Carroll County, NH Insulation Payback
Carroll County, NH: what topping up your attic actually costs
DOE classifies Carroll County as climate zone 6, cold — cold enough that heating, not cooling, is what decides the bill. Its recommended attic R-value for bare joists is R-60. For an attic around 1,000 square feet, closing the gap from R-2 to R-60 costs around $3,480 and saves an estimated $2,230 a year — payback in roughly 1.6 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $2,195/year heating, $34/year cooling. Out of every 100 US counties tracked here, Carroll County's savings potential beats roughly 91 of them. Within zone 6 specifically, it ranks 162nd of 459 counties by estimated savings. New Hampshire averages $2,071/year across the counties tracked here; Carroll County comes in 8% higher.
The climate data behind this
Carroll County's climate figures — 8,211 heating and 214 cooling degree days a year — are read from TAMWORTH 4, NH US, 3.2 miles away, NOAA's nearest 1991-2020 normals station. That combined heating-and-cooling load ranks Carroll County 313th nationally by total degree days — the 90th percentile. Carroll 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
If Carroll 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 $325/year — payback about 7 years. That is a solid payback as home upgrades go.
Getting it done in Carroll County
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $3,480 figure above as a planning number for Carroll County, not a bid - contractors typically charge a $600 minimum regardless of job size.
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-60 is the target here specifically.