Insulation 101: Fiberglass

As one of the most recognizable insulations on the market, fiberglass is a type of insulation that is either blown-in or installed in batts. As its name suggests, it’s made out of molten glass that’s spun into tiny fibers, a lot like how cotton candy is made, which contributes to its distinguishable appearance.  

Mold and Fire

Because the primary component of this insulation is glass, there are beneficial qualities from the inorganic material. It does not feed mold or mildew and it’s naturally noncombustible. However, it can melt under extreme temperatures.


Although the glass is melted into small fibers, it’s still very sharp. When coming into contact with this insulation, the tiny fibers can become lodged in your skin, which causes an itchy and sometimes painful sensation. This is why it’s important to wear proper protective gear around insulation in general; a dust mask, safety goggles, and gloves should be worn at all times. Long sleeves and pants, or a protective suit, is also highly recommended in order to cover up completely. 

Batt Versus Blown-In

Fiberglass can be installed in batts or blown-in form. Batts are pre-formed rectangles designed to fill a specific space. While generally installed upright in walls, they are also rolled out in attics or used in floor joists. This is in order to fill a space such as a stud cavity or the pockets between floor joists.

Blown-in fiberglass is a loose fill insulation that fills irregular spaces better. This is more often used in attics to get in small or uneven areas.

Heat Transfer

Fiberglass insulation slows the rate at which heat transfers through a building enclosure. Having a properly insulated building helps prevent heat from escaping or entering, which can overwork your air conditioner in the summer and your heater in the winter. Preventing this aids in regulating temperature and thus your energy bill.


The rate at which insulation slows heat transfer is called Resistance Value, or R-Value.  R-Value is a numerical value for the resistance of heat. The higher that number, the better the resistance. Blow-in fiberglass, has around R-[2.7] per inch of depth; while fiberglass batts have    about R-3 per inch of thickness.

Where its Used

Fiberglass is one of the most cost-efficient insulations on the market. It’s used both in residential and commercial applications. As a less labor-intensive installation, it can be installed quickly with fewer specialized tools, without extensive set up time. It’s the valued choice for improving efficiency and comfort in your home.

Your local Koala Insulation contractor is focused on providing the best insulation for your building. Evaluating your insulation needs, especially for new homeowners and businesses, is important for keeping your building comfortable and energy efficient. Contact your local Koala Insulation expert today to see if cellulose can solve your insulation needs.