Need to pick between the two and don’t know what’s best for your home? Read our comprehensive guide to get your answer.
“So what is better, fiberglass or cellulose?”
We hear this question a lot! To give you an answer, once and for all, we gathered everything you need to know in one place.
In the days before stricter building codes and safety regulations, builders and homeowners could take their pick from a number of insulation materials: Mineral-Wool, Rock-wool, Fiberglass, Vermiculite, Cellulose and more. As time went on, the options narrowed as one or the other insulation material was found to be impractical, ineffective or just plain dangerous. There now two insulation materials to choose from: Cellulose and Fiberglass. Where the confusion begins is that Cellulose is available only in blown material form while Fiberglass can be found in both blown or rolled batting forms. All it takes is a little research to find out which of the two is the better insulation material for your needs.
Fiberglass VS Cellulose
Fiberglass Insulation Material
❏ Come with No Guarantee
❏ Has a Hazard-warning
❏ Known for being irritating and itchy
❏ Shows no resistance to insects
❏ Needs at least 12” for R-30
❏ Glass fibers are rigid
❏ Will barely melt in a fire
❏ No resistance to mildew or mold
❏ Minimum possible soundproofing
❏ Rodents tend to nest in Fiberglass
Fiberglass is found on the market in two forms – either as blown (loose-fill) or rolled (batting) material. Initially most homeowners feel that they want to order rolled insulation but after some research find that they prefer something else. In blown or rolled form, Fiberglass insulation has a number of negative points that impact the safety and health of homeowners and their families. It is vital to conduct your own research before choosing to use Fiberglass for your home!
Fiberglass is made up of miniscule, sharp and rigid glass fibers. Due to this property, all fiberglass products come with a hazard label that warns of an increased risk of upper respiratory irritation or illness, cancer or other similar conditions. Ask anyone who has worked with Fiberglass in the past and they will mention how it results in an irritating ‘itch’. Laborers and contractors avoid working with fiberglass or charge more to work in an attic that contains fiberglass.
Homeowners mistakenly think their attic area is separate from their primary living spaces. The surge in the use of HVAC units, recessed lighting fixtures and the presence of other devices in the attic has led to an increased amount of air flow between the living spaces and the attic area above. In the cases that a home is traced as a cause for the occupant’s health concerns, representatives from environmental companies first strip the Fiberglass insulation from the attic. If nothing else, they quickly cover Fiberglass with Cellulose insulation to seal and trap the harmful vapors.
Unlike Cellulose, Fiberglass does not carry a lifetime guarantee. After installation, blown fiberglass has been reported to pack and settle. While it resembles cotton-candy during the installation process that fluffs it up, blown Fiberglass product begins to constrict and settle as time goes one. To avoid fluffing, installers can choose to go with rolled Fiberglass, however the application of rolled fiberglass does not seal the top of framing and provides uneven coverage around piping, conduits and plumbing the attic area. So while rolled Fiberglass will not settle like blown Fiberglass, it provides inadequate fit and coverage in general.
When compared to Cellulose, Fiberglass is the less cost-effective and inferior product. It takes Fiberglass of 12” thickness or above to secure an R-30 rating while Cellulose material only requires the thickness to be 8.1” to gain the same R-30 rating. An experienced contractor will agree that working with itchy, 1 foot-thick Fiberglass is tougher than dealing with 8” of softer Cellulose material!
Rather than resist termites or insects, fiberglass invites pests, rodents and vermin to feel at home. We often come across proof that mice and rats have been living in pre-installed Fiberglass material. All it takes is a little moisture for mildew and mold to develop. Cellulose material, in comparison is completely resistant to rodents, insects, fungus, mold and mildew.
Cellulose Insulation Material
❏ Itch-free insulation material
❏ Comes with a lifetime guarantee
❏ Resists rodents
❏ Resists insects
❏ Safe and non-toxic
❏ Resists both mildew and mold
❏ Needs just 8.1” to achieve an R-30
❏ Provides soundproofing
❏ Soft material for insulation
❏ Completely non-flammable
Cellulose, unlike Fiberglass material, is available only in form as a blown (loose-fill) material. It is considered the safest, longest-lasting, most efficient and most effective material that can be used for insulation purposes. Out of the many advantages Cellulose has over Fiberglass is that it comes with a lifetime guarantee and is resistant to mold & mildew, insects and rodents. Cellulose is designed to be non-flammable in all hazardous conditions. Cellulose does not cause itching and provides adequate soundproofing qualities as a bonus. Perhaps the most winning aspect of Cellulose is how it is non-toxic, environmentally-friendly and safe for use.
Other advantages that Cellulose has over Fiberglass includes that it can attain an R-30 rating with just 8.1 inches of thickness while Fiberglass requires the thickness to be 12 inches before resulting in a similar performance. This makes Cellulose the more prudent and cost-effective material to use. Cellulose comes without any hazard warnings, unlike fiberglass. Every single piece of Cellulose undergoes rigorous testing before getting approval by OSHA, the Underwriters Laboratories (UL label) and the Consumer Products Safety Commission.
Cellulose material is comprised of repurposed wood fiber product, which consists of cardboard, newspaper and other wood-type products. Despite it being made up of reconstituted wood, cellulose is not flammable because of the borate treatment it receives to make it permanently non-flammable. Cellulose meets all specifications set by local, state and federal building authorities and holds an ASTM Class 1 rating for being non-flammable insulation material. If you are in the mood for an experiment, hold up a match to the Cellulose product and watch how it will not burn!
