Loudoun County, VA Insulation Payback
Loudoun County, VA: what topping up your attic actually costs
Loudoun County sits in IECC climate zone 4 (Mixed-Humid) — a genuine mix of cold winters and humid summers, with neither one dominating the bill. For a currently uninsulated attic, DOE and ENERGY STAR recommend building up to R-60. Topping up a typical 1,000-square-foot attic from bare joists (R-2) to R-60 runs an estimated $3,480, and saves about $1,490 a year in heating and cooling — a payback around 2.3 years. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,321/year heating, $169/year cooling. Out of every 100 US counties tracked here, Loudoun County's savings potential beats roughly 52 of them. Within zone 4 specifically, it ranks 189th of 825 counties by estimated savings. Virginia averages $1,342/year across the counties tracked here; Loudoun County comes in 11% higher.
Where these numbers come from
NOAA's PURCELLVILLE, VA US station, 5.7 miles from Loudoun County, supplies the 4,942 HDD and 1,050 CDD this estimate runs on. That combined heating-and-cooling load ranks Loudoun County 1533rd nationally by total degree days — the 52th percentile. Loudoun 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?
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $217/year saved — roughly 10.5 years to break even. This one is a genuine toss-up, not a clear yes.
Next steps for a Loudoun County attic
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 Loudoun 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.