King County, TX Insulation Payback
King County attic insulation, by the numbers
King County sits in IECC climate zone 3 (Hot-Dry) — desert-dry heat for much of the year, with the attic taking the brunt of it. 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 $1,184 a year — payback in roughly 2.4 years. Topping up the attic pays for itself fast here.
Heating vs. cooling in King County
Split it out and it's roughly $803 a year on the heating side, $381 on cooling. By estimated insulation savings, King County lands in the 30th percentile nationally. Zone 3 alone covers 690 counties in this dataset, and King County comes in 116th by savings. Texas averages $1,035/year across the counties tracked here; King County comes in 14% higher.
The climate data behind this
The heating and cooling degree days behind this estimate — 3,026 HDD and 2,391 CDD (base 65°F, 1991-2020 normals) — come from GUTHRIE, TX US, the nearest NOAA station with published normals, 5.3 miles from King County's center. By total degree days, King County sits at the 38th percentile nationally. One local detail the R-value alone won't tell you: King County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $159/year saved — roughly 10.2 years to break even. Call this borderline rather than a clear win.
Next steps for a King 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 King County, not a bid - contractors typically charge a $600 minimum regardless of job size.
Where these figures come from
King 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.