Open Cell Vs Closed Cell Foam Insulation

Open Cell Vs Closed Cell Foam

It seems quite a few readers have questions about the difference between open cell and closed cell foam insulation.Understanding the difference between open cell and closed cell foam insulation is the most important step in determining which product is best for your next insulation project.

Foam Insulation Porosity – Vapor Barrier Issue

Open Cell Foam Insulation is a porous material that can allow air and moisture to penetrate the insulation. Closed Cell Foam Insulation is non-porous with all of the voids closed to each other which makes it difficult for water vapor and air to pass through it. The porosity of the two materials is the biggest difference and most important issue. If your insulation application needs a vapor barrier then you MUST select closed cell foam insulation.

Foam Insulation Density – Cost & Strength Issue

The other major difference between open cell and closed cell foam insulation is the density of the in-place foam.  Open cell foams typically weigh about 0.5 lbs per cubic foot while closed cell foams are about 3 lbs per cubic foot. Ultimately this is why closed cell foams are stronger and denser allowing them to carry heavier loads. This is also one of the reasons that closed cell foam is quite a bit more expensive compared to open cell foam.

Insulating Value – R Values Per Inch

The final issue when discussing the differences between open cell and closed cell foam insulation is the insulating value or R value per inch of insulation. Open cell foam insulation typically has average R values of about 3.5 per inch while closed cell foam insulation has average R values of about 6.5. So you can see closed cell foam insulation can be almost twice the insulating values per inch.

Photo Credit: Elizabeth Buie

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