Spray Foam Insulation in Tallahassee, FL

Spray foam insulation is a liquid that expands as it is sprayed, fills the cavity it lands in and cures into a solid layer that both insulates and blocks air. In Tallahassee, where Wikipedia's climate table lists average July humidity of about 80% and 58.81 inches of yearly rain, blocking air also means blocking a lot of water vapor from getting into the house. Who needs it? Homes with ducts in a hot attic, crawl spaces that smell musty, rooms over garages or porches, additions, and metal buildings. A quick way to tell: if one room is always hotter than the rest, or your AC runs most of a summer afternoon, there is usually an air leak worth finding.

Closed cell vs open cell

Open-cell foam cures soft and spongy and expands a lot, so a thin spray fills an irregular cavity. HomeGuide rates it at R-3.5 to R-3.7 per inch. It is a good air barrier and dampens sound, and it costs less. Water vapor can pass through it, so the design has to account for that. Closed-cell foam cures hard and dense, at R-5 to R-7 per inch in HomeGuide's figures. At normal thickness it slows vapor, sheds water rather than soaking it up, and adds some stiffness to what it is sprayed on.

In North Florida, open-cell is the common choice under a roof deck when an attic becomes an unvented, conditioned space, and in interior or above-grade walls. Closed-cell fits places that can get damp: crawl space walls, the underside of raised floors near the coast, rim boards, and the steel in metal buildings. Plenty of houses use both.

Unvented attics: bringing the ducts inside

Many Tallahassee homes have the air handler and ductwork in a vented attic that can run far hotter than the outdoor air on a sunny afternoon. Every leak in that ductwork dumps cooled air into a hot space. Spraying foam on the underside of the roof deck and sealing the gable and soffit vents turns the attic into a semi-conditioned space, so the ducts sit in air near indoor temperature. This changes how the roof assembly handles moisture, so it has to be planned, not improvised. We look at roof age, any leaks, combustion appliances in the attic and how the space will be kept dry before we recommend it.

Code levels and the right thickness

Leon County is in IECC Climate Zone 2A. The Insulation Institute's summary of the 2023 Florida Building Code, Energy Conservation lists R-38 ceilings and R-13 wood-frame walls in Zone 2. Foam under a roof deck is often designed to a performance path rather than a straight R-38, so the thickness on your quote will be tied to the approach chosen for your home. We write both the thickness and the R-value on the quote so you can compare it with other bids.

Where foam is the wrong choice

Foam does not fix a leak. If the roof, a window or a pipe is wetting the framing, it needs repair first, or foam will hide the damage. Old knob-and-tube wiring should be checked by an electrician before anything covers it. And on a wide attic floor with room to work, blown-in insulation over good air sealing is often the lower-cost way to reach R-38. Florida's building code also limits foam plastic on the outside face of foundation walls in very heavy termite areas and keeps a six-inch inspection gap between soil and siding, so we keep foam out of those zones.

Prep, spraying and getting back in

The spraying goes quickly; the prep takes time. We cover floors and belongings, mask windows, vents and fixtures, and set up ventilation. HomeGuide recommends leaving the house for at least 24 hours while foam cures. Once cured, foam does not settle or sag, so the thickness we leave is the thickness you keep.

Tell us which spaces you are thinking about and what you have noticed. We will look and send a written foam plan with a price. Get a free estimate