Spray Foam Insulation in St. Petersburg, FL

Spray foam insulation sprays on as a liquid, expands and cures in place, filling the gaps around rafters, studs, wiring and pipes. It insulates and air seals at once. In St. Petersburg, where cooling and dehumidifying run most of the year, that air seal matters as much as the R-value: every gap that lets hot, humid air into the house makes the air conditioner work harder.

Open-cell foam

Open-cell foam is soft, light and vapor-open, rated about R-3.5 to R-3.7 per inch by HomeGuide. It is the common choice for the underside of roof decks in unvented attics and for frame walls. It costs less per square foot and fills cavities completely, but it should not be used where it will get wet.

Closed-cell foam

Closed-cell foam is rigid and dense, rated about R-5 to R-7 per inch. It resists water and slows vapor, which makes it a good choice inside block walls, under raised floors on the beaches, on low-slope roof decks and in garages or metal buildings. It costs more but goes further per inch.

Where it pays off

Foam earns its cost on roof decks over attics with ducts, frame additions and Florida rooms, kneewalls and bonus rooms, garages turned into living space, and the hard-to-reach spaces in older bungalows. On a simple vented attic floor, sealing and blown-in insulation is usually cheaper, and we will tell you that.

Code and termites

The 2023 Florida energy code lists R-38 ceilings, R-13 frame walls and R-6 interior or R-4 continuous for block walls in Zone 2. The Florida Building Code also restricts foam plastic on the outside of foundation walls in very heavy termite areas and calls for a 6-inch gap above exposed earth for inspection. We keep foam where the code allows it.

Safety and curing

Foam is applied by trained installers in protective gear, with the area masked and ventilated. HomeGuide advises staying out of the house for 24 hours or more. Foam in living space is covered with drywall or another thermal barrier.