Compare Insulation Performance: Cellulose vs. Fiberglass

Posted On: March 03, 2013

Temperature extremes in the winter and summer make a home’s insulation of the utmost importance for maintaining a comfortable indoor climate. Homeowners have the choice of using cellulose or fiberglass insulation, and it’s important to understand the differences in insulation performance of each.

Fiberglass insulation is made of spun glass fibers that are layered in a mat. It is usually pink or yellow, resembling cotton candy — the type of insulation most people are familiar with. Cellulose insulation is made of paper fibers and chemicals mixed together. It is a loose composition, meaning that it typically has to be blown into an area you want insulated.

Insulation performance between the two varies depending upon a number of elements. Differences that homeowners need to be aware of include:

  • Installation. Fiberglass is laid in strips. Cellulose must be blown into the cracks and crevices of your home. As cellulose insulation is denser, it has the same R-Value — the measurement of how well it blocks thermal transfer — as a thicker fiberglass insulation. The application of blown-in cellulose fiberglass also leaves fewer gaps. Studies have shown that cellulose insulation allows less outside air into your home than fiberglass.
  • Moisture. Moisture is bad for both types of insulation, greatly impacting insulation performance and R-Values. Cellulose insulation will retain water at a higher rate than fiberglass. Since it already has a measure of water in its composition, it needs some drying time to ensure that it does not retain moisture behind your drywall.
  • Fire. Both types of insulation have been made to withstand fire. Fiberglass insulation is not very flammable. However, once it ignites, it does emit toxic gases. Cellulose fiberglass is treated with a fire retardant. It will actually act as a fire barrier, slowing a fire down.

While fiberglass insulation may be easier to install — generally professionals are needed for blown-in cellulose insulation — most experts agree that the biggest factor that affects insulation performance is how well it’s installed. Contact us at Ernst Heating and Cooling for all your home comfort needs. We have been serving the Metro-East area since 1951.

Our goal is to help educate our customers in Hamel, Illinois and surrounding areas about energy and home comfort issues (specific to HVAC systems).  For more information about insulation performance and other HVAC topics, download our free Home Comfort Resource guide. 

Image courtesy of Shutterstock

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