St. Martin Parish, LA Insulation Payback
St. Martin Parish, LA: what topping up your attic actually costs
St. Martin Parish, Louisiana is zone 2 under DOE's climate map (Hot-Humid), which means summers that stay hot and humid while winters barely register on the energy bill. 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 3.4 years at an estimated $828/year saved. The math clears comfortably within a normal ownership horizon.
Heating vs. cooling in St. Martin Parish
The estimated savings split roughly $418/year heating, $410/year cooling. Out of every 100 US counties tracked here, St. Martin Parish's savings potential beats roughly 5 of them. Within zone 2 specifically, it ranks 141st of 233 counties by estimated savings. Louisiana averages $906/year across the counties tracked here; St. Martin Parish comes in 9% lower.
Where these numbers come from
The heating and cooling degree days behind this estimate — 1,574 HDD and 2,573 CDD (base 65°F, 1991-2020 normals) — come from JEANERETTE 5 NW, LA US, the nearest NOAA station with published normals, 12.7 miles from St. Martin Parish's center. Combined heating and cooling load puts St. Martin Parish in the 4th percentile of this 3,162-county dataset. St. Martin Parish falls in DOE's moisture regime A (humid), a detail that affects vapor-barrier recommendations more than the R-value target itself.
The smaller top-up scenario
Already have a few inches up there? Topping R-11 up to R-38 runs about $1,620 for about $111/year saved — roughly 14.5 years to break even. 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 $2,820 as a starting estimate for a St. Martin Parish 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-49 is the target here specifically.