Fact Checked

What is Fiberglass Insulation?

Mike Howells
Mike Howells

Fiberglass insulation is a man-made construction material used to limit thermal changes, as well as sound transmission, in buildings. It is composed of bundles of very thin strands of glass, which has a high surface area-to-weight ratio that makes it a lightweight, cost-effective, and practical option for both residential and commercial applications. Fiberglass insulation is packaged in rolls that are installed along the walls and ceilings of a building during construction.

Though fiberglass as a material has existed since around the turn of the 20th century, the first fiberglass insulation was developed and available for sale in 1938. Initially a competitor to asbestos, the then-standard insulating material, it gained popularity as widespread understanding of the carcinogenic qualities of asbestos grew in the 1960s and 1970s, and forced builders to look for alternatives. With many of the same characteristics as asbestos, fiberglass was a natural option and quickly embraced.

Handling fiberglass insulation may cause eye irritation.
Handling fiberglass insulation may cause eye irritation.

Beyond its relatively light weight and cheap cost to manufacture, fiberglass has a number of intrinsic qualities that make it a good insulating material. The many fibers of glass bundled together are excellent at trapping heat. In this way, a fiberglass-insulated building is far better at retaining a set temperature than a non-insulated one, which means lower energy costs for both heating and cooling. For the same reason, fiberglass insulation is highly effective at reducing sound, and is also non-combustible and non-absorbent. It is important to note that fiberglass also does not wear out or lose efficacy over time.

With roughly 90% of all American homes using fiberglass insulation, and a similar level of popularity across the developed world, manufacturers of fiberglass insulation have responded to increased global awareness about conservation. Therefore, a significant amount of fiberglass insulation is now made using recycled materials. Owens CorningĀ®, the company that first sold fiberglass as an insulation product in the 1930s, began offering insulation in 2009 that contains up to 40% recycled glass.

Fiberglass insulation is not without its negatives, however. Though its proponents contend it is one of the most thoroughly researched products on the market, and point to its recent removal from the International Agency for Cancer Research's list of possible carcinogens, some studies have shown an heightened prevalence of lung cancer among workers in fiberglass factories. Many builders and consumers now choose to avoid it for that unproven, yet troubling, reason.

Other downsides to using fiberglass insulation include eye, skin, and lung irritation when handling and installing it. Though long-term consequences remain a subject of debate, breathing apparatus, protective eye-wear, and gloves should always be used when around bare insulation.

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Discussion Comments


@Animandel - There are several environmentally friendly insulation choices on the market currently. I have been weighing an attic insulation product made out of old newspapers to see how it stacks up against the traditional fiberglass insulation. Surprisingly, the recycled newspaper product is fire resistant. This is a primary concern for me.


@mobilian33 - The new stuff is always better and safer until we find out that it isn't. As this article mentions, fiberglass insulation replaced the old asbestos insulation. When the asbestos came out, everyone thought that was the greatest stuff ever. And we now know how wrong we were about that.

I imagine the fiberglass is better than asbestos, but it isn't perfect, and neither will the next big thing be perfect. Somewhere in the future we will probably learn that spray foam insulation is harming us in some way.


Whenever someone recommended any type of installation for our home in the past, they have always said go with fiberglass insulation, so I have assumed that this is safe insulation. We have always used fiberglass insulation in our attics. Now I am wondering if we made a good decision choosing the fiberglass.

I read an article the other day regarding a connection between fiberglass insulation and cancer, and this scared me. We have been breathing whatever this insulation puts into the air and we have been touching the actual insulation when we go into the attic. We picked this type of insulation because we thought it was safe, and now to learn that we may have been putting our family in danger all of this time is very frustrating to say the least.

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    • Handling fiberglass insulation may cause eye irritation.
      By: Rob hyrons
      Handling fiberglass insulation may cause eye irritation.