St. Lucie County, FL Insulation Payback
Is attic insulation worth it in St. Lucie County, FL?
St. Lucie County, Florida 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 4.2 years at an estimated $666/year saved. That is a solid payback as home upgrades go.
The breakdown behind the number
Heating accounts for about $107/year of that and cooling about $558/year — St. Lucie County needs both. Nationally, St. Lucie County ranks in the 1th percentile for insulation savings potential. Compared only against its own climate zone, St. Lucie County places 231st out of 233. Against Florida's own average of $743/year, St. Lucie County runs 10% below that.
St. Lucie County's actual weather, not a national average
The heating and cooling degree days behind this estimate — 405 HDD and 3,502 CDD (base 65°F, 1991-2020 normals) — come from FT PIERCE, FL US, the nearest NOAA station with published normals, 7.1 miles from St. Lucie County's center. That combined heating-and-cooling load ranks St. Lucie County 3105th nationally by total degree days — the 2th percentile. Its moisture regime is classified humid, which matters for whether the attic needs a vapor retarder as part of the job — worth asking a contractor about locally.
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 $90/year saved (~18.1-year payback). Whether that is worth it depends on how long you plan to stay.
Quotes and materials for this job
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 St. Lucie County's estimated $666/year on the line.
St. Lucie County's numbers, sourced
The methodology guide lists exactly which DOE and NOAA sources feed St. Lucie County's numbers, and where the cost assumptions come from. See the DIY vs. contractor guide for whether a job this size is realistic to do yourself.