Whether you are increasing the insulation levels in your current home or selecting insulation for a new home, choosing the right insulation material can be challenging. Fibrous loose-fill insulations such as cellulose, fiberglass, and rock wool are options you may wish to consider. This publication will introduce you to these materials—what they are, how they are applied, how they compare with each other, and other considerations regarding their use—so that you can decide whether loose fills are right for your home.
The most obvious difference between loose fills and other types of insulation is their form. They are either produced as—or broken down into—shreds, granules, or nodules. These small particles form fluffy materials that conform to the spaces in which they are installed. Loose fills are most commonly sold in bags and are blown into building cavities using special equipment. All three primary types of loose-fill insulation are considered “environmentally positive” because recycled waste materials are used in their production. Cellulose loose-fill insulation is made from wastepaper, such as used newsprint and boxes, that is shredded and pulverized into small, fibrous particles. Chemicals are added to provide resistance to fire and insects. Also, less energy is required to produce loose-fill cellulose than to produce other insulations.
Fiberglass loose-fill insulation is spun from molten glass into fibers. The glass is typically melted in high-temperature gas furnaces. Most major manufacturers use 20% to 30% recycled glass content. Rock wool (or slag wool) loose-fill insulation is similar to fiberglass except that it is spun from blast furnace slag (the scum that forms on the surface of molten metal) and other rock-like materials instead of molten glass. The production of rock wool uses byproducts that would otherwise be wasted.