What is Closed-Cell Foam Insulation and How Does it Compare to Open-Cell Foam?

Closed-cell foam is made up of cells that, as the name suggests, are completely closed. The cells are pressed together, so that air and moisture cannot enter the foam. Because of this, closed-cell foam is much stiffer and more stable than open-cell foam.

Aerosol foam

is called a closed cell or an open cell because of the structure of the material itself and the composition of the cellular structure.

The difference between open-cell and closed-cell insulation lies in the small cells, which are similar to bubbles. Open-cell spray foam insulation bubbles are open, allowing air and water to pass through and providing a smoother overall structure. On the other hand, the bubbles in closed-cell aerosol foam are closed, blocking the movement of air and water and making it more rigid. Both can provide an air seal, but only with an applied thickness of two inches for closed cells and three inches for open cells.

Open-cell foam is cheaper than closed-cell foam since it expands faster and much more compared to closed cells. Therefore, less open-cell foam is needed to cover the area you want to isolate, which means a lower cost at the end of the day. That said, once you look at the differences between open-cell foam and closed-cell foam, you'll better understand which one best fits the needs of your project.

Spray foam insulation

is one of the most popular forms of insulation today.

The thickness of the spray foam really depends on where you apply it and what you're trying to achieve. Closed-cell foam is typically three to four times heavier than open-cell foam, and typically ranges from 1.75 to 2.2 pounds per cubic foot. Open-cell and closed-cell aerosol foams share many of the same qualities that provide tremendous benefits and value to the consumer. Therefore, if there are applications where it is better or easier to apply insulation to the outside of the building, closed-cell foam would be the best solution for these situations.

Homes installed with icynene spray foam typically have an ACH (air changes per hour) of less than 3, which is substantially lower than what most typical building codes require. Closed-cell insulation foam, denser than open-cell aerosol foam and other types of conventional insulating materials, has the highest R value. If your building needs to be sprayed from the outside or has the opportunity to be exposed to continuous water, then you will need to use closed-cell foam since it does not allow water to pass through, can reject bulk water and is approved by FEMA. Because closed-cell insulation foam has a higher R-value compared to open-cell aerosol foam and many other types of insulation, such as fiberglass or cellulose, it is a superior thermal insulator.