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Spray Foam Insulation v. Fiberglass? What You Need to Know

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What do you think of when it comes to insulation? Generally speaking, most people consider either spray foam or fiberglass. Cellulose is a third alternative, although not as widely used. So, what’s the difference? And, what makes one more advisable than the other?

The focus of this article is on residential properties. All things considered, many homeowners forget the importance of superior insulation. That is until they get their first energy or heating bill. Then the focus is on making sure no outside air gets in. And, of course, the opposite is true. Good insulation focuses on keeping desired temperatures to the interior of the premises as well.

Differences between Fiberglass and Spray Foam


Just about everybody has a visual of what fiberglass looks like, although there may be questions about how it works. The nature of the product is in its name. Fiberglass is essentially made up of fibers of molten glass. For the most part, fiberglass is sold as batt insulation and comes in a number of colors.

According to a government energy website, the insulating material’s resistance to conductive heat flow is rated regarding its thermal resistance or R-value. This chart provides the suggested R-values for home insulation. The Department of Energy estimates fiberglass has an R-value between 2.9 and 3.8 per inch of thickness.

In any case, there some disadvantages in using fiberglass insulation. For one, fiberglass batts come in predetermined widths that may make application difficult. Consequently, space and air flow may not be covered as intended.

Next, there’s the problem with moisture and mildew. Unfortunately, fiberglass does not work against either. And, if moisture contaminates the fiberglass, the R-value can diminish to almost nothing. Fiberglass can also sag and thus make areas virtually uninsulated.

Spray Foam Insulation


Spray foam insulation is divided into two primary categories. One is open-cell; the other, closed-cell. Closed-cell has the higher R-value, at approximately 6.5 per inch of thickness. Open cells R-value is 3.5-3.7 per inch of thickness.

One of the distinct advantages of spray foam is the ability to apply it in hard to reach crevices. Without question, air leakage is significantly different than fiberglass insulation. And, there is the issue with mold.

Marvel Coatings Open and Closed-Cell Spray Foam Insulation products create a barrier against mold. In some cases, the spray foam may actually add more strength to the walls. As a result, many homes built in hurricane paths are required to use spray foam for insulation.

Spray foam insulation is considered a healthier alternative to fiberglass for many reasons. It creates remarkable savings in HVAC system use. Some say that the difference is as high as fifty percent. Accordingly, decreased loads can actually lengthen the life expectancy of the actual heating and air conditioning units.

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If you are looking for the best insulation for a residential property, you should speak with the experts at Marvel Coatings. We can give you details regarding your job’s specifications. Here’s how to contact us.