Is There an Eco-friendly Spray Foam Insulation?

spray foam insulation

(image: dunktanktechnician)

Are plant based spray foam insulations environmentally friendly? You may be surprised by the answer.


In my quest for an environmentally-friendly building insulation, I came across this short video of my friend and the former publisher of Mother Earth News, Bryan Welch. He and Danny Lipford of Today’s Homeowner talk about cotton denim batt insulation and soy-based spray foam.

I had never heard of soy-based spray foam, so I began to look into it.

Spray foam insulation benefits

  • In general, spray foam insulation has many appealing benefits, when installed correctly:
  • In new construction, it is sprayed on the inside of exterior walls. It completely seals up the joints where air can leak into and out of your house, wasting heating and cooling energy.
  • In a retrofit, insulation is sprayed into wall cavities by removing a small piece of siding, which gets patched afterwards.
  • For small touch-up jobs around the house, spray foam comes in aerosol cans for homeowners.
  • Spray foam insulation has an R-value of 5-6 per inch, higher than that of traditional insulation.
  • It gets into hard-to-reach places around plumbing, wiring, windows, and angles.
  • Spray foam protects against moisture and water damage, reducing the likelihood of mold and mildew.
  • As all insulations, it reduces heating and cooling bills, saving money and natural resources, and has good acoustic qualities.

It’s main drawback, though, is that it’s toxic.

Not so ‘green’

Spray Polyurethane Foam (SPF) is made of a blend of petroleum-based chemicals that are mixed as they are being sprayed. Isocyanates, including MDI (methylene diphenyl diisocyanate), are toxic and regulated by the EPA. Exposure can cause severe respiratory and skin problems, and prolonged exposure can cause death.

These volatile organic compounds (VOCs) are emitted during the spray process, endangering installers. Workers need to wear respirators and be covered in protective clothing, since the chemicals can also be absorbed through the skin. Homeowners using canned foam are even more endangered, if they do not understand the dangers and how to protect themselves.

sprayfoam insulation

(image: dunktanktechnician)

Toxicity issues

Supposedly, when the foam hardens, the chemicals become inert, making them ‘safe’. But tests have shown that if the chemicals are not mixed in the right proportion or conditions are not prime for application, the foam may never harden, leaving the final product to off-gas.

Furthermore, if some of the insulation needs to be removed for repairs or remodeling, dust from the project can be as dangerous as when the insulation was applied. In the event of a fire, the foam releases its locked up VOCs out back out into the atmosphere.

The EPA and insulation industry are aware of the problems of SPF and are testing isocyanate-free alternatives.

Are bio-alternatives eco-friendly?

You can probably see why soy-based spray foam insulation is so appealing to me! Bio-based spray insulation sounds like heaven, doesn’t it? Plants are non-toxic, renewable, and recyclable, and the great insulating properties of spray foam are not lost.

The oil of soybeans, castor beans, and cashew shells is extracted from the plant to replace the isocyanates and MDI.

But! It only replaces roughly 15%, leaving 85% petroleum based material.

The ‘eco’ in eco-friendly spray foam insulation usually means it is sprayed with water, not fluorocarbons that damage the ozone layer. It doesn’t mean it’s completely plant based.

Not so good news

I wish I could report that I found the perfect spray foam insulation. I’m pretty disappointed to see such a large percentage of petroleum in a so-called bio-based product.

I am so sensitive to petroleum based products (WD-40 is not my friend!) that even a soy-based spray foam would probably make me wheeze.

Onward in my search for the perfect, environmentally friendly and effective insulation!

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