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 popped in your mind ‘will fiberglass insulation burn?’ Let’s take a closer look at this.

Fiberglass is manufactured from a combination of silica sand, limestone, and soda ash. The glass is made from sand, and the limestone and soda ash lessen the melting temperature required to make it.

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

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?’ is not a straightforward yes or no, as it is with many things in building. We’ll explain why, despite the fact that fiberglass insulation does not burn, it can nonetheless contribute to a house fire. We’ll also talk about how flammable an alternative to fiberglass insulation is.

will fiberglass insulation burn

Fiberglass insulation will not burn, but it will melt at high temperatures. Brown paper, which is commonly used as a vapor barrier on batts, can, however, catch fire. Blown-in fiberglass is likewise non-flammable, but it requires specialist equipment to install.

What Temperature will Fiberglass Insulation Burn?

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

Other types of insulation can endure higher temperatures without melting. Vermiculite melts at 1,400o Fahrenheit (760o Celsius) (1200o Celsius). While ceramic fiber and mineral wool will melt at 2,200o Fahrenheit (760o Celsius).

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

If you have plans on burning an old fiberglass insulation batt, keep in mind that fiberglass batts with craft paper or a foil front are flammable. 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 that you might have in mind before burning fiberglass insulation is ‘is it safe to burn insulation?’ You should be aware that burning old fiberglass insulation is quite poisonous and, depending on the amount of resin in the fiberglass, can burn very quickly.

Because it’s made of plastic that’s been strengthened with tiny glass fibers. In the process of smoldering fiberglass, poisonous vapors of formaldehyde 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 in the direction of the nearest specialist trash disposal facility, which is usually a construction-materials disposal facility.

You may be required to pay a small fee to dispose of fiberglass insulation at the job site in some situations. 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 to just discard old insulation in the trash bin. If you asked, ‘will fiberglass insulation burn?’ In terms of safety, the answer would depend on what kind of construction you have.

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 way to dispose 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.