Johnson County, IN Insulation Payback
Is attic insulation worth it in Johnson County, IN?
Johnson County, Indiana is zone 5 under DOE's climate map (Cold), which means winters that dominate the energy bill, with cooling a minor factor. An uninsulated attic there should be built up to 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 2.1 years at an estimated $1,682/year saved. Few home upgrades pay back that quickly.
The breakdown behind the number
Heating accounts for about $1,538/year of that and cooling about $144/year — Johnson County needs both. Nationally, Johnson County ranks in the 65th percentile for insulation savings potential. Compared only against its own climate zone, Johnson County places 512th out of 745. Against Indiana's own average of $1,634/year, Johnson County runs 3% above that.
Where these numbers come from
The heating and cooling degree days behind this estimate — 5,752 HDD and 897 CDD (base 65°F, 1991-2020 normals) — come from FRANKLIN WWTP, IN US, the nearest NOAA station with published normals, 3.4 miles from Johnson County's center. By total degree days, Johnson County sits at the 65th percentile nationally. Its moisture regime is classified humid, 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 $245/year saved — roughly 9.3 years to break even. Whether that is worth it depends on how long you plan to stay.
Next steps for a Johnson County attic
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 Johnson County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Johnson County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Johnson 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.