The Difference between Open Cell and Closed Cell Sprayfoam

insulating walls to improve home's energy efficiency

Closed cell and open cell sprayfoam are two very different products. Closed Cell foam is usually considered a more premium material because of its added advantages

In general, open cell foam is a little bit cheaper than closed cell foam however open cell foam cannot be used in all the same places as closed cell foam. When applying foam to a basement, cantilever or crawl space you should use closed cell foam most of the time because it is a great vapor barrier.

Open cell foam is growing in popularity due to its flexibility. This article states that open cell foam is better when installed in rim joists. They recommend this because the soil which the rim joists are touching (if below grade) holds moisture. Moisture naturally moves from a wet to a dry environment, causing the wood of the rim joist to hold moisture. If closed cell foam is applied, moisture can be trapped and cause the wood to rot. This article also references the fact that open cell is more flexible it can adhere to surfaces over a longer period of time when compared to closed cell foams

Always consult your local home performance company before making a decision as there are many different types of open and closed cell foams.

Below are the common differences between open and closed cell brands.

Closed Cell Foam Open Cell Foam
Hard material when cured Soft material which is same consistency of a sponge.
Hard to cut and shave Easy to shave. Can be cut with a bread knife
Adds structural integrity to surface it is applied to Does not add structural integrity
Air impermeable Air impermeable at 3 inches or more
Vapor Barrier Not a Vapor Barrier
Water impermeable Water Permeable
R-7 per inch R-3.9 per inch


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