Kent County, DE Insulation Payback
Kent County, DE: what topping up your attic actually costs
Kent County, Delaware is zone 4 under DOE's climate map (Mixed-Humid), which means a genuine mix of cold winters and humid summers, with neither one dominating the bill. 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 $1,336/year saved. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,122/year heating, $214/year cooling. Out of every 100 US counties tracked here, Kent County's savings potential beats roughly 41 of them. Within zone 4 specifically, it ranks 512th of 825 counties by estimated savings. Delaware averages $1,363/year across the counties tracked here; Kent County comes in 2% lower.
The climate data behind this
The heating and cooling degree days behind this estimate — 4,195 HDD and 1,334 CDD (base 65°F, 1991-2020 normals) — come from DOVER, DE US, the nearest NOAA station with published normals, 3.4 miles from Kent County's center. That combined heating-and-cooling load ranks Kent County 1882nd nationally by total degree days — the 40th percentile. Kent County falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
If the attic isn't bare
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 $195/year saved (~11.7-year payback). This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
Actual quotes will vary by attic access, existing debris, and whether the job needs air sealing first. Treat the $3,480 figure above as a planning number for Kent 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-60 is the target here specifically.