Platte County, WY Insulation Payback
Is attic insulation worth it in Platte County, WY?
DOE classifies Platte County as climate zone 5, cold — a real winter that drives most of the annual energy bill here. 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 $1,795 a year in heating and cooling — a payback around 1.9 years. Few home upgrades pay back that quickly.
Where the savings come from
Heating accounts for about $1,704/year of that and cooling about $91/year — Platte County needs both. Nationally, Platte County ranks in the 72th percentile for insulation savings potential. Compared only against its own climate zone, Platte County places 308th out of 745. Against Wyoming's own average of $2,161/year, Platte County runs 17% below that.
Where these numbers come from
Platte County's climate figures — 6,373 heating and 565 cooling degree days a year — are read from WHEATLAND 4 N, WY US, 1.5 miles away, NOAA's nearest 1991-2020 normals station. Combined heating and cooling load puts Platte County in the 70th percentile of this 3,162-county dataset. Its moisture regime is classified dry, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $262/year saved — roughly 8.7 years to break even. Whether that is worth it depends on how long you plan to stay.
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 Platte County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Platte County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Platte County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.