Is price the only significant difference between glass and stone wool? Which product provides better insulation properties? Which insulation is better for facades, and which for partition walls? Are stone and glass wool harmful to health?
In everyday jargon, the division between stone and glass wool is often referred to as mineral and glass wool, which is incorrect. Namely, both stone and glass wool are of mineral origin. Glass wool is made from about 80% broken glass, while the remainder consists of quartz sand and binding materials. Stone wool, as its name suggests, is made from stone of eruptive and sedimentary origin.
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Also, there is often debate about which insulation is better, stone or glass wool. In principle, there’s no answer to this question because these are two different insulation materials with different properties. Therefore, their areas of application are not entirely the same, and as such, they cannot be directly compared. Generally, the price of glass wool is somewhat more favorable, but one cannot usually replace the other.
Different mechanical and insulation properties
Due to the different production technologies and the different materials they are made of, stone and glass wool have different mechanical and insulation properties. Stone wool has better mechanical properties, primarily because of its denser structure. Because of its higher strength, stone wool is produced and sold in panels of various thicknesses. On the other hand, glass wool is less dense. Thanks to this, it can be compressed, which is more convenient for transport. It is packed and sold in rolls.
This difference in mechanical characteristics results in different applications. Glass wool, being softer, is more suitable for various fillings where significant mechanical properties are not required, such as fills for sloping roofs, partition walls. Glass wool adapts much better to different shapes, thus more efficiently filling various spaces.
Therefore, it is good at preventing the formation of thermal and sound bridges, i.e., areas without insulation. Stone wool has better mechanical properties, so it is used for insulating flat roofs, for insulation of sloping roofs from the outside. Also, the greater strength of stone wool makes it a better choice for external wall insulation, or for making contact facades.
Both insulation materials belong to fire class A1
In addition to these mechanical differences, stone wool has a wider range of applications concerning fire protection. The melting point of stone wool is around 1100 degrees Celsius (aprox. 2000 degrees Fahrenheit), while the melting point of glass wool is around 650 degrees Celsius (aprox. 1200 degrees Fahrenheit). However, it should be noted that both insulation materials belong to fire class A1 because their melting point is above 500 degrees Celsius (aprox. 930 degrees Fahrenheit).
When it comes to insulation properties, a direct comparison cannot be made. Namely, the higher the density of stone wool, the better its insulation properties, while for glass wool, the opposite is true. Since both types of insulation are offered in different densities, a definitive assessment of which insulation material is better cannot be given.
As for moisture resistance, the situation is unresolved. Additives are added to both stone and glass wool to protect them from moisture, but neither insulation material is suitable for places with high humidity. Regarding sound insulation, glass wool has a slight advantage, but these are nuances that probably don’t make much difference in practice.
Also, when making partition walls from plasterboard panels, glass wool is much more suitable because, as mentioned, it fills all openings more easily. Thanks to this, the partition wall is better “snug” inside, providing better thermal and sound insulation.
Are stone and glass wool harmful to health?
Stone and glass wool are also accompanied by the myth that they are harmful to health. This originates from past times, several decades ago, when these insulation materials were produced with completely different technological processes. Glass wool used to have much thicker fibers that were sharper.
Workers handling these insulation materials had to wear special protective equipment to protect their hands, eyes, and respiratory tracts; irritations and injuries were common. Therefore, the unfounded opinion remained to this day that stone or glass wool is not good for the health of residents.
The International Agency for Research on Cancer (IARC) confirmed in October 2002, for the second time, after 15 years of research (the first decision was made in 1988), that no insulation product made of mineral wool is carcinogenic or otherwise hazardous to human health, both for workers who install it and for the population living in buildings insulated with these materials.