Yes — and the effect in Florida is dramatic. Proper attic insulation creates a thermal barrier between your scorching attic (which can hit 160°F in summer) and your living space. Without it, that heat radiates down through your ceiling all day and night.
R-38 blown-in fiberglass, the Florida Building Code minimum, is roughly 10–12 inches of material. It dramatically slows heat transfer compared to the R-11 to R-19 insulation common in older Florida homes.
In practice, Florida homeowners who upgrade from R-11 to R-38 typically see: indoor temperatures drop 2–5°F, AC runtime decrease by 20–30%, and energy bills fall by 15–25% during summer months.
Air sealing combined with insulation amplifies the effect even further. Unsealed gaps around light fixtures, plumbing penetrations, and attic hatches allow hot air to bypass even good insulation. Florida Attics always recommends addressing air sealing before or alongside insulation upgrades for maximum results.