Cellulose Loose-Fill Insulation
The term cellulose refers to the base fiber for all plant life. Wood, paper, and other plant-based products all are cellulosic materials. Cellulose loose-fill insulation is produced from recovered wood pulp materials. These include used newsprint and boxes that have been shredded and pulverized into small fibrous particles and subsequently treated with boron-based chemicals to make the material fire retardant. Dry loose-fill cellulose insulation is installed in attics and walls with pneumatic blowing machines, whereas existing walls may be insulated by blowing insulation in through access holes (Fig. 7.3).
Figure 7.3 Cellulose installation by pneumatic equipment. (Greenstone)
Originally manufactured as a sound deadener, cellulose soon caught on as an effective, dense insulation material. Early cellulose insulation remained a small portion of the market as fiberglass became increasingly popular after World War II. When the energy crisis arose in the 1970s, the demand for better insulation grew, and a resurgence of interest in cellulose insulation soon followed. The cellulose industry expanded rapidly, but the increased demand allowed a number of inferior manufacturers to enter the competition. Once the energy crisis subsided, the cellulose industry experienced a shakeout and again settled into a relatively small share of the insulation market. The 1980s saw relatively few changes in the products or the ranks of major cellulose insulation producers. Consequently, the number of active cellulose producers reduced in number from 200 companies in 1983 to 61 companies in 1991.3
According to the Cellulose Insulation Manufacturers Association (СІМА), an advocacy organization for the cellulose insulation industry, cellulose commands about 10 percent of the insulation market. Cellulose dominates the manufactured homes market (at least 60 percent) and enjoys a healthy share of the retrofit industry.
Another form of cellulose insulation, spray-applied in wet or damp form, is covered in Chap. 9. As a self-supporting material, it relies on water, adhesive, or a combination of both to build bond strength to a substrate and within itself. Spray-on products also may be used in wall cavities (fully open and dried before covering) or on other suitable exposed wall or overhead surfaces.