No matter the season, insulation plays an integral role in determining how comfortable your home is. The wrong choice or improper installation of your insulation could cause your heating and cooling bills to skyrocket.

Blown-in fiberglass and cellulose are two of the most common choices for insulation, and while very similar, each has its drawbacks and advantages, so it’s best to be fully informed before deciding which material is best for your home.

The Basics

Loose-Fill Fiberglass

Loose-fill fiberglass is comprised of tiny glass-spun fibers. It’s lightweight and the most commonly-used type of insulation, being especially popular within the new housing market. It also is generally less expensive than cellulose insulation, though prices vary.


Cellulose is a paper-based insulation material. It’s made from wood, newspaper, cardboard, and other recycled materials, making it popular with homeowners or builders looking to make the eco-friendly choice. It tends to be heavier than fiberglass due to the fire-retardant chemicals added during production.

Comparison Factors


The R-value is the measurement of how well a material insulates; the higher the R-value, the better insulation it provides. The R-value your house needs is determined by your geographic location and can be found using this map.

If you’re DIYing, most insulation available in stores will be marked with an R-value and a chart to help you figure out how thick to blow the insulation. To reach a higher R-value, you’ll need more insulation.

The R-value of fiberglass ranges from R-2.2 to R-4.3 per inch, depending on whether it’s blown into the attic or wall. Fiberglass can be compressed without affecting the R value. For cellulose, it’s around R-3.2 to R-3.9 per inch—typically on the higher end of the range when used in walls.


Fiberglass insulation comes in loose-fill form as well as batts, which are long strips of insulation. Batts are popular with DIYers because of their ease of installation, but the strips need to be cut to fit around wires, pipes, and lights, which has the potential to leave gaps in your insulation if done poorly.

Loose-fill fiberglass produces better results but is slightly harder to install, which is why its best left to the professionals. Fiberglass can irritate the skin and lungs, so if you do decide to tackle the project yourself, suit up with a respirator, gloves, and long sleeves.

Cellulose insulation is always blown in. Some forms are dry, intended to be added to finished walls, and some include an added adhesive to allow it to be blown into open walls.

Fire Risk

Both fiberglass and cellulose pose a relatively low fire hazard. Because it’s made of glass, fiberglass is almost completely non-flammable, though the glass could melt if exposed to extreme heat. Cellulose is treated with fire retardants during production, but if not properly installed, it can be combustible.


Fiberglass is often cited as less effective at insulating in extreme cold or heat according to a 1991 study done by Oak Ridge Laboratories; however, Andre Omer Desjarlais, employee Oak Ridge, explains in an interview, “This was true 20 years ago, but all fiberglass manufacturers have changed their products appreciably since then, and this is simply no longer an issue.”

Because fiberglass is lightweight and doesn’t absorb moisture, it’s unlikely to settle, but it doesn’t deter insects or other pests from invading your home. Because it can have a lower R-value, loose-fill fiberglass is best used in places where it can be layered for increased insulation, like attic floors.

Cellulose is more resistant to airflow than fiberglass, but with a settling rate of 20%, the effectiveness of cellulose insulation can decrease over time. However, the borates used to make cellulose insulation flame-retardant also act as a pest deterrent.

When it comes down to it, the important thing to remember is that some insulation is always better than no insulation. No matter which material you decide is best for your home, it’s important it’s installed correctly to ensure you’re getting the maximum protection possible.

At Minnesota Home Improvement, we have over 40 years of construction experience. We select high-quality loose-fill fiberglass and cellulose to make sure your home stays cozy or cool year-round. Visit our website for more information, or contact us online for a free quote.