Spray Foam Insulation From Soy
Open and Closed-Cell, A Green, Sustainable Alternative to Fiberglass
Nov 18, 2008
The two questions that immediately jump to mind are, “But isn't soy food? Won't bugs and rodents eat the walls?” Usually to the first question, and no to the second. Soy, and some other biopolymers, are inert, meaning that it won't support mold growth or attract bugs or vermin.
Open-Cell and Closed-Cell Foam Insulation
This innovative green building material is available in both forms. Which type is used depends on several factors.
- Open-cell foam should only be used for interior applications because it provides no structural support. It's more cost-effective with respect to R-value than closed-cell foams.
- Closed-cell foam may be used on exterior applications. It offers low vapor penetration because of its dense cell structure. When applied sufficiently thick, it may be used as a vapor retarder (but not a vapor barrier).
What Makes Soy Insulation so Energy-Efficient and Effective?
Basically, the way it's applied and how it cures. As a spray foam, it goes on as a liquid (water-blown, chemical-free) so the coverage is highly efficient. Immediately, it begins to solidify and expand up to 100 times its original volume.
As it expands, it's forced into all empty spaces. Because of this it provides a much more air-tight envelope than traditional forms of insulation material such as fiberglass or rockwool batts. Once it's in, it's there for the long run, since it doesn't break down over time.
It adheres readily to all surfaces to which spray foam is commonly applied, including drywall and both wood and steel studs.
It's More Expensive than Some Other Insulation Materials
So why invest in it rather than fiberglass? Because it saves money in the long run. As an example, suppose a new home construction is being financed. Assume the additional cost of the soy increases the monthly mortgage payment by $20.
But because of the energy efficiency of this type of spray foam, thermal gain and loss are minimized and the central air conditioning and heating system doesn't have to work as hard. It's conceivable that the electricity and natural gas utility bills may actually be reduced by $70.
That's a net saving of $50! Nothing to sneeze at, especially considering that the home's resale value is also higher.
A Very Impressive R-Value
When applied in a standard wall cavity of 3.5 inches (8.89 centimeters) it has an R-Value of 13 to 18, depending on the particular formulation. And because of the way it's applied, it also minimizes moisture issues.
Soy has a fire rating of Class 1. What does this mean? Building materials with a Class 1 fire rating will char but will not sustain a flame.
It's Ideal for Insulated Concrete Form Construction (ICF)
Insulated concrete form construction is a hot, new green building practice that's gathering a head of steam. Soy is an ideal insulation to be used. ICF utilizes a modular foam block with an empty cavity inside.
The wall is assembled with the blocks, braced, and has concrete poured into the voids. The concrete cures and viola! An instant wall with insulation on both sides!
