Benton County, OR Insulation Payback
Benton County attic insulation, by the numbers
Benton County, Oregon is zone 4 under DOE's climate map (Marine), which means a mild coastal climate where the furnace and the AC both mostly stay idle. An uninsulated attic there should be built 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 $1,538 a year — payback in roughly 2.3 years. Topping up the attic pays for itself fast here.
The breakdown behind the number
Split it out and it's roughly $1,515 a year on the heating side, $22 on cooling. By estimated insulation savings, Benton County lands in the 55th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Benton County comes in 120th by savings. Oregon averages $1,557/year across the counties tracked here; Benton County comes in 1% lower.
The climate data behind this
NOAA's CORVALLIS WATER BUREAU, OR US station, 1.9 miles from Benton County, supplies the 5,667 HDD and 139 CDD this estimate runs on. Combined heating and cooling load puts Benton County in the 47th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Benton County sits in moisture regime C (marine), which can affect the vapor-barrier choice.
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 $224/year saved (~10.2-year payback). Call this borderline rather than a clear win.
Getting it done in Benton 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 Benton County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
Benton 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.