Grant County, NM Insulation Payback
Grant County, NM: what topping up your attic actually costs
DOE classifies Grant County as climate zone 4, mixed-dry — big seasonal swings - a dry hot summer, then a real winter cold snap. 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 $1,284 a year — payback in roughly 2.7 years. That's about as fast as attic paybacks get.
Heating vs. cooling in Grant County
The estimated savings split roughly $1,144/year heating, $141/year cooling. Out of every 100 US counties tracked here, Grant County's savings potential beats roughly 37 of them. Within zone 4 specifically, it ranks 618th of 825 counties by estimated savings. New Mexico averages $1,423/year across the counties tracked here; Grant County comes in 10% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 4,278 HDD and 875 CDD (base 65°F, 1991-2020 normals) — come from CLIFF 11 SE, NM US, the nearest NOAA station with published normals, 10 miles from Grant County's center. That combined heating-and-cooling load ranks Grant County 2217th nationally by total degree days — the 30th percentile. Grant County falls in DOE's moisture regime B (dry), a detail that affects vapor-barrier recommendations more than the R-value target itself.
If the attic isn't bare
A shallower starting point changes the math: with R-11 already down, only the gap to R-49 needs filling, at roughly $2,280 for an estimated $187/year saved (~12.2-year payback). This one is a genuine toss-up, not a clear yes.
Next steps for a Grant County attic
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 Grant 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.