Cellulose Vs Fiberglass Insulation: Which Is Best?

Not sure which type of attic insulation is best for your home? We will compare the pros and cons of two of the most popular choices: cellulose and fiberglass insulation.

Not sure which type of attic insulation is best for your home? We will compare the pros and cons of two of the most popular choices: cellulose and fiberglass insulation.

What is the best attic insulation: fiberglass or cellulose? This one is a tough call. Cellulose or fiberglass insulation can save energy bills by decreasing your home's energy consumption.

Both fiberglass and cellulose offer different styles to cater to every attic need. Fiberglass has rolls, batts, and blown-in, while cellulose insulation also has dense-packed, wet-spray, and loose-fill. 

Either type curbs the noise outside your house and comes from recycled materials. Both have health risks to account for. 

In this article, we will factor in the challenges, types, and benefits of fiberglass and cellulose insulation so you can make an informed choice between two of America's most popular insulation. 

What Is Cellulose Insulation?

Cellulose insulation is one of the most widely used types of insulation in America. Attic specialists refer to it as the "greenest insulation" due to the straightforward garbage-to-attic process it goes through. Manufacturers produce cellulose insulation with recycled newspapers, cardboard, denim, and other recycled paper products. Attic specialists even report seeing bits of currency in some of their cellulose insulation bales. 

Homeowners may choose to install dense-packed cellulose, loose-fill cellulose (or blown-in cellulose), and wet-spray cellulose in their attic. People prefer the installation of cellulose insulation because it is made of sustainable materials, and the minimal processing of turning it into insulation is environment-friendly. Manufacturers produce cellulose in electrically driven mills, which release little to no greenhouse gases into our atmosphere.  

What Is Fiberglass Insulation?

Fiberglass is an equally green insulation material. Fiberglass insulation owes its fluffy and shiny appearance to spun recycled glass, reinforced plastic, sand, and other recycled materials.

Homeowners may install fiberglass insulation as fiberglass batts, loose-fill fiberglass, or rolled fiberglass insulation. Homeowners favor fiberglass as its uses go beyond the home; you can sometimes see it on boats. Batt insulation is the easiest to install and can be the perfect weekend project for the DIYer. Overall, fiberglass is a superior fire retardant. 

Pros & Cons Of Cellulose

Pros Of Cellulose Attic Insulation

  • According to the Natural Resources Defense Council, no adverse health effects have been identified with cellulose insulation. It is recognized and categorized as safe as ordinary household dust. However, installing cellulose causes a lot of dust. Certified attic specialists still need to wear proper PPE and do an extensive cleanup.  
  • Cellulose is high-density insulation. That high-density quality translates into exceptional air sealing and excellent sound reduction. 
  • Cellulose insulation can deliver if the certified attic specialist determines that you need insulation up to an R-50 value or 15" thickness. Cellulose insulation ensures that there's no unwanted air leakage in your attic. Cellulose can also be a powerful thermal barrier protecting your attic and living spaces against extreme outside temperatures. 

Cons Of Cellulose Attic Insulation

  • It has a short lifespan of up to 30 years only. Cellulose vs. fiberglass? It's worth noting that cellulose is more expensive than fiberglass attic insulation.  
  • Cellulose is known to cause the ceiling to sag, and it settles over time, leading to lessened R-values. 
  • Cellulose insulation is not for the DIYer. Installation of cellulose requires blowers and pneumatic tools. Cellulose vs. fiberglass blown insulation? Both fiberglass and cellulose installation need a blowing machine to cover irregularly-shaped attics and reach tight spaces, ceilings, and walls. 
  • You would need a vapor barrier with your cellulose insulation, as it isn't moisture-resistant. Absorbing moisture quickly results in water damage and shortens the life span of the cellulose insulation even more.  
  • Cellulose attracts dust and lint more and has low fire resistance. 

