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Soy-Based Insulation


Recently we have done several posts about how to improve energy efficiency in your home. One new product that can help with “going green” is soy-based insulation.

There has been a lot of hype from different companies about this product and sometimes all that information can be confusing. Allow me to explain this product in more simple terms.

First, “soy-based” is a bit of a misnomer: just like any other blown insulation, this product is petroleum-based. The difference is that this new insulation contains up to 15% soy which replaces some of the petroleum components. Most companies that produce this blown insulation also use American-grown soybeans. The graph below indicates the breakdown of materials used in this type of blown insulation.

Soy Foam Composition

The “A Component” is the pre-insulation primer, and the “B Component” is the foam or blown insulation. When used together, these components adhere to the interior of the walls and expand to fill every little gap and keep the heat or cold out of your home.

Second, this product is healthier to use in your home because the insulation is blown in using water instead of isocyanate. This means that soy-based insulation does not “off-gas,” a term referring to the gasses produced when the isocyanate used to blow in fiberglass insulation evaporates. The isocyanate can also cause “off-gassing” as it ages because it breaks down. Soy-based insulation is sprayed in with water, which evaporates harmlessly and won’t off-gas even as it ages. And once it is dry, it stays dry because it is resistant to moisture. So kiss those mold and fungus worries goodbye!

Third, soy-based insulation won’t attract rodents: they can’t eat it. Since many of the components used in soy-based insulation are the same as that of fiberglass insulation, there is no need to worry about those pesky pests munching on it.

There are two main types of soy-based insulation. The most common, and cheaper, option is open-cell insulation. This option is cheaper because it is lighter and needs less structural support, so you have to buy less building materials. However, this option has a lower R-value. That means its heat-transfer resistance is lower. The second option is more expensive: closed-cell. Closed-cell insulation is stronger with a higher R-value. However, the closed-cell structure makes this insulation much heavier, requiring more support from the building to contain it.

You may be asking, “How does this relate to roofing?” Well, when a home is built, insulation is also placed in the ceiling of the top floor or in the attic that can affect how well your roof will perform. In our other posts we have mentioned that moisture build-up and insufficient circulation can negatively affect the roof of a home as well as the energy efficiency of the home as a whole. So really, insulation is just as important to your roof as what type of shingles you choose or what shape your deck is in!

Great big thank-you to the The Greenest Dollar for passing along this information.

“Soy Based Foam Insulation: What It Is, and Why You Should Use It.” Soy Based Foam Insulation: What It Is, and Why You Should Use It. The Greenest Dollar, 23 Feb. 2009. Web. 8 Aug. 2012. <>.

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