Cellulose v/s Fiberglass Insulation. What’s best for you?

cellulose vs fiberglass insulation

Fact Check: About 50% to 70% of the energy is consumed for heating and cooling in average homes.

Insulation is one of the best ways to reduce and control your energy bills from peaking. The even-more-important-factor is its function of maintaining and providing an even thermal condition in your home or commercial structure. As compared to older homes, newer homes cost you lesser energy bills. Basically, insulated homes perform well and increase their comfort level. There are different types of insulation with their respective specifications, pros and cons. This article is going to discuss on Cellulose Insulations vs Fiberglass Insulation, since it’s most commonly used and have higher demands in the building industry. 

Cellulose Vs Fiberglass Insulation

Both cellulose and fiberglass are two most commonly used insulations. The two insulations have successfully improved energy efficiency in homes over the years. With varying locations and building code requirements, fiberglass and cellulose insulation can be beneficial for homeowners, builders and remodelers.

There are existing actors that distinguish these insulations from each other. Although fiberglass precedes and has been frequently used, cellulose insulation has been gaining more popularity in recent times. 

What is the difference between Cellulose and Fiberglass?

 As homeowners, it is necessary to know about the insulation being used in your homes for its enhancement in terms of safety and comfort. Before knowing which insulation is better than the other and why, understand what these insulations are made of and how they are used. 

John Meeks Explains Cellulose vs. Fiberglass (published by https://www.youtube.com/user/divb/featured)

What is Cellulose insulation?

Cellulose Insulation also called as the greenest of the green is 85% recycled paper, 25% treated with non-toxic borate compounds that prevent mold growth or insects and fire and is high in thermal efficiency.

Cellulose is a wet-spray or loose-fill form of home insulation which is used in enclosed existing walls or open new walls and attic floors. It is ‘green’ which means greater per cent of its composition is recycled and environment-friendly. According to the claims of Cellulose Insulation Manufacturers Association Canada (CIMAC), insulating homes with cellulose recycles newspapers compared to an individual’s consumption in 40 years. Often made using paper fibers, newsprint, cardboard are the primary ingredients. Cellulose Insulation is considered as a natural thermal insulation that increases the efficiency of structures it is used in.

What is Fiberglass Insulation?

30% to 50% of the raw material used in the manufacturing of fiberglass comprises of the recycled window, bottle or automotive glass. 

Since 1938, fiberglass has been preeminent insulation material for many homes and other commercial buildings. Fiberglass insulation is an amalgamation of limestone, soda ash, silica sand, and recycled glass cullet. In simple words, it is made of glass fibers. Micro-thin glass fibers spun into batts make structures more energy-efficient and reduce utility bills making the structure more comfortable for the occupant. Newly manufactured fiberglass is higher in R-value as compared to the older ones. Fiberglass insulation can be installed in unfinished walls, ceilings and floors and fitted between joints, beams and studs. Fiberglass comes in different types- batts, rolls and blown-in insulation.

Batts are usually placed between frames and used in walls, floors, attics and ceiling. Rolls are fitted between joists and studs. Blown-in fiberglass is used for wall cavities and attics. 

What are the benefits of Fiberglass and Cellulose Insulation?

Cellulose Insulation Fiberglass Insulation
It is ‘green’ or eco-friendly.  Lightweight and easily portable. 
Fills cavities and creates an energy-efficient building.  High thermal performance and available in different types.
Retains its R-value even in extreme cold conditions.  Easy for DIY installation and cost-effective
Health-friendly, fireproof, resists mold. Fireproof 
No degradation concerns. Prevents mold or mildew growth.
Soundproof Soundproof
Repels insects and critters Similar to animal bedding (higher risk of animal infestation)

Is Cellulose Better Than Fiberglass?


The light weight and flexibility of fiberglass make the installation easy. Along with that, transportation and application become simple and easier too. While cellulose is 18% heavier and requires adequate installation knowledge or improper installation leads to the reduction and degradation of thermal protection. Fiberglass is less dusty and easy to handle. Cellulose is comparatively dustier due to its recycled component and requires a minimum of 36 hours to dry. With its ability of high compressibility and lesser chances of degrading the effectiveness of R-value, fiberglass can be manufactured into greater amounts. Fiberglass batts are easier for installation, especially for DIYers. But it needs to be blown-in with a blowing machine which is slightly more difficult and may require professional help. Cellulose insulation is more commonly installed by professionals and is always blown-in. 

Video on Why Cellulose Insulation is Better than Fiberglass Insulation (published by Dr. Energy Saver)

Thermal Performance

As a known fact, R-value or thermal performance determines the efficiency of insulation. While both fiberglass and cellulose contain similar R-values, it depends on where and how they are installed. Proper installation in similar areas pushes both insulations at about the same R-value. Cellulose has R-value of 3.2 to 3.8 per square inch approximately, while fiberglass has R-value of 2.2 to 2.7 per square inch approximately. However, it is not necessary to always choose the insulation with a higher thermal performance.