Pros & Cons Of Fiberglass

Pros Of Fiberglass Attic Insulation

  • You can reuse fiberglass blown-in insulation by collecting it and transferring it to another area. However, there's not much data if cellulose material holds up well if you relocate it.  
  • Fiberglass insulation material decreases external noise and is outstanding in providing soundproofing, especially when installed in wall cavities.
  • Not only eco-friendly but also DIY-friendly too! Save on labor costs when you DIY install batt or roll fiberglass insulation. 
  • Fiberglass vs. cellulose insulation? Fiberglass has a long lifespan of up to 50 years compared to cellulose insulation. It is low-maintenance, too. You only need to inspect for water damage once in a while. 
  • Cellulose vs. fiberglass insulation cost? Fiberglass insulation is more cost-effective than cellulose. It has an affordable average price of up to $0.50 per square foot of insulation. 
  • Fiberglass generally does not promote mildew and mold and is non-flammable. But as with any other insulation, periodic checks are still a must. 

Cons Of Fiberglass Attic Insulation

  • Breathing in or touching the microscopic glass fibers of fiberglass insulation can irritate the lungs and skin. When handling fiberglass, it's best to don gloves and dust masks. You must also wear pants, long sleeves, and Personal Protective Equipment (PPE). A certified attic specialist would have all the proper protective gear needed. 
  • Another concern with doing-it-yourself is that fiberglass particles could enter the home air supply when homeowners unknowingly leave HVAC ducts lying in the fiberglass loose-fill insulation. Hiring a certified attic specialist ensures that you have all your bases covered.

Installation Process and DIY-Friendly Features

When it comes to the installation process, both cellulose and fiberglass insulation have their unique characteristics. Fiberglass insulation is often praised for its DIY-friendly features. Homeowners can easily handle batt or roll insulation installations on their own, which can save on labor costs. These pre-cut sheets of insulation fit neatly between wall studs and ceiling joists, making it a popular choice for those who prefer a hands-on approach to home improvement.

On the other hand, cellulose insulation typically requires professional installation, as it involves a more complex process. This insulation material is usually blown or sprayed into place, ensuring that every nook and cranny is appropriately covered. While professional installation may come with added costs, it guarantees a thorough and efficient insulation job, leading to better energy efficiency in the long run. So, if you're a dedicated DIY enthusiast, fiberglass might be your preferred choice, but cellulose may be the way to go if you value a comprehensive installation.

Environmental Impact

When it comes to environmental impact, both cellulose and fiberglass insulation have their merits. Cellulose insulation is often lauded for its eco-friendliness. It primarily comprises recycled paper products, making it a sustainable option. Additionally, the manufacturing process of cellulose insulation tends to have a lower carbon footprint than fiberglass.

Fiberglass insulation, on the other hand, is made from sand and recycled glass. While it does involve using non-renewable resources like sand, recycling glass into insulation material is a positive environmental aspect. However, some concerns have been raised about the energy-intensive manufacturing process of fiberglass.

Moisture Resistance and Maintenance

Moisture resistance is crucial when considering insulation materials, as excess moisture can lead to various problems, including mold growth and reduced insulation effectiveness.

Cellulose insulation has decent moisture resistance due to the fire-retardant chemicals added during manufacturing. However, it can still absorb moisture over time, which may compromise its insulation properties. Proper installation and vapor barriers can help mitigate this issue, but periodic checks are essential to ensure longevity and effectiveness.

Fiberglass insulation, on the other hand, is naturally resistant to moisture. It doesn't absorb water, which makes it less susceptible to mold growth or deterioration. However, installing fiberglass insulation with proper ventilation is essential to prevent condensation issues. Like cellulose, regular maintenance and inspections are advisable to confirm that moisture has not affected its performance.

In both cases, maintaining a dry and well-ventilated attic space is crucial to maximize the lifespan and efficiency of your chosen insulation.

Cost Considerations

When deciding between cellulose and fiberglass insulation, cost is a significant factor. Let's break down the cost considerations for each type:

Initial Investment

Fiberglass insulation typically has a lower upfront cost compared to cellulose. This affordability can make it an attractive option for budget-conscious homeowners.

Long-Term Savings

While fiberglass may be cheaper initially, cellulose insulation often provides better long-term energy savings due to its higher R-value (insulating effectiveness). It can reduce heating and cooling bills more effectively, offsetting the initial cost difference over time.

