Clark County, WA Insulation Payback
Clark County attic insulation, by the numbers
Clark County sits in IECC climate zone 4 (Marine) — temperate and damp most of the year, with neither heating nor cooling asking for much. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to 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 $1,444 a year — payback in roughly 2.4 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,418 a year on the heating side, $26 on cooling. By estimated insulation savings, Clark County lands in the 49th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Clark County comes in 285th by savings. Washington averages $1,583/year across the counties tracked here; Clark County comes in 9% lower.
Clark County's actual weather, not a national average
NOAA's BATTLE GROUND, WA US station, 2.1 miles from Clark County, supplies the 5,303 HDD and 164 CDD this estimate runs on. That combined heating-and-cooling load ranks Clark County 1931st nationally by total degree days — the 39th percentile. One local detail the R-value alone won't tell you: Clark County sits in moisture regime C (marine), which can affect the vapor-barrier choice.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $211/year saved — roughly 10.8 years to break even. Call this borderline rather than a clear win.
Next steps for a Clark 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 Clark County's estimated $1,444/year on the line.
Where these figures come from
Clark 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.