McMullen County, TX Insulation Payback
McMullen County, TX: what topping up your attic actually costs
McMullen County sits in IECC climate zone 2 (Hot-Humid) — long, muggy summers and mild winters, where cooling dominates the energy bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to 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 $870 a year — payback in roughly 3.2 years. The math clears comfortably within a normal ownership horizon.
Where the savings come from
The estimated savings split roughly $293/year heating, $576/year cooling. Out of every 100 US counties tracked here, McMullen County's savings potential beats roughly 8 of them. Within zone 2 specifically, it ranks 87th of 233 counties by estimated savings. Texas averages $1,035/year across the counties tracked here; McMullen County comes in 16% lower.
McMullen County's actual weather, not a national average
McMullen County's climate figures — 1,106 heating and 3,616 cooling degree days a year — are read from TILDEN 4 SSE, TX US, 3.5 miles away, NOAA's nearest 1991-2020 normals station. By total degree days, McMullen County sits at the 18th percentile nationally. McMullen County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
If McMullen 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 $117/year — payback about 13.8 years. This one is a genuine toss-up, not a clear yes.
Getting it done in McMullen County
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 McMullen 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.