Tuolumne County, CA Insulation Payback
Tuolumne County attic insulation, by the numbers
Tuolumne County, California is zone 4 under DOE's climate map (Mixed-Dry), which means big seasonal swings - a dry hot summer, then a real winter cold snap. An uninsulated attic there should be built up to R-60. Going from R-2 to the recommended R-60 costs roughly $3,480 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 2.6 years at an estimated $1,351/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Tuolumne County
Split it out and it's roughly $1,220 a year on the heating side, $130 on cooling. By estimated insulation savings, Tuolumne County lands in the 42th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Tuolumne County comes in 481st by savings. California averages $1,056/year across the counties tracked here; Tuolumne County comes in 28% higher.
Where these numbers come from
NOAA's CHERRY VALLEY DAM, CA US station, 4.2 miles from Tuolumne County, supplies the 4,564 HDD and 812 CDD this estimate runs on. That combined heating-and-cooling load ranks Tuolumne County 2000th nationally by total degree days — the 37th percentile. One local detail the R-value alone won't tell you: Tuolumne County sits in moisture regime B (dry), which can affect the vapor-barrier choice.
The smaller top-up scenario
A shallower starting point changes the math: with R-11 already down, only the gap to R-49 needs filling, at roughly $2,280 for an estimated $197/year saved (~11.6-year payback). 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 Tuolumne County's estimated $1,351/year on the line.
Where these figures come from
Tuolumne County's R-60 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-60 is the target here specifically.