Will Fiberglass Insulation Burn? Here are Things You Should Know About

Look for high R-values as well as safety while purchasing insulation. Flammability is a vital factor to consider. After all, no one wants to install flammable insulation. When fiberglass comes to your mind for your insulation, you might have a question pop in your mind ‘will fiberglass insulation burn?’ Let’s take a closer look at this.

Fiberglass insulation products, manufactured from a combination of silica sand, limestone, and soda ash, are often used in homes due to their fire retardant properties. The glass is made from sand, and the limestone and soda ash lessen the melting temperature required to make it.

Borax and other substances such as feldspar, magnesite, and kaolin clay are used to improve the performance of the fiberglass.

The components must be heated once they have been blended. After that, to create a solid fiberglass, it needs to be heated to a temperature of 2,500°F.  Glass can be turned into glass wool, filaments, or fibers once it has been molted.

Will Fiberglass Insulation Burn?

The answer to the question, ‘will fiberglass insulation burn?’ especially when considering fire safety measures during installation, is not a straightforward yes or no, as it is with many things in the building.

We’ll explain why, even though fiberglass insulation does not burn, it can contribute to a house fire. We’ll also talk about how flammable an alternative to fiberglass insulation is.

will fiberglass insulation burn

When safely installed, fiberglass insulation will not burn but can melt at high temperatures. This highlights the importance of adhering to local building codes when installing fiberglass.

Brown paper, commonly used as a vapor barrier on batts, can catch fire, posing a fire hazard. Blown-in fiberglass insulation flammable concerns are minimal, as it is non-flammable but requires specialist equipment.

What Temperature Will Fiberglass Insulation Burn?

Even though fiberglass insulation will not burn easily, it can melt if heated to a high enough temperature. Fiberglass is supposed to melt at temperatures above 1,000 degrees Fahrenheit (540o Celsius).

Other insulation materials, such as cellulose and mineral wool, can endure higher temperatures without melting. Vermiculite melts at 1,400o Fahrenheit (760o Celsius), while ceramic fiber and mineral wool will melt at 2,200o Fahrenheit (1200o Celsius).

If I Want to Throw Away My Old Insulation, Can I Burn It?

If you plan to dispose of old fiberglass insulation batts, remember that these materials, particularly those with a craft paper or foil front, can contribute to an insulation fire.

Although the fiberglass will not burn, the paper and foil facings will. Fiberglass, particularly batt-type fiberglass, does not settle with age.

Is It Safe to Burn an Old Insulation?

Another thought you might have before burning fiberglass insulation is ‘is it safe to burn insulation?’ You should be aware that burning old fiberglass insulation is quite poisonous and can burn very quickly depending on the amount of resin in the fiberglass.

Because it’s made of plastic that’s been strengthened with tiny glass fibers. In smoldering fiberglass, poisonous formaldehyde vapors and other harmful compounds are released. Formaldehyde causes instant eye discomfort, headaches, and skin irritation, as well as the possibility of cardiac and respiratory mortality.

The Correct Way to Throw Away Your Old Insulation

If having old insulation is your problem and you need to throw it away immediately, burning it will just add another problem. All you need to do is wrap all your old insulation first. You may need contractor bags to carry such a huge load.

After that, you can contact your county’s waste management department or your local garbage authority. The personnel there will point you toward the nearest specialist trash disposal facility, which is usually a construction-materials disposal facility.

In some situations, you may be required to pay a small fee to dispose of fiberglass insulation at the job site. You face a higher fee if you dispose of the insulation in your home’s garbage containers or dumpster.


So, now you know that fiberglass can’t be burned, you won’t be able just to discard old insulation in the trash bin. If you asked, ‘will fiberglass insulation burn?’ Regarding safety, the answer would depend on what kind of construction you have.

Read also: How Long Does Fiberglass Insulation Last

While fiberglass insulation catching fire is rare, it’s crucial to understand that different types of insulation, including fiberglass, have varying levels of fire resistance.

Fiberglass insulation is naturally fire resistant due to its composition, but it can still contribute to flame spreads if not properly installed.

Popular insulating materials like fiberglass often contain plastic polymers, which can create air pockets that enhance insulation but may affect fire resistance.

Yes, it will melt in a certain heat, yet it is still not combustible since it was created to resist fire. But that doesn’t mean you can throw away your old insulation by just burning it. Follow the correct procedure for disposing of your old insulation.

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Insulator is a skilled author and Insulation expert with years of experience in the field. He has authored several articles and books on various aspects of insulation installation, maintenance, and repair.