Is fiberglass insulation a thermal barrier?

Author: Carter Mertz  |  Last update: Sunday, December 14, 2025

Fiberglass has always been one of the most common insulation materials on the market, due to its strong performance in a variety of areas. Widely known for its high thermal resistance, fire resistance and sound absorbency, it is also an effective weapon against moisture and mold damage.

Does fiberglass insulation need a thermal barrier?

Luckily, most building codes require that insulation be protected with a barrier so that even if your insulation catches fire, you'll be protected.

Does fiberglass insulation keep heat out?

These pockets trap the air and disrupt the flow of heat, making the insulation a poor conductor of thermal energy. In other words, fibreglass insulation helps keep heat out of your house during summer and helps you keep the warmth in during winter.

Is fiberglass a good thermal insulator?

Fiberglass is an attractive choice for home insulation because it poses no fire hazard. According to some estimates, thermal insulation (made from fiberglass and its alternatives) conserves 12 times as much energy as is lost in its production, and it may reduce residential energy costs by up to 40%.

What is the biggest problem with fiberglass insulation?

Air Leakage

Fiberglass insulation is less dense than other types of insulation and does not create an airtight seal, which means air can travel freely through the insulation. This is called air leakage and it's one of the most common sources of energy loss in a house.

Mineral wool vs fiberglass insulation | everything you need to know

What is a disadvantage of fiberglass insulation?

Fiberglass batt insulation does have some drawbacks. They can be itchy and irritating to handle, and inhaling the fibers can cause respiratory problems. It's important to wear protective clothing and a mask when handling and installing fiberglass batts.

Why is fiberglass not good?

Exposure to fiberglass can cause irritation in the eyes, nose, or throat. It may also cause itching and irritation when the fibers get stuck in the skin.

Is fiberglass insulation heat proof?

The primary component of fiberglass is silicon dioxide (SiO₂), which is the same as glass. Fiberglass insulation materials are inherently non-combustible and belong to inorganic fire-resistant materials. Fiberglass insulation can typically withstand temperatures exceeding 1000°C (1832°F) without burning or decomposing.

When did they stop using fiberglass insulation?

However, “by the late 1970s consumers and health organizations established a solid link between asbestos and lung disease. In 1980, asbestos production was banned throughout the U.S. and many other countries” (hunker.com). As a result, cellulose insulation was introduced as an alternative to fiberglass.

What is the best material to insulate against heat?

Summary
  • Aerogel is more expensive, but definitely the best type of insulation.
  • Fiberglass is cheap, but requires careful handling.
  • Mineral wool is effective, but not fire resistant.
  • Cellulose is fire resistant, eco-friendly, and effective, but hard to apply.

At what temperature does fiberglass insulation melt?

Generally, fiberglass has a melting point that ranges from around 1,000 to 1,400 degrees Celsius (1,832 to 2,552 degrees Fahrenheit). This high-temperature tolerance makes fiberglass insulation a practical choice for applications where heat resistance is crucial.

Does insulation block out heat?

Insulation in your home provides resistance to heat flow and lowers your heating and cooling costs.

Do they still use fiberglass in insulation?

Insulation 101

Today, the two most common, safe and cost-effective options are Cellulose and Fiberglass.

Does fiberglass insulation keep out heat?

Most insulation materials prevent heat loss through conduction, but reflective materials like radiant barriers work a bit differently. Fiberglass insulation traps heat when it's moving to a colder area — from outside to inside your home in the summer and from inside the house to outside in the winter.

What counts as a thermal barrier?

A thermal barrier is a material that is applied between spray foam insulation and the interior living space. Moreover, the IRC says that all foam plastic insulations have to be separated from the interior of the building by a 15-minute thermal barrier. One such barrier is half-inch gypsum board (drywall).

What is the biggest problem with Fibreglass insulation?

Moisture and allergens can be get trapped inside fiberglass

It doesn't happen often but when it does it may cause serious damages to the resident's health. People who suffer from allergies are more affected. Dust, allergens, and moisture can be trapped inside fiberglass and lead to mold growth.

Why is fiberglass banned?

The potential health effects of fiberglass exposure

However, just as with the chemical flame retardants, fiberglass carries its own set of adverse health effects when it escapes into the environment. For example, airborne fiberglass strands can cause skin irritation and respiratory problems when inhaled.

Is there better insulation than fiberglass?

Mineral Wool Insulation

In many ways, mineral wool is a superior insulation product. It has a higher R-value per inch compared to fiberglass, about a 22-37% higher R-value. It contains 70% recycled material, making it a greener product than fiberglass at 20-30% recycled material..

Is fibreglass a thermal insulator?

Fiberglass insulation works by trapping air within its fibres, which helps to slow the transfer of heat between the inside and outside of a building. This makes it an effective way to keep your home or office warm in the winter and cool in the summer.

What temperature can fiberglass withstand?

Due to its composite, inorganic nature, fiberglass can withstand some of the most extreme temps while still maintaining its form. Fiberglass can retain 50% of its strength at 700° Fahrenheit (371° Celsius) and 25% of its strength at 1000° Fahrenheit (538° Celsius), making it ideal for industrial use.

How to get rid of fiberglass insulation?

After removing the staples, simply roll out and fold the fiberglass insulation individually. It's best to start from the farthest corner of the room. Discard them in large garbage bags. Talk to your local waste management department to know where you can take them for proper disposal.

Is fiberglass cancerous?

People who work with fiberglass or who have worn-out duct work lined with fiberglass in their homes or workplace may have long-term exposure to fiberglass. There is no evidence that fiberglass causes cancer in people.

Is it safe to sleep in a room with exposed insulation?

Health hazards of interacting with exposed insulation include: Risks of skin, eye and lung irritation. Potential for mold and mildew growth. Risk of increased health problems for kids, as uncovered insulation isn't child-proof.

Is fiberglass insulation bad for your lungs?

Short-term Exposure

The symptoms of irritation are often nonspecific, temporary, and may include itching, coughing, or wheezing. High levels of exposure to airborne fiberglass may aggravate existing asthma or bronchitis-like conditions.

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