Both types of spray foam insulate. But they work differently, cost differently, and make sense in different parts of your home. Here's how to know which one you need.
When homeowners hear "spray foam insulation," they usually don't know there are two different products with different properties and different best uses. Knowing the difference helps you have a smarter conversation with any contractor — and makes sure you're not paying for closed-cell when open-cell would do the job.
Open-Cell Spray Foam
Open-cell foam is softer and lighter. It expands significantly — up to 100 times its original volume — which makes it good at filling large cavities. R-value per inch is around R-3.5 to R-4. It's vapor-permeable, meaning moisture can pass through it over time. That's fine for interior applications but a liability in spaces exposed to moisture or extreme temperature swings. Open-cell works well in interior walls, attic ceilings (when the roof deck is sealed from the outside), and spaces where sound control matters.
Closed-Cell Spray Foam
Closed-cell foam is denser, harder, and has a higher R-value — around R-6 to R-7 per inch. It's a vapor barrier, which means moisture can't pass through it. It also adds structural rigidity to the surfaces it's applied to. Closed-cell makes sense for attic decks in North Texas (where summer heat and potential moisture from humidity require a stronger barrier), crawl spaces, and any exterior application. It costs more per square foot, but you need less thickness to hit the same R-value.
What Most Frisco Attics Need
For a typical Frisco home attic — sealed at the roof deck rather than the ceiling plane — closed-cell is usually the right call. The heat and humidity levels in North Texas during summer mean you want a vapor barrier and maximum R-value per inch. We'll assess your attic and tell you exactly what we'd recommend before you commit to anything.
