Typically manufactured in two different forms — pre-cut batts and rolls, and blown-in loose-fill — fiberglass building insulation is used primarily for thermal and acoustical purposes in wall cavities, attics, and other critical open spaces in building assemblies. One of its key advantages is value. Fiberglass insulation has a lower installed price than many other types of insulating materials and, for equivalent R-Value performance (i.e., thermal resistance), it is generally the most cost-effective option when compared to cellulose or sprayed foam insulation systems.
Fiberglass insulation helps make buildings more thermally efficient by better retaining the desired temperature of enclosed spaces, whether they are heated or cooled. Its thermal performance reduces utility costs for building owners, conserves nonrenewable fuel sources and provides greater occupant comfort (when used in conjunction with appropriately sized heating and cooling equipment).
When exposed to moisture, fiberglass insulation neither absorbs nor holds water. If fiberglass insulation does get wet during or after installation, installers should visually inspect it on all six sides for contamination. If the material appears free of visible defects, installers must dry it thoroughly to restore its full R-Value. Once the area surrounding the insulation has also been inspected, cleaned and fully dried, the fiberglass insulation can be reinstalled and will regain its original R-Value.
Made from sand and recycled glass, fiberglass insulation is naturally noncombustible and remains so for the product’s life. It requires no additional fire-retardant chemical treatments. Many building codes also recognize fiberglass insulation as an acceptable fire stop in wood- and steel-framed wall assemblies.
Fiberglass insulation is a naturally sound-absorbent material that significantly reduces sound transmission in wall, ceiling, floor, and HVAC assemblies. The first inch of fiberglass insulation in a building cavity can increase an assembly’s sound transmission class (STC) value by three or four points in some constructions. Each additional inch can further increase the STC rating by two points.
Between 1992 and 2000, the fiberglass insulation manufacturing industry recycled more than 8 billion pounds (3.6 billion kg) of pre- and post-consumer glass containers, eliminating the need for millions of cubic feet of landfill space. Fiberglass insulation has significant recycled content, with some batt, roll and loose-fill insulation products containing up to 80 percent recycled glass. The other main ingredient in fiberglass insulation, silica sand, is an abundant, naturally renewing resource, limiting environmental impact in the manufacturing process.