Closed-cell spray foam (also known as 2-pound foam) has a density of about 2 pounds per cubic foot and an R-value of 6 to 6.5 per inch. Because it is a denser material, closed-cell spray foam not only provides a vapor and water barrier to a home or structure but also adds additional structural strength. Closed-cell spray foam typically costs more than open-cell spray foam.
Because the cells in closed foam have their own structure and don’t share any structure with other cells, the foam has a higher plastic content and less air. The industry standard for spray foam to qualify as “closed cell” is that greater than 90% of the cells are closed.
Advantages of Closed Cell Spray Foam
While open-cell and closed-cell foams are both polyurethane-based, the main difference between the two is that closed-cell foam is:
- Two and a half inches of closed-cell foam have a permeance of 0.8 per m. Less water/air can pass through a closed-cell foam
- Because closed-cell foam is denser, it provides added wall/structural strength. One place that open-cell would be a better fit could be an attic or ceiling, due to weight.
- Provides better insulation and water barrier
- Although it is typically more material (and therefore more costly) than open-cell spray foam, closed-cell foam is less permeable and more water-resistant. This can prevent unwanted mold/moisture in hidden places.
Although there are many advantages of having a closed spray foam insulation, the price is a drawback simply because there are more materials needed to create the denser insulation. Closed-cell foam is more expensive per “R,” so one can expect an R-10 of closed-cell to be costlier than an R-10 of open-cell. There is more plastic used in closed-cell, and the chemicals used for a blowing agent in closed-cell foam is much more expensive than the water used in open-cell foam. However, there are benefits of increased effectiveness and strength.
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