Most Cape Coral and Southwest Florida homes are built from concrete masonry units (CMU) — concrete block. Block is tough and storm-resistant, but it soaks up heat all day and radiates it inside well into the evening.
The "thermal battery" problem
Uninsulated block has very little resistance to heat. On a 90-degree day your walls absorb solar heat for hours, then keep releasing it inside long after sunset — forcing your AC to run late into the night. Insulating the walls breaks the cycle.
Ways to insulate block walls
- Interior furring + rigid foam board — foam board on furring strips inside the block, then drywalled over.
- Interior spray foam — closed-cell foam adds high R-value and an air/moisture seal in one step.
- Injection foam — foam injected into the hollow block cores for whole-wall coverage without demolition.
- During renovation — if walls are already open, it's the ideal time to insulate.
Because Florida is hot and humid, moisture control is critical — the right assembly keeps humidity from being trapped in the wall.
Is it worth it?
For block homes with high afternoon and evening cooling bills, wall insulation flattens those temperature swings and takes load off your AC. Paired with a well-insulated attic, it's one of the biggest comfort upgrades available.
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Related: Highest R-value guide · What is batt insulation?