Glynn County, GA Insulation Payback
Attic insulation payback for Glynn County, GA
Glynn County, Georgia is zone 2 under DOE's climate map (Hot-Humid), which means humid heat for much of the year, with cooling running far more than heating ever does. An uninsulated attic there should be built up to R-49. For an attic around 1,000 square feet, closing the gap from R-2 to R-49 costs around $2,820 and saves an estimated $801 a year — payback in roughly 3.5 years. Worth doing on the numbers alone.
Where the savings come from
Of that, about $371/year comes from reduced heating and $430/year from reduced cooling load through the ceiling. Glynn County beats 4% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 233 counties DOE places in zone 2, Glynn County ranks 174th. Against Georgia's own average of $974/year, Glynn County runs 18% below that.
Where these numbers come from
NOAA's BRUNSWICK, GA US station, 3.1 miles from Glynn County, supplies the 1,400 HDD and 2,698 CDD this estimate runs on. Combined heating and cooling load puts Glynn County in the 3th percentile of this 3,162-county dataset. DOE also classifies Glynn County as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
The smaller top-up scenario
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 $108/year saved (~15-year payback). It is close - the payback only just fits a reasonable timeframe.
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 $2,820 figure above as a planning number for Glynn County, not a bid - contractors typically charge a $600 minimum regardless of job size.
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.