Overall Cost-Effectiveness

The cost-effectiveness of insulation depends on your specific circumstances. If you plan to stay in your home for many years, cellulose may be the more cost-effective choice due to its energy-saving potential. However, fiberglass may be preferable if you're on a tight budget and looking for a more affordable option upfront.

Health and Safety Concerns

Both cellulose and fiberglass insulation have health and safety considerations that homeowners should be aware of:

Fiberglass Insulation

Fiberglass insulation can release tiny airborne glass fibers during installation or when disturbed. Inhalation of these fibers can irritate the skin, eyes, and respiratory system. It's essential to wear proper protective gear, such as gloves, goggles, and a mask when handling fiberglass insulation. Adequate ventilation during installation and avoiding direct contact with the material can reduce health risks.

Cellulose Insulation

Cellulose insulation may contain fire-retardant chemicals such as borate, which can be an irritant if inhaled or if it comes into contact with the skin. When installing cellulose insulation, it's crucial to wear appropriate protective gear, similar to what is recommended for fiberglass. Additionally, take care to avoid inhaling airborne cellulose particles during installation.

To mitigate health risks associated with both types of insulation, it's advisable to hire certified specialists who are trained in proper installation techniques and safety measures. Professionals can ensure that insulation is installed correctly and safely, reducing the risk of exposure to potentially harmful particles.

Special Considerations for Attic Design

Attic design and structure can influence the choice between cellulose and fiberglass insulation.

Proper attic ventilation is essential regardless of the insulation type. Inadequate ventilation can lead to moisture buildup and reduce insulation effectiveness. Fiberglass insulation may be more forgiving in attics with suboptimal ventilation due to its moisture resistance. Cellulose insulation, while effective, requires a well-ventilated attic space to prevent moisture-related issues.

Attic designs may sometimes include irregular spaces or obstacles that make installing either insulation type more challenging. Fiberglass insulation's flexibility allows it to conform to different attic layouts, whereas cellulose insulation may require more effort to ensure complete coverage in complex spaces.

Some attic designs may involve structures or utilities (e.g., HVAC ducts) that could compress insulation when it's installed. Compressed insulation loses its effectiveness, so choosing an insulation type that can accommodate such obstacles is crucial. In many cases, fiberglass insulation is better suited for these scenarios due to its resilience and ability to maintain its insulating properties even when compressed to some extent.

Comparative Lifespan and Durability

Regarding the lifespan and durability of insulation, cellulose and fiberglass offer reliable performance when installed and maintained correctly. Cellulose insulation can have a lengthy lifespan, potentially lasting several decades if it remains dry and free from moisture-related issues. However, it's important to note that cellulose insulation is more susceptible to moisture absorption than fiberglass, which could compromise its longevity. 

Several factors can influence the lifespan of both insulation types, including the quality of installation, moisture control measures, pest prevention efforts, settling over time, and the overall conditions of the attic where they are installed. Regular inspections and adjustments, as needed, can help ensure the durability and effectiveness of either cellulose or fiberglass insulation. When choosing between the two, consider your attic's specific conditions and insulation requirements to make an informed decision that maximizes the insulation's longevity and performance.


Offhand, cellulose insulation comes off as better insulation than fiberglass because of its higher R-values, higher density, lesser warnings on the packaging, and better impact on the environment and health. But take what some other attic professionals might say with a grain of salt. Some might want only to upsell you with the more expensive cellulose insulation, stressing the higher R-value of cellulose vs. fiberglass and the higher density that cellulose insulation offers. 

Remember that R-values are dependent on your home's climate zone, location, and age. You don’t need the full-blown R-50 value when your attic does not require it. In fact, over insulating your attic opens a whole other world of problems.

Unknowingly, compressing insulation loses its R-value, and your attic may not be built for the heavier, denser cellulose insulation. Your home may be more optimal with the lighter fiberglass insulation with an R-38 value.

Blown-in cellulose vs. fiberglass? As for the health risks, you would still need certified attic specialists in full gear to install blown-in cellulose and fiberglass insulation. It's best to take advantage of the wealth of knowledge and ready protective equipment they offer. 

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