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Cellulose vs Fiberglass Insulation

Cellulose vs Fiberglass Insulation

You know you need new insulation but with so many options on the market today how do you know which is best for you? One common question we get is, “what’s the difference between Cellulose vs Fiberglass Insulation”? This is a great question as there are many similarities between the two. Despite their similarities, however, there are some factors that set them apart. Here we discuss the details of each so you can make an informed decision about which would be best for you.



Cellulose is insulation manufactured from a minimum of 75% recycled paper. Being made from paper it is grey and fluffy and installed by being sprayed into walls. As its name suggests, fiberglass insulation is made from extremely fine glass fibers. It’s manufactured and installed in sheets.


Both cellulose and fiberglass are easy to install but because fiberglass is manufactured and installed in sheets, it’s more difficult to properly fill difficult places. Cellulose is sprayed in which fills tighter spaces more effectively and decreases the room for error make insulation slightly easier.

Extreme Cold

When it gets cold like it does here in the midwest, these two insulations respond differently. Fiberglass insulation drops significantly in R-Value, whereas cellulose retains it’s r-value quite a bit more compared to fiberglass.

Green Factor

The way these materials are manufactured is quite different. Cellulose production is simple and is made from mostly recycled paper. Sometimes fiberglass is made with upcycled glass that is melted and spun into fibers, but most times it’s made from raw materials. This makes cellulose’s embodied energy less and a greener option.


Both fiberglass and cellulose are cost-effective options that hold just about the same R-value (between 3.5 and 3.7 per inch) which is one of the main reasons they are often compared to one another. They both will help retain heat, but some disadvantages they have in common are that they can’t act as an air barrier, aren’t a fan of moisture, and are susceptible to wind-washing – something that takes place when the wind blows loosely installed insulation.


Cellulose and fiberglass are both cost-effective insulation options. Ultimately, which option you choose will depend on the project at hand. You may even want to consider other options like AirKrete or spray foam for certain areas of your home. AirKrete is an option worth exploring as it is the greenest on the market today and installed by being pumped into all exterior wall cavities making it one of the most effective choices. Contact Streamline Enterprises to discuss your options. We can help you choose which is best for you.