Understanding the Basics of Spray Foam Insulation
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This article will outline some of the basics about spray foam insulation and describe some of the most common terms in the spray foam insulation industry.
The Two Different Types of Spray Foam
While different types of spray foams share a similar application, open-cell and closed-cell foams have distinct properties and are suited for different purposes.
Open-Cell Foam
Open-cell foam uses less material during manufacturing, resulting in a lower R-value (insulating ability). When applied, it expands to about three inches thick, providing an R-value of roughly 3.5 to 3.6 per inch. This means a single application offers an R-value of 10 to 11. Open-cell foam is a cost-effective choice for milder climates and is excellent for soundproofing.
Closed-Cell Foam
In contrast, closed-cell foam is much denser, offering a higher R-value of approximately 6.5 to 7 per inch. This superior R-value provides greater thermal protection, making it a powerful insulator. It expands to about one inch thick, and you can apply multiple layers to achieve much higher R-values. If your priority is maintaining warmth or coolness in extreme temperatures, closed-cell foam is the ideal product.
What is R-Value?
R-value measures how well something resists heat flow. A higher R-value means better heat resistance and, therefore, better insulation. Think of it this way: a Styrofoam cooler has a higher R-value than a paper bag. This resistance works both ways, similar to a Thermos, keeping both warm and cool air where you want it.
Insulation is rated by its R-value per inch, indicating how effective each inch of thickness is. The higher this rating, the more efficient the insulation. Spray foam boasts some of the highest R-values per inch in the industry.
What are Board Feet?
Board feet are similar to square feet but include thickness. One board foot is equal to an area of one foot by one foot, at a thickness of one inch. So, a 200 board foot kit would cover 200 square feet at one inch thick. It's crucial to use board feet when planning any spray foam project because you can apply multiple one-inch layers to achieve your desired total R-value.
How does a 2-Component Spray Foam Insulation Kit Work?
Spray foam insulation kits come with two separate tanks containing the primary ingredients—isocyanate and polyol resin—that create the foam. Similar to a household epoxy, these two chemicals remain inactive until they're mixed. Fortunately, there's no need for manual mixing sticks here! Once you connect the hoses, the tanks automatically combine their contents. As these ingredients flow into the hose, they react, transforming from two liquids into spray foam.
Is Spray Foam Insulation Safe?
Once cured, spray foam is essentially inert and much safer than fiberglass or cellulose, which can irritate the skin and respiratory system. The main safety considerations for spray foam are during its application, where proper safety gear is essential.
How Do I Estimate Spray Foam Insulation Cost?
To estimate your spray foam project, you'll need two key figures: the surface area you need to cover (like walls and ceilings) and your desired R-value.
When calculating how much foam you need, remember to use board feet, not just square feet. For example, an 8'x20' wall is 160 square feet. But to achieve an R-value of 14 (which requires 2 inches of closed-cell foam, since closed-cell foam is R-7 per inch), you'd need 320 board feet. Remember, one board foot equals one square foot at one inch thick.
How Much Does Spray Foam Expand?
Spray foam's ability to expand is a major advantage. Closed-cell foam expands to about 1 inch thick when applied, while open-cell foam expands to a significant 3 inches thick. This expansion allows the foam to completely fill every crevice and open space, creating an air seal that's far superior to other insulation types.