When you think about insulation, your first thought might be warmth, not moisture. But in Louisville’s mixed-humid climate, managing moisture vapor is just as important as managing heat. That’s where spray foam insulation shines. Understanding the differences between open-cell and closed-cell spray foam can help you make the right choice for your home’s comfort, energy efficiency, and durability.
Let’s take a closer look at how these two types of spray foam compare, where each one works best, and how Louisville Insulation helps you choose the right fit.
Key Differences Between Open-Cell and Closed-Cell Spray Foam
While both open-cell and closed-cell spray foam expand to seal gaps and stop air leaks, they’re built very differently.
- Open-cell spray foam is softer and more flexible, with a sponge-like texture that makes it great for soundproofing and filling irregular cavities. It’s excellent at creating an air seal, but it’s also vapor-permeable, which means moisture vapor can pass through it. That doesn’t make it a bad product—just one that needs to be used in the right spots where vapor control isn’t as critical.
- Closed-cell spray foam, on the other hand, is dense, rigid, and built to resist moisture vapor. Its structure blocks both air and vapor, offering not only high insulating power but also added structural strength to walls and surfaces. It’s a smart choice for areas where high humidity or vapor intrusion is a concern, like crawl spaces, basements, rim joists, and exterior walls.
Why Vapor Resistance Matters
In the Louisville region, moisture is a year-round challenge. And while you might not see water pooling in your insulation, moisture vapor can still sneak in and wreak havoc behind the scenes.
If insulation gets damp, its effectiveness drops. Those tiny air pockets that help resist heat flow get compromised, reducing the material’s R-value. Moisture also invites mold, musty smells, and air quality issues, especially in closed-up areas like attics or crawl spaces. Over time, unchecked moisture vapor can even cause wood rot, rust, and long-term structural damage.
That’s why choosing the right spray foam matters—not just for energy savings, but for the health and longevity of your home.
Where Each Type of Spray Foam Works Best
Closed-cell spray foam
Ideal for areas that face greater moisture exposure or that benefit from added strength. Think crawl spaces, rim joists, and exterior walls—any place where you want insulation that both seals and protects. Its dense structure helps keep moisture vapor out, while also delivering top-notch thermal performance.
Open-cell spray foam
Better suited to drier, interior parts of the home. It works well in interior walls where sound control is a priority, as well as in attics and vaulted ceilings, as long as moisture is properly managed and the space is well ventilated.
Ultimately, it’s not just about picking one or the other—it’s about choosing the right material for the right location.
Trust the Foam Gnomes to Get It Right
At Louisville Insulation, we don’t just show up and spray foam wherever there’s a gap. Our team of Foam Gnomes takes the time to evaluate how your home handles airflow and vapor movement so we can recommend the right insulation strategy for each space.
We’re local, we know Louisville homes, and we understand what this climate throws at them. Whether you need the moisture-managing strength of closed-cell foam or the flexible, sound-dampening performance of open-cell, we’ve got the know-how to make sure your home stays comfortable, energy efficient, and protected year-round.
