The difference between rock wool and glass wool
Glass wool insulation products and rock wool insulation products have now become the main insulation materials. Household needs, industrial needs, enterprise use, and various insulation material engineering. Having suitable insulation materials is very important. Both have their advantages and disadvantages. We will outline some important factors that need to be considered when deciding whether glass fiber or mineral wool is suitable for your project.
Glass wool (glass fiber)
Glass wool, also known as glass fiber, is made from a mixture of natural and recycled glass (recycled bottles, car windshields and window glass), melted at 1,450°C, then quickly spun into fibers. These fibers are then bonded together for use as insulation material. Glass fiber creates air pockets that act as a barrier against heat loss, because air is a poor conductor of heat. Glass wool can be found in batts and rolls, as well as in insulation boards.
Rock wool (asbestos, slag wool)
Made from volcanic rock (dolomite, diabase and basalt), not a recyclable material, but an abundant resource. Slag wool is made from recycled waste from blast furnaces. Asbestos provides higher quality and performance products than slag wool, although both are commonly referred to as rock wool. These raw materials are processed similarly to glass, they are melted at high temperatures (about 1,500°C), then spun into fibers. This fiber is then packaged into batts, rolls or slabs.
Compared with glass wool insulation materials, there is much debate about the advantages of rock wool. There is also a lot of misinformation about these two materials. The simple answer is that the good material depends on the application and specific performance requirements.
R-value
The R-value measures the resistance of an object to heat transfer from one side to the other. The higher the R-value, the greater the resistance and the better the insulation effect. When comparing the two, glass wool has a slightly lower R-value, about 2.2-2.7, while mineral wool has an R-value of 3.0-3.3, which means it is slightly less effective in preventing conductive heat loss.
Compressive strength
When the structure may bear high weight loads, compressive strength is required. Not only is the density of rock per cubic meter as high as 200 kg (compared to 110 kg for glass), but it can also provide more cost-effective performance when compressive strength is the main requirement. A typical application requiring compressive strength is flat roofs.
Sound insulation
In terms of sound insulation, mineral wool tends to be the first choice in noisy areas. This is because it is denser than glass wool, so much less sound passes through the insulation material.
Fire protection performance
Although both rock wool and glass wool are non-combustible, rock wool has much better fire protection performance, so much so that it can be used as a fireproof material. The simple fact is that high-density mineral wool products (120 kg per cubic meter) are needed to extinguish fire. At these densities, rock wool is a more cost-effective solution and provides excellent fire protection. However, like glass mineral wool, low-density rock wool insulation material will not burn, but it will not prevent flames from penetrating between the fibers either. In short, for building fire protection, high-density rock wool is the ideal solution.
High temperature applications
High temperature use temperature is a measure of the high continuous temperature at which insulation material can work without losing any insulation performance. A common misconception is that this is the higher temperature before the product burns. This is not the case, all mineral wool is non-combustible. However, compared with glass wool, rock wool can withstand higher temperatures without losing its insulation performance. Usually, glass mineral wool can work at temperatures up to 400°C (usually 230°C unmodified), while rock can work at temperatures up to 700°C. Therefore, in high-temperature processing plants, rock wool is the more common type of insulation.
Water resistance
It is a common misconception that glass or rock mineral wool fibers are damaged by water. However, water will occupy the space between the fibers, thereby preventing the material from performing its insulation requirements. The lighter the density, the easier it is for water to penetrate. Importantly, the water resistance of mineral wool (glass and rock) can be designed to meet its application conditions, and silicon is added as a waterproof agent to prevent water from seeping into the pores in situ in the application.
Moisture resistance
If you are looking for a moisture-resistant form of insulation, rock wool is undoubtedly a choice. Rock wool board is water-resistant, so it will not get damp, and will not provide good growth conditions for the growth of fungi, mold, mildew or other bacteria. On the other hand, glass wool will get damp, and will promote the growth of fungi, mildew and rot, and its insulation performance will be seriously reduced.
Easy to install
If you are considering installing insulation material yourself, rock wool is considered easier to handle. Although heavier than glass wool, rock wool is easier to cut, move and install in place. On the other hand, glass wool is softer, which makes it difficult to adapt to the required space. Especially glass wool will generate a lot of fine dust during the construction process, and people who work directly will be very itchy. Therefore, it also requires skilled workers.
The fiber characteristics of glass wool are conducive to high compression of the product without affecting the recovery to the required thickness after unpacking, thereby improving transportation and storage efficiency. The characteristics of rock wool do not allow the product to be highly compressed in packaging, resulting in relatively low transportation and storage efficiency.
Cost
If your budget is limited, then glass wool may be your insulation choice. Its cost is about 10% lower than rock wool, and it can still effectively insulate your house to reduce heat loss and energy costs.
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