Washington County, CO Insulation Payback
Attic insulation payback for Washington County, CO
DOE classifies Washington County as climate zone 5, cold — cold enough that heating, not cooling, is what decides the bill. Its recommended attic R-value for bare joists is 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 $1,793 a year — payback in roughly 1.9 years. Hard to find a home improvement with a faster payback than this.
The breakdown behind the number
Of that, about $1,662/year comes from reduced heating and $131/year from reduced cooling load through the ceiling. Washington County beats 72% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 745 counties DOE places in zone 5, Washington County ranks 311th. Against Colorado's own average of $2,043/year, Washington County runs 12% below that.
The climate data behind this
The heating and cooling degree days behind this estimate — 6,216 HDD and 815 CDD (base 65°F, 1991-2020 normals) — come from AKRON 4 E, CO US, the nearest NOAA station with published normals, 13.6 miles from Washington County's center. Combined heating and cooling load puts Washington County in the 72th percentile of this 3,162-county dataset. DOE also classifies Washington County as moisture regime B (dry) - ask a local contractor whether that changes the vapor-barrier approach for this job.
The smaller top-up scenario
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 $262/year saved (~8.7-year payback). It is close - the payback only just fits a reasonable timeframe.
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 Washington County, not a bid - contractors typically charge a $600 minimum regardless of job size.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.