An R-12 Wall is an R-12 Wall No Matter the Material

Originally published by: Fine Homebuilding — July 23, 2019

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There is more than one way to build an energy efficient wall assembly using spray foam as a key component. Even though spray foam is a fairly new product in the construction scene, it is clear that changes to the energy code combined with a sustained desire for continuous insulation and air tight wall construction will allow spray foam to quickly become a common application. There are a variety of ways to install and integrate spray foam into a building assembly. For additional insight, please review the approach taken by energy-efficient building expert Bruce Harley from Vermont.

Bruce Harley

Spray foam can be a great material, but understanding its use is often hindered by overeager installers who emphasize the magic rather than the real properties of the products. Too often, I hear from clients that “my dealer said that I only need 2 in. to 4 in. of foam in my walls because it performs just like r-40 fiberglass and prevents any possible moisture problems.” It’s just not true. An r-12 wall is an r-12 wall, no matter what the material is. Cutting air leakage saves energy, but it doesn’t make up for a low r-value. For best performance, I use spray foam in a variety of ways when designing the shell of a home.

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For additional information and commentary on the effects of insulation, please read the following articles:

Posted on July 31, 2019 in Building Science, Energy Efficiency