Shelby County, TX Insulation Payback
Shelby County attic insulation, by the numbers
DOE classifies Shelby County as climate zone 3, hot-humid — humid heat for much of the year, with cooling running far more than heating ever does. Its recommended attic R-value for bare joists is R-49. For an attic around 1,000 square feet, closing the gap from R-2 to R-49 costs around $2,820 and saves an estimated $991 a year — payback in roughly 2.8 years. Topping up the attic pays for itself fast here.
Where the savings come from
Split it out and it's roughly $595 a year on the heating side, $396 on cooling. By estimated insulation savings, Shelby County lands in the 16th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Shelby County comes in 489th by savings. Texas averages $1,035/year across the counties tracked here; Shelby County comes in 4% lower.
The climate data behind this
The heating and cooling degree days behind this estimate — 2,241 HDD and 2,485 CDD (base 65°F, 1991-2020 normals) — come from CENTER, TX US, the nearest NOAA station with published normals, 1.7 miles from Shelby County's center. Combined heating and cooling load puts Shelby County in the 18th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Shelby County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
If Shelby County's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-38. That smaller top-up costs around $1,620 and saves an estimated $133/year — payback about 12.1 years. Call this borderline rather than a clear win.
Getting it done in Shelby County
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $2,820 as a starting estimate for a Shelby County job, not a quote. Expect at least a $600 minimum charge from most contractors.
Where these figures come from
Shelby County's R-49 target and its degree-day figures both come from named federal sources - see the methodology guide for exactly which ones. The guide to what R-value actually means explains why R-49 is the target here specifically.