Cellulose vs. Fiberglass Insulation

Wednesday, February 27, 2013 10:01:00 AM Categories: Energy Savings Green Living Home Maintenance

Insulation is the key to efficiently heat and cool your home. Done properly, insulation will return dividends when the weather outside is frightful. As with all steps of construction, there are several decisions to make before insulating. These decisions can range from types, locations and amounts of insulation. To help you choose, we’ll be going over the differences between the two most common insulations used in homes today, cellulose and fiberglass insulation.


Cellulose vs Fiberglass Insulation






~$0.72 /ft2

~$1.04 / ft2

Approximate R-value




Holds Water

Skin Irritant

Extra Materials Needed



Common Installation




Recycled Newspaper

Recycled Glass

What is it?

The term cellulose actually refers to the sugar compound that makes up the walls of plant material. The insulation associated with cellulose is made from recycled newspaper, and as paper is made from plant material the insulation is referred to as cellulose. The material is then chemically treated to make it fire retardant as well as resistant to molds and mildews. Cellulose is considered a ‘green’ product since it is made from 1) recycled newspaper (approximately 80%) and 2) it requires less energy to make than fiberglass.

How is it installed?

Since cellulose insulation is a loose material it is either blown-in or, in some applications, sprayed-in as a wet mixture. Because it is loose and must be either blown-in or sprayed-in special equipment must be used to install it. The price for a blower can vary but will cost you somewhere in the neighborhood of $75+ a day. The process itself is a little less labor intensive than fiberglass batting in that you need to unroll, cut and in some cases staple in. All you have to do is, more or less, point and fire away. You will need to either stop and fill the blower up or have someone else top it off occasionally. Because of this easy process it is often used to add insulation in attics where you may have to stoop or crawl to get to areas. It is also a great way to add extra insulation in the attic if the current insulation level is lacking.

What is cellulose's value?

Insulation rating is based on insulation’s R-value; how resistant to heat loss a material is. The R-value for blown-in cellulose is approximately 3.21 per inch. So in to have an R-value of 38 in your attic you would need approximately 11.7 inches of loose cellulose. Prices for loose cellulose insulation vary depending on location, manufacturing and sizes of bales. However, a bale should run you between $9 and $15 USD. As an example, Lowe’s stock cellulose bale runs about $12. This bale will cover about 16.5 sq. ft. with an R-value of 38. That means you will need approximately 58 bales to do 1000 sq. ft. at a cost of $696 plus any rental costs.

cellulose insulationCons of cellulose

There are some concerns that cellulose is flammable, but in fact it is treated and studies have shown that it is fire retardant. Cellulose insulation does have the capacity to hold and retain water, which means if you do have a leak; the water could remain in your walls for some time causing additional problems. Finally, since cellulose is a loose insulation the installation process can be very messy. There is the potential for mess from the blower to the installation area. It is important to seal any cracks or gaps first to prevent insulation from filtering down through the holes. Any later remodeling work can become messy if you have to cut into the wall or ceiling. Finally, even though cellulose is made from newspaper, there will be small particles floating in the air and it is wise to wear protective gear including; eye and respiratory protection.


What is it?

Fiberglass insulation is by far the most common type of insulation and is known by the fluffy pink or yellow material seen in attics, crawlspaces/basements, and stores across the country. As the name suggests fiberglass insulation is made from glass. The glass, which is made up of at least some recycled glass, is melted and then cooled, dyed and spun to create strands of glass fibers or fiberglass. The fiberglass is sprayed with an adhesive and layered upon itself to create the thick cotton candy like battings that are commonly seen. Most battings have a paper/plastic backing that acts as a moisture barrier preventing moisture buildup in the walls.

How is it installed?

fiberglass insulationFiberglass insulation typically comes in long battings (although there is also loose fiberglass insulation available). The battings typically need to be cut to fit in whatever cavity they are being installed in and, are, in the case of walls and crawlspaces, stapled or held in with thin metal rods. When installing them in the attic the insulation is cut to proper length and laid out. Fiberglass insulation can be a little more labor-intensive then blown-in cellulose since you need to move around and cut the insulation. But, fiberglass batting needs no special equipment or tools to install and can be done fairly quickly. Fiberglass battings are not nearly as messy as cellulose insulation.

What is fiberglass's value?

Fiberglass batting insulation has an R-value of approximately 3.14. The cost of fiberglass will vary depending on R-value, length, vapor backing and manufacturing. But for an example, Lowe’s sells R-38 precut in 48” length for approximately $45 and will cover approximately 43 sq. ft.  To cover a 1000 sq. ft. area would cost you approximately just over $1000 USD.

Cons of fiberglass

Fiberglass is not nearly as messy as cellulose insulation and doesn’t require special tools to install but there are still cons. Fiberglass is more expensive per sq. ft. compared to cellulose. Also because it is made of small strands of glass it can be an irritant. If you have ever handled it before you know that your arms and hands feel scratched and raw afterwards. To avoid this you should wear long sleeves and gloves as well as eye and respiratory protection when working with it.