There’s no doubt that green building is taking off in a big way (and hooray to that!). It’s getting easier, and cheaper, to build homes that are not only safe for the environment, but also safe for us.
When it comes to your home’s insulation, you’ve got some great choices to pick from. There’s regular spray foam insulation, cotton-based insulation (like those made from recycled jeans), and soy based insulation.
All have their perks and drawbacks, and I’m focusing today’s article on soy based insulation.
Important Addition: After this article originally posted on 2/23, I was contacted by James Morshead, a spray foam installer with SDI Insulation, Inc. out in California who pointed out some factual errors within the text. He generously took the time to clarify these and point me in the right direction. I have rectified those errors, and attempted to give a more balanced look at soy based foam insulation. My sincere thanks to him for separating the facts from the hype about this product!
Now, let’s jump into the fascinating world of insulation.
What Is Soy Based Insulation?
Sorry if I’m stating the obvious here, but soy based insulation is insulation that uses soy as an ingredient. It’s a spray-on foam, which means trained technicians come in with suits and tanks and spray it into the walls of your home. The insulation then expands up to 100 times its size, filling in every nook and cranny and making an incredibly tight seal
As you can probably imagine, there are many benefits to using it in your home. Let’s go.
First of all, using soy based insulation versus regular fiberglass means that you don’t have to worry about off-gassing. It’s sprayed on using water. So, it’s safe for our bodies. It also doesn’t off-gas as it ages like fiberglass might.
Contrary to some rumors out there soy based insulation does resist moisture, so you don’t have to worry about mold and fungus growth like you would with wet fiberglass insulation.
And, rodents won’t eat it, so you don’t have to worry about providing an “all you can eat” buffet for your neighborhood’s rat population.
What’s it made of?
Well, all spray foam insulation is made up of an “A Side”, which is the catalyst, and a “B Side”, which is the resin. Much like epoxy glue, the two sides are mixed together as they come out of the tank, which causes a chemical reaction and creates the “spray foam”.
Well, every brand is different, and they don’t all break down what’s in their insulation. From my research online it seems as if almost all companies use the same “A Side”. So already half of the soy based foam insulation is petroleum or chemical based.
I did uncover the material and safety data sheets (msds) put out by Urethane Soy Systems.
Urethane Soy Systems give a complete breakdown of both the “A-Side” and “B-Side” of their spray foam insulation. It’s a downloadable .pdf that you can find here.
Here’s what each side of Urethane Soy Systems soy based insulation is made from:
Polymeric Diphenylmethane Diiosocyanate 100%
Component CAS# %Composition
Polyol 68152-81-8 0-50%
Halogenated Phosphate Ester 13674-84-5 0-50%
Polyether Polyol Trade Secret 0-25%
Water 7732-18-5 0-20%
Amine Catalyst 3030-47-5 0-5%
Silicone Surfactant Trade Secret 0-5%
Soy-based insulation a green alternative to traditional fiberglass insulation.
First of all, most companies use American grown soybeans, so this helps support the more than 600,000 farmers that grow them. And considering I come from a family who’s still growing soybeans in north Louisiana, I’m pretty enthused about this part!
Important point here: many companies make it sound as if soy based foam insulation is largely made up of soybeans. This is one claim I fell for myself, and only after my “insider help” was I aware that this is part of the hype of this product.
All spray foam insulations are petroleum based. Including soy based foam insulation. The difference is that soy based foam replaces a portion of that petroleum with soy.
How much soy is actually in the finished product? Well, James at SDI Insulation said that the maximum for any spray foam is 15% soy. I dug through my resources I used, and even some I didn’t, to verify this, and could find nothing, anywhere, that actually said how much soy these companies use in their insulation.
I did find an enlightening article from SprayFoam.com. The graph below shows the breakdown in ingredients in regular spray foam insulation, and below is a quote from the article itself on the sometimes “misleading” claims of high soy content.
