Fiberglass consists of extremely fine glass fibers. It is found in most homes' insulation and is commonly used in two different types.
This type of fiberglass insulation is manufactured in the form of blankets that come in rolls. These blankets can be installed in unfinished attics, walls, basement ceilings and crawlspaces, keeping the temperature in the conditioned space constant.
Fiberglass batts are manufactured with a paper or foil backing that acts as a vapor barrier and also allows for them to be stapled in place with the backing facing towards the conditioned space.
This type of insulation is installed using a machine to fluff the loose fiberglass while blowing it through a hose to the desired location. When installed correctly, it will provide additional air sealing which improves air quality due to the tighter seal.