Grafton County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $314/year — payback about 7.3 years. Worth doing on the numbers alone.
Next steps for a Grafton 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 Grafton County's estimated $2,152/year on the line.
Where these figures come from
Grafton 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.