Sumner County, TN Insulation Payback
Is attic insulation worth it in Sumner County, TN?
DOE classifies Sumner 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. 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 $1,355 a year — payback in roughly 2.6 years. Few home upgrades pay back that quickly.
Heating vs. cooling in Sumner County
Heating accounts for about $1,148/year of that and cooling about $207/year — Sumner County needs both. Nationally, Sumner County ranks in the 43th percentile for insulation savings potential. Compared only against its own climate zone, Sumner County places 475th out of 825. Against Tennessee's own average of $1,258/year, Sumner County runs 8% above that.
Where these numbers come from
The heating and cooling degree days behind this estimate — 4,293 HDD and 1,289 CDD (base 65°F, 1991-2020 normals) — come from BETHPAGE 1 S, TN US, the nearest NOAA station with published normals, 7.5 miles from Sumner County's center. By total degree days, Sumner County sits at the 42th 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.
Already have some insulation?
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 $198/year saved (~11.5-year payback). Whether that is worth it depends on how long you plan to stay.
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 Sumner County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Sumner County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed Sumner 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.