Clark County, NV Insulation Payback
Clark County attic insulation, by the numbers
DOE classifies Clark County as climate zone 3, hot-dry — desert-dry heat for much of the year, with the attic taking the brunt of it. 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 2.7 years at an estimated $1,062/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Clark County
Split it out and it's roughly $488 a year on the heating side, $574 on cooling. By estimated insulation savings, Clark County lands in the 21th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Clark County comes in 330th by savings. Nevada averages $1,643/year across the counties tracked here; Clark County comes in 35% lower.
Clark County's actual weather, not a national average
NOAA's N LAS VEGAS, NV US station, 5.9 miles from Clark County, supplies the 1,839 HDD and 3,604 CDD this estimate runs on. Combined heating and cooling load puts Clark County in the 38th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Clark County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
The smaller top-up scenario
If Clark County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-38. That smaller top-up costs around $1,620 and saves an estimated $143/year — payback about 11.3 years. Call this borderline rather than a clear win.
Next steps for a Clark County attic
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $2,820 figure above as a planning number for Clark County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Clark 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.