Can Fiberglass Insulation Be Blown In? (Helpful Guide)

Fiberglass is the fluffy, lightly-colored material that you find in your walls. When properly installed, fiberglass has the ability to reduce the amount of heat, moisture, or sound that moves through the walls. But how does it get in there?

Fiberglass insulation can be blown in walls, as this is one of the primary methods of installing fiberglass. Loose fiberglass is small enough to be packed tightly into wall columns or sprayed on the floor, resulting in small-to-no air spaces.

If you’re looking into blowing some fresh fiberglass into your home’s structure, here’s what you should know.

What Is Blown In Fiberglass Insulation?

Simply put, blown-in fiberglass insulation is the process of using an industrial machine called a “hopper” to “blow in” fiberglass material.

Imagine using a giant water hose to spray shredded pieces of soft material all over your attic or basement floor…that’s blown in fiberglass insulation.

You may think of the long sheets of pink foam that you see many carpenters or roofers use while working on a house. The bundles are known as “batts’ ‘ and they’re used in faced fiberglass insulation considering a kraft paper is attached to it as a security against vapor.

However, by using the hopper, churned material creates more space for clean air to move through with less worry of heat and excessive moisture that causes mold.

Fiberglass materials that are used in blown-in insulation are rated based on their R-value, with the “R” standing for “resistance”. The R-value determines how well the insulation material can resist heat and other forms of unnecessary conditions.

You can relate R-value to temperature and how well the material can withstand it. The thermal resistance is measured in “per inch”, and the higher the R-value, the greater the insulation.

Different Types of Blown-In Insulation

Various forms of blown-in insulation mainly include cellulose and loose-fill fiberglass. Other organic materials like cotton, wool, foam, and rocks can be used based on their R-value.


One of the most popular choices is cellulose blown-in insulation because of its ingredients: recycled newsprint and other forms of paper! This makes cellulose safe for us humans to operate with, while also saving the planet by using reused material.

There’s only one issue with cellulose, and that is the chemicals used on them. Paper is prone to excessive moisture and can cause mildew, so chemicals like ammonium sulfate, formaldehyde, and borate are used to keep it intact.

Luckily, dried cellulose is available, making it safe once again. Its R-value is 3.4 per inch, making it a sure choice for quality insulation.

Loose-fill Fiberglass

Loose-fill fiberglass insulation is made from glass and sand, then spun into fibers. This type of insulation is best suited for preventing ample amounts of water from forming, leading to fungi and mold.

Including sand and glass, manufacturers may join the eco-friendly movement and include about one-third of recycled material into their fiberglass.

A move like this makes the fiberglass non-flammable, resistant to bugs and rotting, with an average R-value of 3 per inch. Loose fill is voted to be one of the best blown-in insulation for filling tight holes and pipes.

Spray Foam

Blown-in foam insulation is better known as “spray foam insulation”, and has a high R-value rating of 3.8 by thickness. Open-cell spray foam leaves a few more air pockets, allowing for smoother passage, thus faster air.

On the other hand, closed-cell spray foam has much tighter passage ways, leading to less heat and moisture. This feature provides for an insulation of R-7 per inch!

Organic Materials

Rock wool (also known as mineral wool) is a solid runner up to the top two modern choices. Similar to fiberglass, rocks and minerals are matched with wool and spun into a fiber like cotton candy.

Contrary to popular belief, rockwool does very well with insulating walls due to its 3.1 R-value. Cotton can match it at R-3.5, and even has a lesser risk of being a safety hazard because of its renewable resources.

Is Blown In Fiberglass Insulation Good?

Blown in fiberglass insulation has been deemed a great investment for homeowners, like you, who care about the quality of the air in your house. The major feature of what makes blown-in a solid choice is that it’s eco-friendly amongst other advantages.

For starters, recycled pieces of organic material are used in the hopper, so you know that what you’re breathing is safe. Sure, chemicals and by themselves, they are harmful to inhale or have direct contact with.

But because of the treatment process that it goes through, the chosen shreds will be capable of securing your home from foul air without negatively impacting you.

Additionally, because of the highly successful rate of packing shreds, blown-in insulation has been known to significantly reduce a home’s electricity bill over time.

How? Because of the pack loose-fitted fibers, cool air can be pushed through much easier, making your air conditioning and other appliances work more efficiently and saving you cash money.

Benefits of Blown-In Insulation

When considering benefits, you should know that blown-in insulation is way faster! The average time of unrolling and laying down blankets of fiberglass on your attic floor or walls can equal up to days of work.

On the other hand, with a hopper, you can install fluffy pieces of fiberglass all over the floor and in the walls in one to two hours! Blowers can be a bit pricey, but are worth the value of the time you’ll end up saving.

Let’s also add that blown-in insulation allows you to customize the tightness of the fiberglass based on the range of R-value you desire. By using the hopper, you can start, stop, add, and subtract the amount of material to ensure proper hold for effective air flow.

For those who like to partake in green products, cellulose would be a great choice. By choosing cellulose for insulation, more paper, plant-based products, and wood are used, which encourages recycling!

Blown-In Insulation for Walls, Attics, and Basements

When installing blown-in material for walls, ensure that the material is shredded well enough to fit securely around the interior drywall. The fiberglass – or chosen option – will fill and pack as you easily spray it until filled.

Attics are the easiest as it simply consists of you spraying the insulation onto the floor and creating a bed of fiberglass on and in between the floorboards for efficient moisture and heat absorption.

Basements are the same concept as the attic and wall. The fiberglass can be shot onto the floor, stuffed into awkward spaces, also packed into pipe and wall crevices.


We now know that fiberglass insulation can be blown in, with many advantages. Fiberglass has a great resistance level to create clean air flowing throughout your home, with little-to-no concerns towards negatively impacting your health.

Alongside cellulose, rock wool, and other organic materials, blown-in insulation has the ability to promote effectiveness that leads to saving money and having a healthy home inside and out.

You Might Also Like:

About The Author

Scroll to Top