According to the Oak Ridge National Lab, fiberglass loses 50% of its R-value in extreme cold conditions and cellulose make a better choice for homes located in colder regions.

Consideration must be made in terms of building code and requirements of the home or other structures. Installing both insulations, loosely or densely, R-value changes with it. In extremely cold conditions, fiberglass insulation tends to lose its R-value which may also be common with cellulose. With the selection of R-value, it is better to have a professional suggestion alongside. 

Air Leakage

NEITHER of these two insulations is air barriers. For fiberglass, air circulation is its innate feature or properties. Whereas cellulose insulation can decelerate the air flow in the walls. Densely packed cellulose into cavities can prevent some air flow.


As fiberglass is made of micro-thin glass fibers, there are fewer or no chances of it burning. Although glass can melt under direct fire or flame, fiberglass insulation is non-flammable as even considered by many studies. On the contrary, as cellulose is recycled paper, it is more flammable. There are chances of cellulose insulation catching fire under extreme conditions or fire accidents. 


Fiberglass blown-in insulation benefits equally or higher STC (Sound Transmission Class) ratings as compared to cellulose products.

In terms of sound control, both fiberglass and cellulose insulation work effectively. Fiberglass absorbs sound and reduces noise. Cellulose insulation prevents transmission of sound through walls or between floors, mostly the density of cellulose benefits here. Both insulating materials have higher levels of soundproofing properties that become a barrier between interior rooms preventing noises from outside sources. 

Health and Environment Concerns

A study in 1994 had classified fiberglass as a potential cancer-causing material but declared not being a health risk to homeowners. 

The very reason for fiberglass insulation being a risk is only when disturbed as it becomes airborne. Undisturbed fiberglass insulation is of no harm. Mostly during installation, there are chances of fiberglass being disturbed. It takes safety precautions before dealing with this insulation. Remember to contact a professional team or contractors for installation to save yourself from potential risks. There is no harm or threat after proper installation of fiberglass insulation. So there is no need to worry or panic for those homeowners who have it installed or considering it. Cellulose insulation is free of risks due its properties and components.

Cellulose is an eco-friendly type of insulation and is considered a green material more than fiberglass. During the manufacturing, cellulose does not pollute the air while fiberglass becomes more airborne polluting the air. Fiberglass is 50% less than cellulose in terms of recycled content and consumes more energy than cellulose. By looking at these factors, it is understandable that cellulose is more environmentally friendly and has no environment risks. It is more suitable for eco-friendly modern homes and homeowners who are concerned about environment.

Which Insulation Is More Durable- Fiberglass or Cellulose?

Fiberglass has potentially more durability as it does not rot or decay with time. However, it loses its thermal efficiency if worn out over time. It compresses and loses some air pockets if exposed to excessive moisture. This can be a setback to its durability. Cellulose insulation has a similar issue- when exposed to moisture for a prolonged period, it may lose its efficiency. 

Is Fiber-glass cheaper than Cellulose?

Cellulose tends to be more expensive than fiberglass. But the catch here is that it varies with your insulation contractor. While fiberglass insulation has been the choice of many homeowners for years, cellulose is becoming more popular and preferred by homeowners willing to spend for its specifications. Both insulations, however, are more or less the same cost. In addition to that, insulation installation services, brand, and other associated installation fees. 

Is Fiberglass safer than Cellulose?

When it comes to safety, cellulose insulation is safer. Many professionals and studies have found cellulose safer than fiberglass. Comparatively, a cellulose fiber are tightly packed and effectively chokes the wall cavities. This prevents combustion or spreading of fire through framing cavities. 

Which Insulation Withstands Extreme Climate Conditions Better?

Fiberglass loses 50% of its R-value under about 20º F  outside temperature.

Both fiberglass and cellulose have similar reactions under normal temperature fluctuations. Fiberglass differs in this case due to the extreme difference in the interior and exterior temperature. Cellulose has more withstanding power and does not lose its R-value even in extreme cold conditions and this makes it better for homes located in cold climate regions. 

What To Choose?

You can choose either of the insulations considering your location, building code, climate, areas of your home that require insulation. For some, cellulose would work better despite the cost and for some fiberglass would work the best despite its inefficiency in extreme cold. Ultimately, the best advice is to consult a professional team that can inspect your home and guide better accordingly. Insulation installation may look easy for a DIY and for some it could turn out to be, but considering safety measures, it is better handed over to the professionals insulation removal and installation experts. Experts of this industry and area can have better solutions for your problems. It can save yourself from mishaps, improper or inadequate insulation and can give you the right R-value, right insulation for the required areas of your home and make it better than making it worse. 

cellulose vs fiberglass insulation
higher r value means higher effiency
why to insulate your wall
why insulate your home?

Why Insulate Your Home?

how to remove mold
attic rafter ventilation
cellulose vs fiberglass insulation