While spray foam insulation may appear to look the same, it’s offered in both open cell and closed cell. Which material your insulation contractor opts for can have a significant impact on your attic’s R-value and the overall energy efficiency of your home. Here’s what you need to know.
Density: One of the biggest differences between open cell foam insulation and closed cell foam insulation is their densities. Closed cell is heavy and inflexible, where open cell spray foam insulation is more flexible and forgiving. The type of application should be taken into consideration when deciding which type of spray foam to use. For example, in a home with new electrical, open cell tends to work better because it is easier to manipulate. However, in a shed, the closed cell’s rigorous properties work well because it can better withstand impact.
Expansion Rate: Another way in which the two materials vary is how much they expand when they are applied. Open cell insulation has a much greater expansion rate, which is helpful when trying to fill all surface crevices in attics, rim joists, and crawl spaces. Closed cell has a much lower rate which works well in other scenarios.
Sound Reduction: If one of the major goals of the spray foam insulation project is to reduce noise, open cell spray foam insulation will do a better job. This is because it expands at a higher rate and can fill in all fissures that may be allowing noise to enter a space.
Moisture Absorption: Closed cell spray foam insulation’s rigid consistency allows it to have a lower moisture permeability rating than open cell spray foam insulation. Closed cell spray foam insulation works well in attics, most notably when applied to the underside of the roof deck, as it will prevent moisture from being transmitted.
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R-Value: R-value measures the ability of a material to insulate and combat the flow of heat. The higher the R-value, the more effective the material is. Because of its density, closed cell foam insulation has a higher R-value than open cell foam insulation.
Price: Both types of insulation utilize a blowing agent to fashion the cells inside it. Water is the blowing agent for open cell insulation, whereas closed cell spray foam insulation uses chemicals in addition to water, adding to its expense. The density of closed cell spray foam insulation also means that more of the material must be used than if the same space was being insulated with open cell spray foam insulation.