Is Fiberglass Insulation Flammable? Here is the Answer

Is fiberglass insulation flammable? Before answering this, it’s important to compare it with other insulation types, such as cellulose insulation, to understand its properties and safety features.

The combination of limestone, silica sand, and soda ash is not only useful for making fiberglass but also contributes to its flame resistance, unlike some insulation products that burn easily. This silica sand is useful for making glass, while soda ash and limestone reduce the melting point required.

Borax, feldspar, kaolin clay, and magnesite are used to improve the performance of fiberglass, often treated with fire retardant chemicals to enhance safety.

Thus, all components need to be cooked after combining. Fiberglass, which includes fiberglass and mineral wool insulation, needs to be burned to 2,500 degrees Fahrenheit, a temperature much higher than what is required to ignite cellulose insulation.

is fiberglass insulation flammable

Fiberglass items, often used in exterior walls, require additional coatings like lubricants and anti-static compounds to prevent heat transfer and improve handling. When shaping the fiberglass, often backed with kraft paper, additional components like lubricants are involved, which can influence its fire hazard by the Consumer Product Safety Commission.

An additional additive or anti-static covering can be an extra component. It allows the fiberglass to form, pack, and ship.

The house includes windows, baths, roof panels, and insulation needs like fiberglass. It is most certainly present in your automobile, and it is also present in your boat.

When selecting insulation, look for high R-values that are also safe. Flammability is an important consideration; no one wants to install flammable insulation.

So, is fiberglass insulation flammable? And how flammable is fiberglass insulation?

Fiberglass insulation cannot catch fire, although it may melt at high enough temperatures. Nevertheless, the brown paper, frequently used as a covering on batts, might catch fire. Then, blown-in fiberglass is likewise non-flammable, although installation necessitates the use of specialist equipment.

Like many other questions in construction, the answer is not as simple as yes or no.

Can Fiberglass Insulation Burn?

Though fiberglass insulation is not able to burn, it can melt if heated sufficiently. Fiberglass has a design that can melt at greater than 1,000° F or 540° C.

Other insulating materials can withstand greater temperatures before melting. Mineral wool as well as ceramic fiber, melt at 2,200° F or 1200° C, but vermiculite requires 1,400° F or 760° C to melt.

When installing the fiberglass insulation, you need to look around for some fire sources in your home, such as a chimney. It may reach temperatures of over 1,700° F, so whether you own a chimney fire, this non-flammable insulation may melt.

Whether fiberglass melts or not, it might trigger several issues. One of them is that the fiberglass begins to distribute the fire to other flammable components.

When fiberglass melts, it expands and unleashes stored gasses such as oxygen. High oxygen fuels the fire and transforms a hollow barrier into a heat chamber. Surprisingly, the non-flammable fiberglass might accelerate a fire.

Read also: Rockwool Insulation vs Fiberglass

This has been demonstrated in a number of fire demonstrations. A ceiling fell within 20 minutes in a fiberglass-insulated structure, and the entire structure burned within two hours. Other insulating materials could last longer in the same trial (source).

How Flammable Is Fiberglass Insulation?

Well, because glass constructs the insulation, it cannot trigger a fire or is non-flammable. The foil and paper backings, on the other hand, can catch fire. Flame-retardant adhesives plus foils can be additional materials used by fiberglass producers to craft paper backings.

An FSK shield, which can also be useful as a vapor barrier, is one such product. Deploying an FSK-shield appliance with the foil side uncovered will inhibit flame spread.

While fiberglass insulation is generally considered naturally fire resistant, it’s important to be aware of the potential risks associated with its installation and use. Inadequate installation or exposure to high temperatures can compromise its safety.

So, those are some answers to “is fiberglass insulation flammable?” The conclusion is no. Surely, this is the recommended insulation to wrap up your house’s walls.

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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.