Types of Attic Insulation, Their Benefits, and Their Drawbacks

Homeowners understand the importance of attic insulation to keep the house cool in the summer and warm in the winter and the energy bills low. After all, if you’re cranking the A/C to the fullest setting and feel that heat the second it’s switched off, your system is going to be working harder and will be running longer and leading to more wear and tear on your HVAC system, higher utility bills! You know it's important, but do you know what types of attic insulation are available their benefits, and their drawbacks? Are you aware that homes in the greater Phoenix area should have a minimum of R-38 Value insulation in their attic?  

This article outlines everything you need to know about the most common types of attic insulation. We’ll uncover what makes them a good choice, but also shine a light on potential problems each may present. By the end of this article, you’ll be able to make an informed decision about which type of attic insulation you want to install in your home.

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Without a doubt, Blown-in Cellulose Insulation is the most commonly used attic insulation type in Arizona Homes. The insulation blown in for this type is cellulose. Cellulose is created with recycled materials, like newspaper, cardboard, and other wood-based materials. Boric acid for pest control, and ammonium sulfate and borate as a fire retardant are added for fire-proofing, and it’s then blown out to fill the space.

The Advantages of Blown-In Cellulose Insulation

Is blown-in cellulose the best type of attic insulation? Here’s what it can do for you:

  • For the most part, blown-in cellulose is kinder to the environment. Cellulose is formed from recycled material, which is far better than creating it from scratch for the planet.
  • Treated to pests and fire retardants that can help reduce the likelihood of a fire or slow down flames.
  • Statistically, the R-Value is better than that of fiberglass batts by 23%.
  • This method fills gaps well, blocking air spaces around any awkward corners, pipes, or cracks.
  • Cellulose is great at battling wind-washing.

The Disadvantages of Blown-In Cellulose Insulation

What are the cons of using blown-in cellulose as your attic insulation? The drawbacks are:

  • Cellulose is eco-friendly, yes, but the substances that are added are not. Boron, which is needed to then create boric acid, is in very short supply. In fact, there are only 3 mines that produce it. This production is causing harm to the earth.
  • This can be a messy process. With batt insulation, it’s all laid out in neat rolls. However, the blown-in method can be messy.
  • Cellulose insulation and moisture aren’t a good mix. If moist, it can spread damp and produce mold.
  • If ammonium sulfate gets wet or thermally decomposes, it can produce sulfuric acid, which is corrosive to metals.
  • Although cellulose is treated with fire retardants, the low combustibility temperatures of cellulose mean that cellulose can smolder for a long time before a fire is discovered.
  • Cellulose breaks down and settles over time, typically settling by 20% after installation. 




Fiberglass batt insulation is the most commonly used insulation type for walls, attics in older homes, or homes with flat roofs. Fiberglass is formed from tiny glass fibers. Before they were turned into glass, they were originally sand and other recycled material.

These little glass fibers are then molded into batts. These are big, rolled-up sheets, which are stuck together with the help of a vapor barrier, which glues them together. This is usually performed with reflective paper or foil backing.

The Advantages of Fiberglass Batt Insulation

So, what are the advantages of choosing fiberglass batt insulation for your attic insulation?

  • Firstly, fiberglass batt insulation is, for the most part, kind to the planet. Bearing in mind that the fiberglass itself is made from sand and recycled material, it is classed as a form of renewable energy. When you switch on the heating, you’ll do so guilt-free, as your insulation contributes toward a greener planet.
  • This method of attic insulation has been treated with fire-proofing material, which is reassuring to homeowners.
  • Due to the air pockets that form during installation, fiberglass batt insulation doesn’t collapse or shrink easily.
  • The installation process is easy. Many homeowners elect a DIY job rather than paying for a professional fitting.
  • Fiberglass is a great barrier to sound. While it’s installed to keep your home comfortable, it’s an added bonus that it traps loud noises and keeps your neighbors happy.

The Disadvantages of Fiberglass Batt Insulation

As stated, fiberglass batt insulation is the most commonly used insulation type for walls, attics in older homes, or homes with flat roofs. That said, there are some disadvantages to fiberglass batt insulation that you should know about:

  • Fiberglass can cause safety concerns. Remember, fiberglass is formed out of hundreds of tiny, thin, slivers of glass. So, it can be dangerous, if you come in contact with it.
  • Adding to the safety element, the vapor used does help fireproof the insulation, but there is still a risk. This vapor also can be dangerous should it be inhaled or touched. You’ll need to wear gloves and masks if you choose to install fiberglass batt insulation yourself.
  • You’ll need a minimum thickness of 10" (on average) to have sustainable insulation value.
  • Can contain formaldehyde


You only need to hear the words "attic insulation" to start picturing fluffy pink or yellow clouds. Blown-in Fiberglass Insulation has come a long way from its inception. Years ago, fiberglass was extremely hazardous in the sense that the fibers were not really fibers but more like slivers of glass (essentially just chopped up batt insulation). If you came in contact with it, you would be itching for days!

