Roof deck: conditioned attic. Foam is sprayed on the underside of the roof deck, bringing the attic inside your home's thermal and air barrier. The space stays near your living temperature, your ductwork stops baking, and humid outside air cannot enter through soffit and ridge vents.
Attic floor: vented attic. Foam is applied across the attic floor, separating the conditioned living space from the unconditioned attic above. It costs less, but the attic stays hot, the vents stay open, and any ductwork up there keeps sweating and working against you all summer.
Closed-cell is standard for the roof deck here. At R-6 to R-7 per inch, closed-cell acts as its own vapor retarder. On the Gulf Coast, that moisture resistance is not optional for an exterior assembly. Open-cell is vapor-open and will let humid outdoor air reach cooled surfaces inside the attic.
Open-cell is a workable option for the floor. When the attic stays vented and the goal is to stop radiant heat from driving into ceilings below, open-cell on the attic floor gets the job done at lower cost. The attic itself stays humid, but the conditioned living space is protected.
Ductwork is the deciding factor for most Lake Charles homes. If your HVAC ducts run through the attic, foaming the floor leaves them sitting in 130-degree air all summer. A roof deck application brings the ducts inside the conditioned envelope and reduces the load on your cooling system. If ducts run in a conditioned space or a crawl space, foaming the floor becomes more practical.
Existing insulation typically comes out before the job starts. Old blown-in or batt insulation on the attic floor is removed before closed-cell goes on the roof deck. If you are foaming the floor instead, existing batts may stay or go depending on their condition. We assess both before quoting.