Charles County, MD Insulation Payback
Charles County attic insulation, by the numbers
Charles County sits in IECC climate zone 4 (Mixed-Humid) — heating load in winter and cooling load in summer, both worth taking seriously here. For a currently uninsulated attic, DOE and ENERGY STAR recommend building 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 2.7 years at an estimated $1,313/year saved. Topping up the attic pays for itself fast here.
Heating vs. cooling in Charles County
Split it out and it's roughly $1,070 a year on the heating side, $243 on cooling. By estimated insulation savings, Charles County lands in the 39th percentile nationally. Zone 4 alone covers 825 counties in this dataset, and Charles County comes in 558th by savings. Maryland averages $1,395/year across the counties tracked here; Charles County comes in 6% lower.
Charles County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 4,003 HDD and 1,512 CDD (base 65°F, 1991-2020 normals) — come from QUANTICO MCAS, VA US, the nearest NOAA station with published normals, 15.5 miles from Charles County's center. That combined heating-and-cooling load ranks Charles County 1894th nationally by total degree days — the 40th percentile. One local detail the R-value alone won't tell you: Charles County sits in moisture regime A (humid), which can affect the vapor-barrier choice.
Already have some insulation?
Already have a few inches up there? Topping R-11 up to R-49 runs about $2,280 for about $192/year saved — roughly 11.9 years to break even. Call this borderline rather than a clear win.
Getting it done in Charles County
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 Charles County's estimated $1,313/year on the line.
Where these figures come from
Charles 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.