Blanco County, TX Insulation Payback
Blanco County attic insulation, by the numbers
DOE classifies Blanco County as climate zone 3, hot-humid — summers that stay hot and humid while winters barely register on the energy bill. Its recommended attic R-value for bare joists is R-49. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-49 runs an estimated $2,820, and saves about $943 a year in heating and cooling — a payback around 3 years. Topping up the attic pays for itself fast here.
Heating vs. cooling in Blanco County
Split it out and it's roughly $515 a year on the heating side, $429 on cooling. By estimated insulation savings, Blanco County lands in the 13th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and Blanco County comes in 587th by savings. Texas averages $1,035/year across the counties tracked here; Blanco County comes in 9% lower.
Blanco County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 1,940 HDD and 2,689 CDD (base 65°F, 1991-2020 normals) — come from JOHNSON CITY 2N, TX US, the nearest NOAA station with published normals, 2.4 miles from Blanco County's center. Combined heating and cooling load puts Blanco County in the 15th percentile of this 3,162-county dataset. One local detail the R-value alone won't tell you: Blanco County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
If Blanco 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 $127/year — payback about 12.8 years. Call this borderline rather than a clear win.
Quotes and materials for this job
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 Blanco County's estimated $943/year on the line.
Where these figures come from
Blanco 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.