Smith County, TX Insulation Payback
Smith County, TX: what topping up your attic actually costs
DOE classifies Smith County as climate zone 3, hot-humid — long, muggy summers and mild winters, where cooling dominates 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 $949 a year in heating and cooling — a payback around 3 years. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $535/year heating, $414/year cooling. Out of every 100 US counties tracked here, Smith County's savings potential beats roughly 13 of them. Within zone 3 specifically, it ranks 577th of 690 counties by estimated savings. Texas averages $1,035/year across the counties tracked here; Smith County comes in 8% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 2,017 HDD and 2,597 CDD (base 65°F, 1991-2020 normals) — come from TYLER, TX US, the nearest NOAA station with published normals, 5 miles from Smith County's center. Combined heating and cooling load puts Smith County in the 14th percentile of this 3,162-county dataset. Smith County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
Already have some insulation?
If Smith 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 $128/year — payback about 12.7 years. This one is a genuine toss-up, not a clear yes.
Next steps for a Smith County attic
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $2,820 figure above as a planning number for Smith County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Nothing here is a guess
Every figure on this page traces to DOE/IECC climate zones and NOAA degree-day normals, documented in the methodology guide. The guide to what R-value actually means explains why R-49 is the target here specifically.