fiberglass and mineral wool insulation

Fiberglass and mineral wool have the same uses and forms as insulation products.

Fiberglass

Either in its loose-fill or in rolled blankets and batts forms, fiberglass is by far the most common type of insulation material in home buildings. Fiberglass is made from molten glass, and is usually presented in yellow or pink.

Mineral wool (rock wool, slag wool..)

Mineral wool is manufactured similarly to fiberglass, with molten rock instead of glass, and also comes in batts or rolled blankets, or loose-fill. This material is more common in Europe, Australia, Canada and New Zealand than in the U.S. and it's a good alternative to fiberglass.

The uses of fiberglass and mineral wool

Fiberglass and mineral wool are very similar in their uses, forms and properties.

In their loose-fill form they are particularly suited to insulate irregularly shaped areas, hard-to-reach places, areas with obstructions, unfinished attic floors or wall cavities.

Fiberglass and mineral wool blankets and batts are commonly used in foundations and unfinished walls, ceilings and floors. They are commonly installed between studs, joists and beams, specially when they involve standard spacing and are free from messy obstructions.

Installation

Fiberglass and mineral wool blankets and batts installation is a do-it-yourself job, contrarily to loose-fill installation. Be carefull howerver: inadequate installations will lower the R-value of the insulation. If the batt aren't well fitted with the surrounding structures, the effectiveness will be much lower.

Loose-fill fiberglass and mineral wool installation demand special equipment to be blown into place, and some knowing about thickness and application rules… It's not a DIY job.

Performance and Prices

Rockwool R-value is higher slightly higher than that of common fiberglass: approximately R-3.7 per inch, which amounts to high-density fiberglass batts or cellulose R-values.

Mineral wool has a higher density, and can provide better acoustical and insulating results than fiberglass. Besides, mineral wool doesn’t lose its insulating value when wet, and has an outstanding resistance to fire.

However, since mineral wool is a less common material, its prices are often higher and much more variable than those of fiberglass.

Safety

Mineral wool and fiberglass are very safe insulation materials.

Some health experts claim that fiberglass fibers, when inhaled, are carcinogenic. But institutions as the American Lung Association state that fiberglass insulation “is safe, when it is properly installed”. The very fact that fiberglass is in use as a home insulation material since the 1930 without reported health problems, supports this last position.

Be careful, anyway. Direct contact with fiberglass materials (or exposure to airborne fiberglass dust) may indeed irritate the skin, eyes, nose and throat, cause itching, which ultimately can be cause of lung cancer: installation should be properly done, to avoid unwanted exposure; fiberglass insulation packages display cancer warning labels in many countries and governmental institutions (the U.S. Occupational Safety and Health Administration (OSHA), the International Agency for Research on Cancer (IARC) and the National Toxicology Program (NTP)..).