We get the same call every hurricane season, usually about a week after the water recedes. Someone pulled out their wall insulation, and it’s soaked through, mouldy, and has to come out entirely. The house next door had the same flood, and their insulation dried out fine, still in the wall. Often, the difference comes down to which type of insulation was used during construction, and it’s the same reason we push closed-cell foam for almost anything in Florida that has a real chance of getting wet.
Closed Cell vs. Open Cell Foam: What Makes the Difference?
Open- and closed-cell foam look similar enough from a distance that most people never think about the difference until a storm makes it obvious. Open-cell foam is built from interconnected pores, so water and air pass straight through it, which is fine for a couch cushion and a disaster for anything near a flood plain. Closed-cell foam has sealed cells that greatly limit water absorption and moisture penetration. That single structural fact is doing almost all the work in everything below.
It’s also why closed-cell foam tends to be denser and stiffer. Sealed cells packed tightly together just hold their shape better under pressure than a soft, interconnected structure does, which matters for anything getting stepped on, sat on, or loaded with weight over years. For applications carrying significant loads, the compressive strength and density of the foam matter. That’s why marine support products use materials selected to handle the expected load without excessive deformation. f. Closed-cell holds the shape it was cut to.
How Closed Cell Foam Handles Florida Heat, Humidity, and Water
Heat is the other half of the Florida problem, and it’s less dramatic than a flood, but it’s constant. A roof or a wall here absorbs sun for ten, eleven hours a day for most of the year. Sealed air pockets inside closed-cell foam slow that heat transfer down more effectively than an open structure can, which is the actual reason it ends up inside walk-in coolers, HVAC ducting, and roofing systems around the state rather than something softer and cheaper.
Where Closed Cell Foam Is Used Across Florida
Here’s where it actually plays out on a job site. EPS is closed-cell, and that’s the entire reason it survives in insulation work here without turning into a mold problem five years in. Dock floats and boat stands only work because the foam under them isn’t slowly absorbing water and getting heavier every season, which is why XLPE shows up constantly around marinas. Underground, geofoam sitting against Florida’s water table for decades needs to stay exactly the size it started as, not slowly swell and lose the structural performance an engineer designed around. Swimming pool fill has the same requirement: sitting wet against pool water for the life of the installation.
The flooding piece is the one that actually costs people money, not just performance on paper. Flooded insulation decisions depend on the specific material, contamination, duration of exposure, drying conditions, and applicable remediation requirements. Closed-cell foam in that same flood can often just get wiped down and left exactly where it is. If your project sits anywhere near a flood zone, and most of this state qualifies one way or another, that’s not a minor spec detail. It’s the difference between a repair bill and a phone call.
Not every application needs the same density, and we’d rather ask a few questions than guess. Call 727-447-0085 any day of the week, or use the contact page, and tell us what you’re actually building. We’ll point you to the right foam for that specific job, not whatever happens to be easiest to cut that afternoon.