The production of fiberglass remains the same, however, it has been refined dramatically for blown-in insulation. It still uses sand and recycled glass which is extruded into a spinner (like cotton candy) to make fiberglass wool. Similar to Cellulose, it is "blown-in" using a special machine, however, that is where the similarities end. Rather than using recycled paper and cardboard that is treated with chemical agents to inhibit pests or prevent the spread of fire, Fiberglass Wool is naturally: Mold, Pest resistant, and Non-Flammable, what's more, is that it does not absorb moisture. 

The Advantages of Blown-In Fiberglass Insulation

Is blown-in fiberglass insulation worth your money and time? Here are the benefits of blown-in fiberglass insulation:

  • Energy efficiency increases. Blow-in fiberglass wool insulation is great at keeping your home cool in the summer and warm in the winter, 
  • this means that your HVAC system will not run nearly as much.
  • It fills more cracks, bridging the gaps where air would usually seep through.
  • Blown-in fiberglass wool insulation also traps noise.
  • This insulation doesn’t use any chemicals or additives, helping to improve your Indoor Air Quality circulating in your home.
  • If installed properly, Fiberglass wool, such as Owens Corning L77 does not settle or break down.
  • Brands like Owens Corning is Green Guard Certified, and are validated to be Formaldehyde free. 

The Disadvantages of Blown-In Fiberglass Insulation

We know what’s great about blown-in fiberglass insulation, but what about the not-so-great parts?

  • Because it is made of glass, Blown-in Fiberglass wool does not absorb moisture, however, it does not repel it either. 
  • If you have a plumbing or roof leak, you will most likely have to remove the affected area and replace it with new insulation.
  • If it is not installed properly, Fiberglass wool will settle and have reduced performance. 
  • Recessed lighting must be IC rated or have a special Cover installed to prevent overheating.
  • Not all Blown-In Fiberglass wool is the same, some fiberglass wool insulation can settle over time.
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In 2022, it seems that spray foam insulation is growing in demand and popularity. Unlike the other types of attic insulation on our list, spray foam insulation is the only type that comes in liquid form.

Once it’s been sprayed out, it fills the space and grows to the required thickness, then evolves into a rigid foam. This then blocks any draughts or holes where heat could be escaping.

The Advantages of Spray Foam Insulation

So, is spray foam insulation a good attic insulator? Here’s what we love about spray foam insulation:

  • Spray foam insulation has proven to be high-performing in both the short term and long term.
  • The R-Value per inch is high, ranging between 5.6 and 8.0
  • The foam can support and add structural strength to your home.
  • It’s superbly energy efficient.
  • No vapor barrier is required, reducing harmful chemicals.
  • The foam seals gaps and cracks well, filling awkward spaces.

The Disadvantages of Spray Foam Insulation

Spray foam insulation is growing in popularity. However, there are some disadvantages to spray foam insulation that you should consider:  

  • The initial cost is much higher than the other types of attic insulation. However, bear in mind that this cost will balance itself out due to high-performing energy efficiency.
  • Foam Insulation is intended to seal a residence and can significantly decrease air exchanges, emissions from SPF, and other products, including combustion sources, can build up in homes.
  • Additional costs to modify your home to ensure healthy Indoor Air Quality as well as adequate ventilation.
  • If cavities are missed when the foam is installed, it can create (or add to) water damage.
  • As this is a large potential problem, it’s advised to have a professional install your spray foam attic insulation. 
  • The foam consists of a mixture of chemicals that are dangerous if inhaled or touched, requiring you to vacate your home for an extended period of time to allow it to "air out". 

5. Sealing Attic Air Leaks Helps Save Energy and Money, as well as keep your home cooler and safer from harmful airborne particulates and pests.

One thing that is often overlooked is Air Infiltration. Did you know that up to 40% of the air leakage in your home can be through the attic floor? 

If your heating and cooling costs are going through the roof (no pun intended), then air sealing the attic floor and adding attic insulation can help cut heating and cooling bills by up to 15%.

Adding more insulation product to a drafty attic space won’t do much good if you don’t identify and seal up air leaks first.

The air inside our homes typically contains a lot of moisture. Excessive moisture in the attic causes trouble. Sealing around cracks and joints to prevent moist air from escaping into the attic.  Air leaks typically happen around dropped soffits, through recessed lighting, electrical boxes, and at intersections of floors/ceilings and walls. Not only does sealing these areas prevent moisture from entering your attic, but It also helps prevent unwanted pests from getting in through those cracks, as well as preventing harmful airborne particulates from entering your home.

Living in Arizona with hot summers, you know the challenges of keeping your home at a comfortable temperature without your air conditioning costs going through the roof. When it comes to outdoor heat, Air Sealing keeps hot attic air infiltration at bay, and attic insulation helps to stabilize indoor temperatures and keep air-conditioning costs more reasonable. 

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Get in touch with our Insulation experts and stay comfortable in your home.

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