Yamhill County, OR Insulation Payback

Yamhill County, OR: what topping up your attic actually costs

DOE classifies Yamhill County as climate zone 4, marine — temperate and damp most of the year, with neither heating nor cooling asking for much. Its recommended attic R-value for bare joists is 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 2.8 years at an estimated $1,256/year saved. That's about as fast as attic paybacks get.

The breakdown behind the number

The estimated savings split roughly $1,197/year heating, $59/year cooling. Out of every 100 US counties tracked here, Yamhill County's savings potential beats roughly 35 of them. Within zone 4 specifically, it ranks 671st of 825 counties by estimated savings. Oregon averages $1,557/year across the counties tracked here; Yamhill County comes in 19% lower.

The climate data behind this

NOAA's MC MINNVILLE, OR US station, 7.7 miles from Yamhill County, supplies the 4,477 HDD and 366 CDD this estimate runs on. By total degree days, Yamhill County sits at the 21th percentile nationally. Yamhill 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 $183/year saved (~12.4-year payback). This one is a genuine toss-up, not a clear yes.

Quotes and materials for this job

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 Yamhill 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.