A Homeowner's Guide To Closed And Open Cell Foam Insulation

Posted on: 4 May 2020

Spray foam insulation comes in two major varieties — open-cell or closed-cell. Both have their benefits, so it is important to understand how these products differ so you can choose the proper type of insulation for your project.

Cell Types

Both types of foam are comprised of "cells," but open foam cells aren't fully enclosed so air passes between them. Closed-cell foam cells are completely enclosed, so there is no airflow within the insulation once it is installed. Open-cell insulation is more flexible, so it works well in hard to reach places or odd-shaped nooks, whereas closed-cell is more rigid and provides a sturdier structure.

Insulation Density

Closed-cell insulation is about three times as dense as open-cell insulation, which means a sturdier product per inch of thickness. Although no spray foam can stand alone, closed-cell foam is dense enough to be used in between flimsier materials because it can help add strength to an existing structure.

Insulating Value

Closed-cell foam tends to provide more insulation value per inch of thickness, in part due to its increased density and in part because air doesn't flow as readily through the closed cells. Of course, insulation values can vary widely, with some open-cell products outperforming certain closed-cell products. Always check the R-value of any insulation you are considering. The higher the R-value, the more insulating ability.

Expansion Space

Open-cell foam products need space to expand in order to reach their full insulating potential. Generally, this means they are best suited for larger open areas, such as in an attic or between your floorboards. Closed-cell insulation requires much less space to provide the same or greater amounts of insulation. Closed-cell foam is perfect for those tight areas, such as around window and door frames or in the narrow spaces of your walls.

Noise Buffering

If noise is a concern, then open-cell may actually be the better choice. The greater thickness helps reduce noise better than many closed-cell products, while the open cells absorb noise without allowing it to pass through. Closed-cell insulation does provide some noise buffering, but generally not quite as well as open-cell foam.

Fire Prevention

Closed-cell foam comes in varieties that contain fire retardants, which can increase the safety of your home or building. This makes it an especially good insulation choice in workshops, near gas appliances, in the kitchen, or in other areas where fire danger is greater.

Contact an insulation service to learn more about closed-cell foam insulation.