Marshall County, OK Insulation Payback
Attic insulation payback for Marshall County, OK
Marshall County, Oklahoma is zone 3 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-49. Going from R-2 to the recommended R-49 costs roughly $2,820 installed for a typical attic (about 1,000 sq ft), and pays for itself in about 2.4 years at an estimated $1,167/year saved. Hard to find a home improvement with a faster payback than this.
The breakdown behind the number
Of that, about $801/year comes from reduced heating and $366/year from reduced cooling load through the ceiling. Marshall County beats 29% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 690 counties DOE places in zone 3, Marshall County ranks 132nd. Against Oklahoma's own average of $1,260/year, Marshall County runs 7% below that.
Marshall County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 3,019 HDD and 2,298 CDD (base 65°F, 1991-2020 normals) — come from MADILL, OK US, the nearest NOAA station with published normals, 4.5 miles from Marshall County's center. Combined heating and cooling load puts Marshall County in the 35th percentile of this 3,162-county dataset. DOE also classifies Marshall County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
Already have some insulation?
A shallower starting point changes the math: with R-11 already down, only the gap to R-38 needs filling, at roughly $1,620 for an estimated $157/year saved (~10.3-year payback). It is close - the payback only just fits a reasonable timeframe.
Getting it done in Marshall 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 Marshall County's estimated $1,167/year on the line.
More on how this was built
Nothing here is a guess: the methodology guide names the DOE climate map and NOAA station data behind every number on this page. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.