What Is Fiberglass Insulation Used For? (Benefits and Types)


You may have heard of the word “fiberglass,” and may be surprised to learn how this material helps in our daily lives. This word has been known to cause confusion, so let’s clear it up now.

Fiberglass is known as “acoustic insulation” and is used to reduce element transfers between structures. The purpose of fiberglass insulation is to prevent excess sound, heat, or cold from spreading, keeping rooms at a steady temperature with little noise.

There’s more you should know about fiberglass insulation, so keep reading to learn how to use it for the best results.

What Is Fiberglass Insulation Made Out Of?

Fiberglass insulation is created by first taking large pieces of molten glass softened by fire, breaking them down as small as possible, then spinning them into a soft, yet strong and thick material.

Based on the International Association of Certified Home Inspectors (InterNACHI) standards, the manufacturers of this material will use between 40% to 60% of recycled glass in each batch.

Other earthly materials are added into the mixture to create a thicker insulation, making it more dense and more effective. Some of these natural elements include but are not limited to:

  • Soda ash
  • Silica sand
  • Limestone
  • Borax

Other forms of indigenous rocks like nepheline syenite, kaolin clay, and even feldspar are also used to create the fibrous protective material and helps to absorb moisture and keep sounds isolated to their designated room.

Many creators of the insulation material will also include an aluminum oxide called calcined alumina to keep the material fresh from gasses that cause decomposition. Fiberglass also contains a liquid resin during molding to chemically bond and cure it.

How Fiberglass Insulation Work?

Once fiberglass is made into the forms of blow-in, batts, or rolls, it is used by home renovators to warm your house from the inside out by placing several layers of it in between the walls of your home.

The soft and heavy insulation is also typically placed in areas that are prone to excess moisture and molding like basements, floors, walls, ceilings, and even between small studs and ducts.

Fiberglass retards the spread of heat, cold, and sound conduction by trapping them in small air pockets, only allowing what is necessary to escape while storing or diffusing the excess.

The light-weight, yet strong material also determines how much air should be traveling through your home, making it a natural temperature regulator so that you don’t become too cold or too hot – even when your air conditioning is blowing.

You can determine the strength and efficiency of the fiberglass by the R-value; the bigger the number, the better the effectiveness. Most fiberglass R-value ranges between 2.2 and 4.5 per inch, with 3.5 being an industry standard for high-quality insulation.

Pros and Cons of Fiberglass Material

The upside of fiberglass is that it insulates your home from water and surplus air leakage. Other benefits include:

  • Saves money on energy: The thermal dynamics of the material insulation is densely packed, causing less air to float around, thus, more regulated energy. This can help you decrease your home temperature bill by 40% on average!
  • Fire retardant: Because of the mineral rocks ingredients like sand and limestone, fiberglass doesn’t catch fire. Additionally, some materials are treated with fire retardant resin for extra safety.
  • Saves the planet: Fiberglass is made of up to 60% of recycled glass, with the remaining 40% being of indigenous rock. These inexpensive materials are saved from landfills, helping to reduce greenhouse effects by 20% on average.

However, with every good, there’s a not-so-good alternative:

  • Mold: After significant years of using the same material, the collected moisture and heat can create a mildew and mold spores that hide in the air pockets of the material. Yet, swiftly replacing it cures that problem.
  • Required Coverage: Based on housing structures, it can take an ample amount of fiberglass to insulate your entire home including the walls, ceiling, and odd nooks and crannies, which could cost a pretty penny.
  • Health Concerns: The chemicals found in fiberglass may cause irritation of the eyes, skin, and lungs if your body is in direct contact.

How Long Does Fiberglass Insulation Last?

With intentional and proper packing, fiber insulation can last up to 80 years! Its lifespan is estimated on the amount that is used, along with the indigenous rocks and chemicals added to it. Keep in mind that this long life can be shortened based on several key factors.

One of them is water; the more wet the fiberglass becomes, the less effective it will be over time. Human interference can split the matts or barrels apart, making the fiberglass lose strength.

Also, when the natural material becomes matted (thick, intertwined tangles), air can’t move through, thus reducing the effectiveness of its thermal regulation ability.

Which Type of Fiberglass Insulation Is Best?

Before determining the best insulation, here’s a quick list of the different types of fiberglass insulation:

  • Batts: Large cut strips of fiberglass packaged in non-toxic paper in rectangular shape. Batts are commonly used because of neatness and efficiency of packing it.
  • Rolls/Barrels: A full sheet of fiberglass that is “rolled” up for distribution, then unraveled during installation. Barrels are easy and fast to install by simply unrolling it, and placing it in your area of choice.
  • Blown-in:  Shredded, cotton-like filaments that are “blown-in”to your selected area. This can be used as a fast way to cover floors, or fill in challenging spots.

Batts are a common choice because they are already packaged and simply need to be placed into the structure; the shortcoming is that it is not great for hard-to-reach places.

Rolls are a good option as well, yet since it’s in one piece, you may have to cut and structure it to the shape of the location, leaving excess pieces behind. Blown-in is chosen as a convenient way of getting the job done, and does a better job at filling expensive air gaps.

The best option comes down to your style and level of work energy. Barrels require the most energy, batts come prepackaged – but requires lifting, while the work of blown-in is done by a machine that you simply have to point and shoot.

How Much Does Fiberglass Insulation Cost?

The average cost of fiberglass insulation is between $0.64 and $1.64 per square foot. Overall, expect to between $1,800 to $3,000 for insulation if your house is between 1,200 to 2,000 sq ft.

You should know that fiberglass is fairly inexpensive to purchase, but the price of labor is what skyrockets the price. The equipment needed, including a hopper for blown-in insulation, will also increase the cost of labor and your overall bill.

However, if you choose to make this a DIY project, the cost of labor is extracted and the price significantly lowers to the price by more than half, bringing a new cost to the range of $800-$1,500!

It’s safe to say that being your own labor will save you way more money, making the investment of insulation even more worth it.

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