As a homeowner, whether it’s a new construction or an existing home, choosing which insulation to use in your home is a costly decision that isn’t taken lightly. As such, with any major decision involving your home, you want to do your proper due diligence and research every avenue you can take. That’s why we’ve put together this guide to help make sure you make the best decision for your home and your family.

How Does It Work?

Spray-Foam-vs-Fiberglass-InsulationAs you know, insulation is used to help keep heat in the home. With traditional fiberglass, this is done by slowing down the transfer of heat using glass fibers that trap air bubbles. These bubbles create an insulating effect that slow down the heat exchange process between the inside of the home and the outdoors. Spray foam contains a polymer, such as polyurethane, and a foaming agent. After being sprayed, the foam expands roughly 40-120 times (depending on foam type) its original size and hardens into a solid. As a result of this expansion, it’s able to fill vacant air gaps and get a more complete seal in comparison to fiberglass insulation. Also, it will expand and contract in relation to the building.

Energy Efficiency of Spray Foam Insulation vs. Fiberglass

what is r-value infographicBy it’s own nature, fiberglass insulation does not stop air from traveling through it, as it needs the air to pass through to create the air bubbles that make up its insulating effect. On average, you lose more than 30% of your heat when fiberglass is installed, if installed poorly, it can leave open spaces around fixtures (i.e. your outlets) allowing even more heat to escape. Spray foam, as mentioned above, fills all spaces, preventing air from escaping. Overall, spray foam insulation is much more efficient than fiber glass and has a higher R-value.

What Is R-Value?
R-value is an insulation material’s resistance to heat flow. The higher an R-value the more heat it prevents from escaping through the insulation. Fiberglass insulation normally has a very poor overall R-value, even when using a high R-value fiberglass insulation (such as a R21 roll of insulation), the highest rating you can normally achieve with it is an R17. The most common rating that you get from a contractor installing this style of insulation usually results in an overall R-value of R13. However, this is the opposite where spray foam is concerned, the colder it is outside the better it performs.

Cost of Fiberglass vs. Spray Foam Insulation
Overall, spray foam insulation, on average, can cost up to three times the cost of fiberglass insulation. Spray foam, however, lasts a lifetime and creates a much more efficient layer of insulation by reaching areas that traditional insulation just can’t reach. With its higher energy efficiency, which in turn causes lower heating bills, you can see a payback period on the insulation within 3-5 years.

Spray Foam vs Fiberglass

Foam Fiberglass
R value per inch R3.8-R7 per inch R3.5 per inch
Water Resistant Yes* No
Air Barrier Yes No
Mold Resistant Yes No
Rodent Resistant Yes No
Structural Strength Yes* No
Life Expectancy 80+ years 10-25 years
Forms to structure Yes No

* Only Closed Cell Spray Foam Insulation