Sprayfoam Insulation

When it comes time to insulate a home or commercial building, you must choose between open-cell foam and closed-cell foam. Each type of foam distinctly impacts project costs, application methods, and building performance. There are two major factors distinguishing closed-cell and open-cell foams: structure and density.

1. Cell Structure

The structure of open-cell foam consists of tiny bubbles or cells that aren’t fully encapsulated–they are broken, torn, ripped, etc. Because they’re broken, air fills the open space inside the bubble, which results in a soft, spongy material. Closed-cell foam differs in that every bubble or cell that makes up the foam is completely encapsulated and packed tightly together. The bubbles aren’t filled with air, but with a gas that aids foam expansion and insulation properties. This results in an altogether harder, stronger material than open-cell foam.

The blowing agent, which aids in forming the bubbles or cells that make up SPF’s foam structure, is usually water for open-cell and high-R-value chemicals for closed-cell.


2. Material Density

Closed-cell foam is roughly four times as dense as open-cell for insulation applications. To ascertain foam density, one cu. ft. of foam material is weighed. Open-cell tends to be roughly 0.5 lb./cu. ft. in density, whereas closed-cell ranges from 1.7 to 3.0 lb./cu. ft. in density, or even higher for certain applications. (Note: these density figures are rough averages. Every SPF product will vary based on its formulation.)

Properties of Both Open-Cell & Closed Cell Foam


Of the two types of SPF, closed-cell foam is stronger, is a better insulator, and is more resistant to the transmission of air and water vapor. Because closed-cell foam is denser, however, it requires more chemical material per unit volume than open-cell, and is therefore more expensive to install–even if comparing the cost-per-R-value.

Open-cell foam, while offering fewer overall benefits, is a superb sound-deadening material and is still a superior insulating material compared to fiberglass.