Clackamas County, OR Insulation Payback
Clackamas County, OR: what topping up your attic actually costs
DOE classifies Clackamas County as climate zone 4, marine — a mild coastal climate where the furnace and the AC both mostly stay idle. Its recommended attic R-value for bare joists is R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $1,536 a year in heating and cooling — a payback around 2.3 years. That's about as fast as attic paybacks get.
Where the savings come from
The estimated savings split roughly $1,504/year heating, $32/year cooling. Out of every 100 US counties tracked here, Clackamas County's savings potential beats roughly 55 of them. Within zone 4 specifically, it ranks 124th of 825 counties by estimated savings. Oregon averages $1,557/year across the counties tracked here; Clackamas County comes in 1% lower.
The climate data behind this
Clackamas County's climate figures — 5,625 heating and 201 cooling degree days a year — are read from THREE LYNX, OR US, 6.7 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Clackamas County sits at the 48th percentile nationally. Clackamas County falls in DOE's moisture regime C (marine), a detail that affects vapor-barrier recommendations more than the R-value target itself.
If the attic isn't bare
If Clackamas County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $224/year — payback about 10.2 years. This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $3,480 as a starting estimate for a Clackamas County job, not a quote. Expect at least a $600 minimum charge from most contractors.
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.