Insulation Blog Series: Part 2 - Fiberglass vs. Cellulose
Posted by Damien Cabral on Mon, Oct 12, 2009
One of the most epic battles in home improvement is focused around insulation materials. Fiberglass and Cellulose are the most common materials used in home insulation. In this blog article, we will compare the materials head to head in an unbiased fashion (we sell both fiberglass and cellulose insulation in New England so you can trust us.)
Product Performance
When we compare R-Values (explained in the previous insulation blog article), both products are similar. It is important to note that "R-value per inch" does not matter because the R-value rates the resistance of heat flow. 12" of insulation rated at R30 will achieve the same effect as 18" of insulation rated at R30. Therefore, you can conclude that the products are equal when we compare thermal resistance.
Settling
Settling refers to the gradual sinking of the material. Usually fiberglass has minimal settling and will appear to hold the same thickness as the day it was installed. Cellulose settles at a higher rate, sometimes up to 20%.
Fire
Fiberglass is naturally noncombustible because it is made of spun glass, which is essentially sand. No additional fire retardant material is added to fiberglass insulation. Cellulose is newspaper based, which is naturally combustible. Cellulose insulation is treated with fire retardant chemicals. Occasionally this chemical may lose its effectiveness over time and could pose as a fire hazard later in it's useful life.
Wet Insulation
It is safe to say when insulation gets wet, it loses its R-value. Insulation blocks the transfer of heat by creating small air pockets. When these air pockets are filled with water, they are less effective. Fiberglass is not absorbent and under normal circumstances, will not wick or hold water. Cellulose, on the other hand, is made of recycled newspaper, a material that naturally absorbs moisture.
Weight
Fiberglass gives a higher insulating value per pound installed than cellulose. This places a lower level of stress on your ceiling's drywall.
Sound
Both fiberglass and cellulose have been shown to be excellent sound insulators when properly installed.
Corrosion
Fiberglass is not corrosive and contains no chemicals. Cellulose contains a fire retardant chemical, which occasionally has been show to corrode pipes and wires.
Green
The fiberglass insulation industry utilizes recycled glass containers (generally 30% of the product) and helps to decrease landfill size. Cellulose utilizes recycled newspaper and is generally made up of 80% recycled material.
In conclusion, Moonworks generally directs our customers toward the fiberglass insulation product because it performs at the same level as cellulose with less of the potential negative side effects. Be sure to check out the prior installment of this blog article: Insulation Blog Series: Part 1 - The Basics.
Sources: NAIMA