St. James Parish, LA Insulation Payback
Attic insulation payback for St. James Parish, LA
St. James Parish, Louisiana 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 $813 a year — payback in roughly 3.5 years. Worth doing on the numbers alone.
Where the savings come from
Of that, about $356/year comes from reduced heating and $457/year from reduced cooling load through the ceiling. St. James Parish beats 5% of the counties in this 3,162-county dataset on estimated insulation savings. Among the 233 counties DOE places in zone 2, St. James Parish ranks 158th. Against Louisiana's own average of $906/year, St. James Parish runs 10% below that.
St. James Parish's actual weather, not a national average
The heating and cooling degree days behind this estimate — 1,342 HDD and 2,870 CDD (base 65°F, 1991-2020 normals) — come from RESERVE, LA US, the nearest NOAA station with published normals, 13 miles from St. James Parish's center. Combined heating and cooling load puts St. James Parish in the 5th percentile of this 3,162-county dataset. DOE also classifies St. James Parish as moisture regime A (humid) - ask a local contractor whether that changes the vapor-barrier approach for this job.
If the attic isn't bare
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $110/year saved — roughly 14.8 years to break even. It is close - the payback only just fits a reasonable timeframe.
Getting it done in St. James Parish
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 St. James Parish, 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.