Glacier County, MT Insulation Payback
Is attic insulation worth it in Glacier County, MT?
DOE classifies Glacier County as climate zone 6, cold — winters that dominate the energy bill, with cooling a minor factor. 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 1.4 years at an estimated $2,539/year saved. Few home upgrades pay back that quickly.
The breakdown behind the number
Heating accounts for about $2,531/year of that and cooling about $8/year — Glacier County needs both. Nationally, Glacier County ranks in the 98th percentile for insulation savings potential. Compared only against its own climate zone, Glacier County places 7th out of 459. Against Montana's own average of $2,182/year, Glacier County runs 16% above that.
Glacier County's actual weather, not a national average
Glacier County's climate figures — 9,466 heating and 50 cooling degree days a year — are read from ST MARY, MT US, 20.1 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, Glacier County sits at the 97th percentile nationally. 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 $370/year saved — roughly 6.2 years to break even. The math clears comfortably within a normal ownership horizon.
Getting it done in Glacier 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 Glacier County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Glacier County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Glacier 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.