Fibreglass vs Cellulose Insulation?

A question you might ask yourself, "Should I use fibreglass insulation or cellulose insulation?"

At Arctic Attics, we would like to help you answer that question.

Fibreglass insulation is the industry standard. It is currently used by builders in 70% of new homes, and has a long history of usage dating back to at least 1933.

Cellulose insulation has been in relative widespread usage since the late 1970's. It is made from recycled newspaper and is blown in much the same way as blow-in fibreglass insulation.

Arctic Attics strictly uses Owens-Corning fibreglass insulation. We firmly believe the benefits of fibreglass far outweigh the few advantages of cellulose.

Benefits of Fibreglass Insulation
Fibreglass insulation has been widely used, tested and is a proven effective and safe thermal insulator. It has been used since the mid 1930's and has been installed in over 35 million homes across Canada. It is still used in the vast majority of new home constructions, and is designed to maintain its insulating properties over the lifetime of the product.

Cellulose, like fibreglass, is rated on its thermal insulating capabilities in "R-values". It has been argued that cellulose has a higher R-value than fibreglass for a given volume. This is true, however, unlike fibreglass, once cellulose has been blown into a wall, it will settle - meaning that if cellulose is blown in to meet a given R-value, after a few years the cellulose will have settled and it will not meet that same R-value any longer. Fibreglass, once installed, will not settle and will maintain its R-value for the lifetime of the home.

Cellulose is made primarily from recycled newspaper. While the concept of using discarded newsprint is certainly attractive from a recycling perspective, in reality, modern fibreglass is made from a majority of recycled glass. In fact, Owens Corning, the industry-leading multinational insulation manufacturer, uses no less than 70% recycled glass in their Canadian fibreglass products. For each joule of energy consumed in producing fibreglass insulation, 12 joules of energy per year are saved over the lifetime of the home.

Cellulose, being derived from paper, would typically be a fire hazard, but it is coated with flame retardant chemicals to achieve its flame-resistant characteristic. The proportions vary depending on the cellulose tested, but are generally 80% recycled newspaper and 20% fire retardant chemicals. In an average 1200 square foot attic, insulating to R40 with cellulose would introduce about 300 pounds of fire-retardant chemicals into the house. Fibreglass, being derived from sand, inherently is inflammable and requires no chemical additives.

Cellulose also does not achieve its rated R-value unless it is completely dry, and cellulose itself can collect moisture. If the cellulose insulation collects enough moisture it can cause rotting of framing members. There are studies that demonstrate cellulose insulation can corrode nails, bolts, copper wiring, electrical boxes, copper piping and steel studs in the presence of moisture.

Fibreglass insulation is not absorbent, any moisture lies on the surface of the fibres and can not penetrate them. When fibreglass is exposed to moisture vapour, moisture simply passes through the fibreglass and condenses on the next surface below the dew point temperature. These droplets then evaporate or drain away. As such, fibreglass is incapable of absorbing any moisture, preventing build up around wood and steel, and also will not corrode steel or copper materials. Additionally, fibreglass does not support biological or bacterial growth by nature.

Finally, fibreglass insulation is an easier material to work with than cellulose, being preferred by insulation installers to other insulation materials. Cellulose installation is generally messier to install and difficult to work with, meaning a fibreglass installation will make the job quicker to accomplish and with less complication than a cellulose installation.