Sullivan County, TN Insulation Payback
Is attic insulation worth it in Sullivan County, TN?
DOE classifies Sullivan County as climate zone 4, mixed-humid — real heating and real cooling seasons both, roughly balanced across the year. 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 2.7 years at an estimated $1,287/year saved. Few home upgrades pay back that quickly.
Where the savings come from
Heating accounts for about $1,110/year of that and cooling about $177/year — Sullivan County needs both. Nationally, Sullivan County ranks in the 37th percentile for insulation savings potential. Compared only against its own climate zone, Sullivan County places 610th out of 825. Against Tennessee's own average of $1,258/year, Sullivan County runs 2% above that.
Sullivan County's actual weather, not a national average
NOAA's BRISTOL TRI CITY AP, TN US station, 6.3 miles from Sullivan County, supplies the 4,150 HDD and 1,105 CDD this estimate runs on. Combined heating and cooling load puts Sullivan County in the 33th percentile of this 3,162-county dataset. 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
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 $188/year saved (~12.1-year payback). Whether that is worth it depends on how long you plan to stay.
Getting it done in Sullivan County
Get more than one quote before committing. Attic access and any needed air sealing move the price around, and most contractors won't take a job below roughly $600 regardless of size - worth asking upfront given Sullivan County's estimated $1,287/year on the line.
Sullivan County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Sullivan 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.