Baltimore city, MD Insulation Payback
Baltimore city, MD: what topping up your attic actually costs
Baltimore city, Maryland is zone 4 under DOE's climate map (Mixed-Humid), which means real heating and real cooling seasons both, roughly balanced across the year. An uninsulated attic there should be built 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 $1,312 a year in heating and cooling — a payback around 2.7 years. That's about as fast as attic paybacks get.
The breakdown behind the number
The estimated savings split roughly $1,032/year heating, $281/year cooling. Out of every 100 US counties tracked here, Baltimore city's savings potential beats roughly 39 of them. Within zone 4 specifically, it ranks 560th of 825 counties by estimated savings. Maryland averages $1,395/year across the counties tracked here; Baltimore city comes in 6% lower.
The climate data behind this
The heating and cooling degree days behind this estimate — 3,858 HDD and 1,749 CDD (base 65°F, 1991-2020 normals) — come from MD SCI CTR BALTIMORE, MD US, the nearest NOAA station with published normals, 1.3 miles from Baltimore city's center. Combined heating and cooling load puts Baltimore city in the 42th percentile of this 3,162-county dataset. Baltimore city 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
If Baltimore city's attic already has 3-4 inches of old insulation (about R-11) rather than bare joists, the recommended target drops to R-49. That smaller top-up costs around $2,280 and saves an estimated $191/year — payback about 11.9 years. This one is a genuine toss-up, not a clear yes.
Quotes and materials for this job
Real bids depend on how easy the attic is to reach and whether old insulation needs removing first, so treat $3,480 as a starting estimate for a Baltimore city job, not a quote. Expect at least a $600 minimum charge from most contractors.
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.