Island County, WA Insulation Payback
Island County, WA: what topping up your attic actually costs
Island County sits in IECC climate zone 4 (Marine) — a mild coastal climate where the furnace and the AC both mostly stay idle. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 2.4 years at an estimated $1,448/year saved. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,444/year heating, $4/year cooling. Out of every 100 US counties tracked here, Island County's savings potential beats roughly 49 of them. Within zone 4 specifically, it ranks 277th of 825 counties by estimated savings. Washington averages $1,583/year across the counties tracked here; Island County comes in 9% lower.
Where these numbers come from
NOAA's COUPEVILLE 1 S, WA US station, 3.5 miles from Island County, supplies the 5,402 HDD and 22 CDD this estimate runs on. That combined heating-and-cooling load ranks Island County 1967th nationally by total degree days — the 38th percentile. Island County falls in DOE's moisture regime C (marine), a detail that affects vapor-barrier recommendations more than the R-value target itself.
Already have some insulation?
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 $211/year saved (~10.8-year payback). This one is a genuine toss-up, not a clear yes.
Next steps for a Island 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 Island 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.