In addition to becoming permanently non-flammable, another benefit of a borate treatment is that Cellulose material becomes completely resistant to rodents, mildew, mold, fungus and insects. Cellulose is environmentally-friendly as it is mostly made up of recycled materials. Cellulose also manages to reduce sounds from surrounding rooms; most homeowners observe a much calmer, quieter home after the installation of Cellulose insulation. Read up more about cellulose at the following websites: www.cellulose.org, www.greenfiber.com, www.ornl.gov – Department of Energy.
Blown-in Vs. Rolls (Batting)
Batts or rolls made of Fiberglass provide utility since they can be installed under floors or used for open-framing situations or at brand-new construction sites. However, when a home is already built, fiberglass can either be blown with loose-fill (cellulose or fiberglass) material or rolled with batting. A blown application provides more benefits over batting application.
Most homeowners work with the assumption that batting is superior since it seems like a neater insulation job. Others are either recommended to think this way due to their contractor or they are just familiar with the rolled form. Rolled fiberglass is installed, in most situations, only because it is more convenient to do so during construction. If anyone takes the time out to do some research, it is easy to see that blown Cellulose would be a better choice.
One major disadvantage is how rolled material must be installed between every single ceiling joint, with it being fitted loosely at some points and tightly at others. Rolled material must be fitted around many oddly shaped nooks and corners due to electrical conduits, piping and plumbing in the attic space. Rolled application results in voids and other ‘leaks’ that compromise the overall performance of the insulation. For a tighter, blanket-type insulation, homeowners should opt for blown application or “monolithic fill”. “Monolithic Fill” stands for blown material that is applied in a way that it seals and covers everything in that space like a blanket.
Research at the University of Colorado has concluded that R-30 batting is rivaled in performance by blown-in insulation rated at R-19. Flipping this over, R-30 batting is only matches R-19 when it comes to practicality. Rolled material may be stamped as R-30 but it delivers a performance of R-19.
Attics with existing or old insulation will not work well with rolled material as it leaves gaps and results in a compromised fit. This is the reason why only homes lacking insulation are chosen to be fitted with rolled fiberglass. Removing or vacuuming-out old insulation is an impractical, expensive and time-consuming task. It is better to stack more material on top and bring the attic’s performance up to R-38 or R-30.
Since blowing insulation allows installers to “shoot” material up to a distance of 20 feet, they can reach those hard-to-reach spots. Not every inch of the attic needs to be worked upon, so this reduces the chance of disrupting wiring or placing considerable burden upon ceiling framing that may crack under the installers’ weight. Blown material covers the entire attic floor and reaches into the deepest corners with ease.
Blowing insulation allows installers to use cellulose instead of fiberglass for the insulation task. Fiberglass is beaten by Cellulose as it is longer-lasting, safer and more cost-effective. Do refer to our materials comparison breakdown for further details.
Fiberglass Vs. Cellulose Studies by the University of Colorado
University of Colorado’s School of Architecture and Planning conducted a two-month study that compared two test buildings for their efficiency in energy conservation.
One building had cellulose insulation while the second one had fiberglass insulation in the attic and walls.
The study’s outcome was:
Cellulose reduced air infiltration more than 30% and created a better sealed building cavity than Fiberglass. When the heat was off at night-time for 9 hours, the building with cellulose retained 7 more degrees of heat compared to the building with fiberglass. They estimated that that the cellulose insulated building would require 26% energy to heat sufficiently compared to the building insulated with fiberglass. They also realized that in more severe temperature climates, the energy benefits would be greater with cellulose insulation. Cellulose blown-in insulation led to a reduction of air leakage better than fiberglass blown-in or batting insulation. The research study concluded that cellulose insulation was the superior product as it requires less energy to heat or cool homes than Fiberglass.
The Fake News of Insulation
So many homeowners I have had conversations with over the years say they do not want “the blown-in” materials for insulation. The thing to remember is not all blown insulation works the same way. Usually plumbers, contractors or electricians will recommend that homeowners avoid fiberglass in blown form as it is extremely itchy and tough to use. They misrepresent blown insulation when they are simply talking about blown Fiberglass insulation, and not Cellulose. Cellulose does not itch, in fact it is soft material that is easy to work with.
The other reason homeowners avoid blown insulation is that they had it in their previous homes. They confuse blown fiberglass for blown cellulose insulation. While cellulose will also settle down, it will do to a lesser degree than blown fiberglass and carries a lifetime warranty to retain its insulating qualities.
So Why Do Insulation Companies Still Use Fiberglass?
1. One of the main reasons insulation companies still use fiberglass as insulation material is that their primary work is with new construction projects that have requirements for rolled fiberglass. Insulation companies promote and use fiberglass as much as possible because the more fiberglass product they use, the better and more affordable their purchasing tier becomes.
2. Unlike Cellulose, blown fiberglass material can be fluffed up and provides extensive coverage. For those insulation companies who can convince their customers it is a solid product, they tend to make a bigger profit. In other cases, they can offer a lower quote than their competitor to secure a job.
3. Most insulation companies do not possess the costly equipment for regular installation, like a truck and insulation blowing machine, so they choose to promote rolled Fiberglass instead.
4. The fact that most homeowners shopping for insulation are already familiar with Fiberglass helps insulation companies sell it. Homeowners have most likely seen it being installed at new construction sites or on the shelves at a local home improvement store.
To be perfectly fair, there are scenarios where using Fiberglass is the practical choice, such as when there is open-framing to be done, to wire it under floors, on top of vertical knee-wall sections in attics and for use during the construction of a new house. Keeping in step with contemporary trends in building and construction, Cellulose insulation’s popularity is due to it being a superior product- it is longer-lasting, safer, more effective and more efficient than any other insulation material.
In conclusion: in most cases cellulose blown-in insulation is the superior choice, however fiberglass batt insulation is a suitable candidate for replacing cellulose when required. It is to be said that both materials are far superior to the inferior blown-in fiberglass insulation material.