mineral wool loose fill
Unbound mineral fibers used as loose thermal insulation, including rock wool and blast-furnace slag wool.
Mineral wool loose fill is a thermal insulation material made from loose fibers of mineral origin, usually from basalt, diabase, or iron ore blast furnace slag. It is similar to fiberglass in appearance, with airflow resistance depending on its density and installation. Its effectiveness can be reduced temporarily when it becomes wet or moist. This insulation material refers to mineral wool which is not bound together in sheets or other forms, but can be stuffed in any amount to fit the required space in a wall or roof.
The fibers remain loose and can fill a cavity without forming a prefabricated sheet. Mineral-wool boards and batts have different material forms.
Rock-derived fibers and slag-derived fibers are included. Their performance depends on the installed material and its condition, including moisture exposure.