From the article: Jennifer Wilson of Biobased® Insulation, a soy-based SPF product, claims that its exclusive Agrol® polyol is 96% pure making it one of the purest bio-polyols on the market. Jeff Soto, Apex Foam, states that their Earth Seal Foam System offers a unique sucrose-based polyol that contributes to a B side that consists of 30% to 40% of a renewable resource, the highest renewable resource content in SPF.
Biobased® Insulation and Apex Foam are both very reputable companies with fantastic customer and third party “bio-testing” credentials and endorsements. We are proud of their efforts and do not discount any of their claims. However, one of the key objectives of this article is to educate our readers and therefore we will offer some more clarifying insight to the layman interested in using, or choosing green insulation products such as spray polyurethane foam.
Ninety six percent (96%) pure bio content – What does this claim mean? What are the “impurities”? We would suspect the answer is that the soy polyols are 96% soybean oil, modified with 4% of other (petro-chemicals) to make the oil a reactive polyol. The misconception that comes from this statement, since the word “polyol” is meaningless to most consumers, is that Biobased’s® foam is 96% Soybean based. Look at the chart above and notice that the polyol side is only 50%, or half, of the entire foam system.
There is a popular misconception that the bio-containing foams (whether soy or sugar) are more substantially green, when, in fact the final polymers are still mostly petroleum based. However, the USDA has offered the criteria that if a material is at least 9% renewable content, the claim of being “bio-based” is valid.
So while all spray foam systems have some degree of “green bio-content” in their composition, it comes down to the level of bio-based and renewable materials in their polyol mixture that distinguishes which SPF product is truly greener than the other.
Soy based insulation is just as good at insulating your home as traditional insulation. With soy based insulation you don’t have to worry about sacrificing quality in order to be more eco-friendly. You can get a high R-value in less space than bat insulation, which means in new construction this can help decrease the amount of building materials used.
Most soy based insulation companies claim their insulation will help reduce monthly energy bills by 50% or more. Soy based insulation is more expensive than regular fiberglass, but the investment will pay for itself over time.
How much more expensive? Well, I couldn’t find an exact number from the companies I researched (they all say to call for a quote…figures!).
I did find one couple who installed soy based installation in their Arts and Crafts style home, and they said the cost was three times that of regular insulation. Their blog, Humphrey House, details their insulation project and has some great pictures. They also say why they love their soybean insulation, so you should check it out.
Open Cell or Closed Cell Soy Based Insulation?
Soy based foam insulation comes in two forms: open cell and closed cell.
Open cell insulation is like broken bubbles. The walls are soft, and air gets trapped in the insulation, working like a down sleeping bag. Open cell insulation has a value of R-3.6 per inch, but is usually less expensive. It’s also very lightweight, which means you can often use less building materials when you use it.
Closed cell insulation is much harder. It’s densely packed foam, and its bubbles are not broken. This means it’s hard enough to walk on, and will even help improve your structure’s strength in high winds. Closed cell insulation is the more expensive of the two because it requires more materials to support its weight. Closed cell insulation gives an R-6.8 per inch in standard walls.
How do you know which to pick?
Well, if you live in a very cold climate, or you’re concerned with structural strength, you’ll probably want to go with closed cell.
Soy Based Insulation Resources
Check out some of these soy based insulation companies if you’re interested in using this in your home.
I must admit I was a bit floored by all the hype surrounding soy based foam insulation once my eyes were opened to it. It’s a great product, but I now realize that many companies try to make it sound much greener than it actually is.
All spray foam insulation, including soy based, is green in the sense that they can help you dramatically reduce your energy bills. And, that’s a good thing.
If you’re knowledgeable about spray foam insulation (either regular or soy-based) and you notice any errors in this post, please let me know! It’s not my intention at all to publish false or misleading information. I’ve done my best to pull information from reliable sources, but there’s a lot of mis-information out there, as I learned the hard way!
Again, my sincere thanks goes out to James Morshead with SDI Insulation, who really took time to make sure that I better understood this complicated subject.
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