What is the Difference between Open-cell and Closed-cell Polyurethane Foams?

This may be one of the most important pages on the website if your interest is in spray foam insulation. When it comes time to put the foam product in your home or commercial building structure, you must identify whether you will use .05 lb./cu. ft., open cell foam, or 2.0 lb./cu. ft. closed cell foam. This makes a big difference in cost, application methods, and performance.

With the open-cell vs. closed-cell issue, there are two major factors to understand and consider. The first is the nature of the foam. It is either open-cell foam, where the tiny cells of the foam are not completely closed. They are broken and air fills all of the “open” space inside the material. This makes the foam weaker or softer feeling than closed-cell foam.

​

Closed-cell foam differs in that all of its tiny foam cells are closed and packed together. They are filled with a gas that helps the foam rise and expand and become a greater insulator. These cells can be formulated to obtain many characteristics, the most common being size and density.

Density is measured by weighing one solid cubic foot of foam material. Open cell foams typically weigh in at 0.4 to 0.5 lb./cu. ft. Closed cell foam for insulation applications ranges in density from 1.7 lb./cu. ft. to 2.0 lb./cu. ft. Roofing applications typically use a 2.8 to 3.0+ lb./cu. ft. to support traffic and loads better. The higher the density of the foam, the heavier, or stronger it becomes. Some polyurethane foams are molded into decorative interior molding and painted or stained for a simulated wood effect. These “higher density” foams are typically in the 30 lb./cu. ft. to 40 lb./cu. ft. density range.

Open-cell foam is a polyurethane-based foam, that uses different Catalysts and Blowing agents, Typically water and not a manufactured chemical blowing agent. This chemistry is different from that in closed-cell foam which uses chemical blowing agents in them. all spray foams are polyurethane-based foam. Open-cell foam normally has an R value from 2.8 to 4.1 depending on the manufacturer's blend. Closed cell Foam has an R-value from 6.5 to 7.5 depending on the manufacturer's blend and will give you a class 1 vapor retarder at 1-inch open cell typically not give you a vapor retarder.

​

closed-cell foam has a higher R-value per inch than open-cell foam, meaning it needs less roof and wall cavity space to meet the state or local building code requirements so in a 2x4 wall you can typically get to code. closed-cell spray foam can add up to 300% racing structural strength to your building Open-cell foam is softer and does not give any structural strength.  The spray applications are the same for open and closed Foam the technique might differ slightly. closed-cell foam is recommended to be installed on top of a concrete surface and in areas like dirt crawl spaces or areas like walk-in coolers high humidity areas or areas with large temperature swings.

​

closed cell spray foam insulation expands about 30% larger than its liquid applied coat and within 30 seconds has expanded adding structural strength and sealing out air infiltration helping to keep your temperature more stable and constant thus helping reduce your heating and air conditioning monthly cost. many times you can also downsize the HVAC unit size saving you in the upfront cost.