Spray Foam Or Fiberglass Insulation: What’s Best For You?

by | Jun 15, 2023

We get it. There are already endless decisions to be made when building a house or any other structure. But that is what Best in the West Construction is here for to help you make decisions and develop your project to your exact specifications and needs. So when it comes to the question, “Should I get spray foam or fiberglass insulation?” we’re here to help with that too. 

We feel that spray foam is the best choice, but that’s getting ahead of ourselves. First, let’s look at each of them and what they offer. 


Spray foam insulation is made by mixing two specific chemical compounds, which rapidly expand when mixed. The product is mixed as it is sprayed directly onto the surface needing insulation, and then as it expands, it seals gaps and forms a barrier against air and moisture. Spray-in insulation requires concrete equipment and must be installed by a professional. 


Fiberglass insulation is made of plastic filaments mixed with glass and spun into fibers. The fibers trap air and slow the transfer of heat. Fiberglass insulation comes in rolls or batts that can easily be cut to the size needed.  


There are two types of spray foam insulation: open-cell and closed-cell. The first is filled with cells that are not entirely enclosed. The cells are designed to remain open, which makes the final product softer and more flexible. When applied, the open cell structure expands significantly, meaning you can insulate hard-to-reach nooks and crannies.

The second is like it sounds, with all the cells completely closed. This seals the foam, preventing air and moisture from getting inside it. This makes for a much more rigid and stable kind of insulation. Since the cells are so closely compacted, closed-cell foam is a much denser product, with one application expanding to only about 1” in thickness. Its rigid structure can also add to the structural integrity of a building. 

Spray foam insulation can be applied to wall cavities and exterior walls in your crawlspaces, attics, or gaps and cracks throughout the house. The seal will significantly reduce air leaks, keeping air-conditioned spaces more comfortable and reducing energy costs. It can also help keep dirt, allergens, and other pollutants out of your home. 


When comparing the two, one factor to consider is the R-value. This refers to the insulation’s resistance to heat flow, and the higher the R-value is, the more effective the insulation will be. Spray foam insulation ranges in value from around 3.5–6.5 per inch, depending on the exact kind you get. Fiberglass insulation has a significantly lower R-value, averaging 2–3 per inch. Also, fiberglass insulation can lose its R-value over time, especially if moisture gets to it or it’s not installed correctly and begins to settle. 


Spray foam insulation also has a longer life expectancy than fiberglass, as the components do not break down easily. Fiberglass can be easily torn apart by pests, but spray foam itself is sturdy and provides no food source for pests. 

Spray foam insulation is more of an investment than fiberglass insulation, but its many benefits make it worthwhile. With its long lifespan, durability, and resistance to moisture and pests, you won’t need to replace it soon. If you have any further questions as you make the decisions necessary to finish your project, Best In The West Construction is here to help you with whatever you need.