Rockwool insulation goes by several names including, mineral wool insulation, stone wool, slag wool, and rock wool.

Despite the many names, they all describe a versatile type of insulating material that is formed of fibers made from both natural and man made materials.

These materials are usually various types of natural and synthetic minerals, such as basalt, and metal oxides.

If you have a project for home or industrial structural insulation, soundproofing insulation, filtration, or hydroponics, then rockwool insulationn and mineral wool insulation is a good material to consider using.

Uses of Rockwool Insulation and Mineral Wool Insulation

rockwool mineral wool attic insulation

Rockwool insulation being blown into an attic.

Thermal Insulation:  When the fibers are combined into bulk wool or compressed sheets of fibers, there are tiny air pockets formed that trap air and hold in heat.  Some common applications are rockwool blown in insulation into attics, crawlspaces, between studs and behind drywall.  The rockwool insulation r value is approximately R-2.5 to R-3.7.

Fire Barrier Component:  The fibers are not fireproof, but when used within wall cavities it can act as an effective passive firewall.  It should not be used as a stand alone firestop, but as a packing material to hold another fireproof packing material.  By itself, the rockwool will provide no impedance to smoke migration and would be displaced in a real fire situation.

Hydroponics:  When the mineral wool fibers are treated or conditioned to reduce their natural pH level, they can be made into a suitable medium for growing certain types of plants.  Rockwool cubes will hold a great deal of moisture, while still allowing air flow, to help roots take hold and pull in nutrients.

Soundproofing:  The air pockets that make it a good thermal insulator also make rockwool insulation a good sound insulator.  Sound waves enter the insulation sheets and get trapped and dampened by the tiny interwoven air pockets.

Filtration:  When rockwool insulation is tightly packed into sheets, it can create an effective filter media.  When the material being filtered is ran through the media, the tiny air pockets and voids will catch and hold out the particles being filtered.

How Mineral Wool and Rockwool Insulation is Made

A furnace is filled with molten rock, at temperatures reaching 1600 degrees Celsius, and then streams of air and steam are forced through the furnace to create the streams of molten minerals which cool into fibers.  A similar method takes the molten rock onto a high speed spinning machine that spins off the fibers.

Both techniques produce very fine mineral fibers.  When the fibers are blown together they weave together to form a mass of fibers.  The mass of fibers can then be further processed into blown insulation, sheets, pipe fittings, filet media, brake pads, and more.

To reduce dangerous dust exposure, the mineral wool and rockwool are sometimes combined with a small amount of oil and food starch that bind together, thereby knocking down the particles, and giving us the final usable products.