Fiberglass Insulation: The Best Attic Insulation

attic insulation

When it comes to insulating your home or business, making the right choice can be difficult with many options available to choose from. Two popular insulation products are fiberglass and cellulose.

We install fiberglass attic insulation in our attic efficiency upgrades.  Let's learn why...

Insulation Basics

Before we dive into the comparison, let’s review what insulation is and how it works. Insulation is a material used to slow down or block the movement of heat between two locations such as a hot attic space and the cooler living space below. Insulation on the attic floor acts as a thermal barrier, preventing heat transfer between unconditioned attic space and the living space below. Basically, the insulation traps pockets of air and hinders its movement. The insulation material's resistance to heat flow is measured by its R-Value; the higher the R-value, the better the insulation's effectiveness.

Cellulose Insulation

Cellulose insulation is an eco-friendly insulation made from recycled paper materials like newspaper, magazines and cardboard, making it an environmentally conscious choice for homeowners. It is typically installed as a loose-fill material in attics or wall cavities because it can fill the smallest of gaps and crevices effectively allowing it to create a more airtight seal and increasing the energy efficiency in your home.

Additionally, cellulose insulation has a higher R-value per inch compared to fiberglass, meaning it’s more effective at preventing heat transfer when compared to fiberglass in the same number of inches.

However, cellulose insulation does have a few negatives. It can absorb moisture more easily than fiberglass, potentially leading to mold or rot if not properly installed or protected. Additionally, it may settle over time and decompose turning to dust, reducing its thermal effectiveness (R-Value) resulting in the need to install more insulation.

Probably the most concerning issue with cellulose insulation is that it’s been manufactured with chemicals like adhesives, boric acid, and pest control insecticides to reduce flammability and control pest infestations. These chemicals can cause difficulties for people with chemical sensitivities.

Fiberglass Insulation

Fiberglass attic insulation has been a go-to choice for homeowners for many years, thanks to its affordability and longevity. Made from glass fibers, this type of insulation is available in rolls, batts, and loose-fill form which is the most common insulation material installed in attic spaces because it can be blown into even the smallest areas of the attic.

Fiberglass insulation offers significant benefits. Unlike cellulose insulation, fiberglass is naturally resistant to moisture, ensuring that your attic remains protected against harmful fungi and microbial growth. It offers excellent fire resistance due to its composition. With a higher melting point than cellulose, it retards the spread of fire, providing a vital safety advantage. Fiberglass insulation can also last up to 30+ years because it doesn’t degrade and compress like cellulose insulation does. It is airy and lightweight making it an excellent choice for managing heat in attic spaces.

One drawback of fiberglass insulation is that it can cause skin and respiratory irritation during installation. However, modern fiberglass insulation products are now available with better user-friendly features, including protective coatings and low-dust formulations to minimize these concerns. Choosing a professional with expertise in installing fiberglass insulation eliminates any irritation concerns.


Fiberglass insulation is the clear choice attic insulation winner for RadiantGUARD-PRO. Cost effective, mold and mildew resistant, long-lasting, fire-retardant, and lightweight, we install blown fiberglass insulation in attic spaces. Contact RadiantGUARD-PRO today for a free assessment of your attic insulation levels and personalized efficiency recommendations.

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