Closed-cell blocks moisture. At R-6 to R-7 per inch, closed-cell acts as its own vapor retarder. It stops Gulf humidity from reaching cooled interior surfaces, which is the main failure mode in this climate.
Open-cell costs less. Open-cell runs $0.44 to $0.65 per board foot installed versus $1.00 to $1.50 for closed-cell. For interior walls and conditioned attics, that savings is real with no meaningful performance penalty.
Closed-cell adds structural stiffness. A two-inch layer in a wall or roof deck stiffens the assembly. In hurricane country, that added rigidity reduces the risk of small cracks opening under wind load and letting driven rain in behind the cladding.
Open-cell wins on sound. Soft, flexible open-cell absorbs interior noise better than the harder closed-cell. Interior partition walls and floor assemblies between stories are where it earns its keep.
Closed-cell fits tighter spaces. It expands less and holds its shape, making it the right foam for crawl spaces, rim joists, and low-slope roof assemblies where clearance is tight and moisture is a direct concern.
Most Gulf Coast homes use both. Closed-cell goes on exterior walls, roof decks, and crawl spaces. Open-cell fills interior walls and conditioned attic floors. Using each foam where it fits best keeps costs down while managing moisture correctly.