Open Cell vs. Closed Cell Spray Foam Insulation

Whether you are building a new home or doing some energy efficiency upgrades, the right insulation is critical to the comfort of your home. Inefficient insulation can increase your heating and cooling costs by as much as 40%! Spray foam insulation is effective at air sealing and provides thermal insulation solutions to adequately insulate your home. Don’t waste precious energy! Scroll down to learn the difference between open cell and closed cell spray foam insulation from the energy efficiency pros at Solar Bear.

Open Cell and Closed Cell Spray Foam Insulation

Both open cell and closed cell spray foam are used to insulate buildings and effectively seal any cracks and gaps that allow for air loss, making buildings more comfortable and energy-efficient. While they both expand when sprayed, they have different strengths and weaknesses, and one type is not necessarily better than the other.

Let’s take a look at the differences between open and closed cell spray foam insulation.

The Cells

Spray foam insulation is described as being open or closed cell because of the differences in the small bubbles (cells) that make up the foams. They each have different physical structures that give them different thermal and acoustic performance characteristics.

Foam insulation is made up of two chemicals that when mixed, expand rapidly. During this expansion, bubbles are formed. In open cell spray foam, the bubbles partially rupture leaving behind only what is called “struts” or the point where two bubbles are touching each other. With closed cell insulation, the bubbles don’t rupture and create interconnected pockets, which in turn enhances its rigidity.

Open Cell Foam is made up of cells that have burst and are partially open. Open-cell spray foam is softer and more flexible and expands further than closed cell spray foam.

Closed Cell Foam is made up of cells that did not rupture and are completely closed, making closed cell foam much more rigid than open cell foam.


Due to the nature of closed cells, closed cell foam is much denser than open cell foam. Open cell foam generally has a density of about .5 pounds per cubic foot while closed cell foam often has a density over three times that with a density of around 1.75 pounds per cubic foot.

Due to the lighter density and porous structure of open cell spray foam, it will perform much better for sound dampening and acoustic applications. The thicker softer material of open cell spray foam reduces sound waves much more efficiently than its denser counterpart.


R-value refers to the spray foam’s heat resistance or how well they insulate. Closed cell spray foam has a higher R-value which makes it better at keeping the heat in or out of a structure. Generally closed cell spray foam has an R-value of 6.0-7.0 per square inch.

Open cell foams have an R-value of about 3.5 per inch, which can limit the usefulness of open cell insulation in places with extreme temperature conditions. But, an important thing to keep in mind is that due to its lighter density and bigger cell structure, open cell spray foam will expand 100 to 120 times its size while closed cell spray foam generally expands about 33 times its size.

So should you choose a spray foam with a higher R-value? Not necessarily. Heating and cooling losses in a home are due to not controlling or sealing air leakage properly. With Icynene spray foam, we create an air barrier to help control air leakage, and both types of foam can be beneficial to controlling air leakage and reducing energy costs.

For example, in a typical wall cavity or attic application closed cell foam installed at 2 inches would have an R-value of 14. The same insulation application done with open cell foam at 3.5 inches yields an R-value of 13. As you can see, the thermal performance of both spray foams is almost identical.


Due to the differences in the expansion rates of closed cell and open cell foam, there is a difference in cost. because of the density of closed-cell foam, it will take more material to cover the same amount of space, so it will ultimately cost more.

Benefits of Spray Foam

Closed cell foam is designed to expand to about one inch in thickness when sprayed. Multiple applications can be applied to achieve higher R-values. Open cell foam expands to about three inches of thickness, which means that one application is possible in most standard walls.

Closed Cell Spray Foam

Closed cell spray foam is the best choice for insulation when space is an issue, as it can achieve to times the R-value of open cell foam in a standard wall application. Its rigid nature also adds additional strength to the structural integrity of the building and also can act as a vapor barrier so water and moisture will be less likely to get inside the home. (The foam itself is unharmed by water or moisture.)

Open Cell Spray Foam

One of the best benefits of open cell spray foam is its rate of expansion after being applied. It can insulate hard-to-reach nooks and crannies in the home, which are hard to insulate with closed cell foam. It is also excellent for soundproofing and acoustic applications, and a single application can completely fill the area between studs.

Open cell foam is also more cost-effective and affordable than closed cell foam, but won’t insulate a home as well as a closed cell foam application, especially in areas of extreme temperature conditions.

Tampa Bay Spray Foam Insulation

While there are specific applications and projects that we would recommend one spray foam product over the other, it really comes down to what you are looking to accomplish for your specific project. Both closed cell and open cell spray foam insulation applications will seal your home, last for the lifetime of your structure, and help reduce your energy costs!

Ready to seal the air leakage in your Orlando home? Have questions? Save on energy costs and stay comfortable! Call Solar Bear today at 407-904-7585!