What parameters should a good mineral wool have?

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Mineral wool is one of the most popular materials when it comes to insulating houses and apartments. Therefore, it is worth knowing what parameters we should pay attention to when buying it so that it fulfils not only its thermal insulation task but also improves interior acoustics and guarantees fire resistance in case of fire

Which mineral wool to choose – glass or rock?

Mineral wool is a product which is divided into many categories, and one of them is the one related to materials used for its production. In this connection glass mineral wool and rock mineral wool are distinguished

Glass mineral wool

This type of mineral wool is manufactured by melting, as the name suggests, quartz sand, cullet, limestone and gabbro. Glass wool is characterized by lower density, therefore it is less resistant to compression and high temperature

Stone mineral wool

On the other hand, rock wool, or rock wool as some call it, is made of stones such as basalt, gabbro, dolomite or limestone. Sometimes waste materials such as slag or mineral briquette are also used for its production. It is most often used for industrial buildings, insulating chimneys and any places where it will be exposed to high compression

5 most important parameters of mineral wool you need to pay attention to

Choosing an appropriate type of mineral wool for given surfaces is not everything though. It is also necessary to pay attention to its key parameters which allow for obtaining the best results. The five most important parameters include: thermal conductivity coefficient, thickness, flammability class and vapour permeability and resistance

Thermal conductivity

It is one of the most important parameters which should be paid attention to. It decides about effectiveness of made thermal insulation. However, it is worth remembering that, contrary to appearances, the lower the thermal conductivity coefficient, the better thermal insulation parameters of glass wool, and this in turn translates into lower heating bills in autumn and winter

Mineral wool with a thickness of 20 centimeters should have a thermal conductivity coefficient of 0.033-0.038 W/mK, while values over 0.040W/mK can be achieved by mineral wool with a thickness of about 23 centimeters

Thickness of mineral wool

Thickness of mineral wool is another important parameter, as the first of the described parameters depends on it. Currently, the market sells mineral wools with a thickness of 20 to 30 centimeters dedicated to installation on roofs and in areas exposed to high cooling, as well as those with a thickness of 10 centimeters

Flammability class

The flammability class determines the resistance of the material to the effects of flames. The best solution is a product with non-flammable properties, marked as A1 or A2 flammability class. This type of mineral wool prevents fire from spreading, does not emit toxic substances in the process of burning and melts only at the temperature of about 1000 degrees Celsius

As a result, not only does it not contribute to the spread of fire, but it also forms an effective fire barrier that allows efficient and safe evacuation in case of fire


This parameter prevents dampness of places thermally insulated with mineral wool. It is determined most often by the water vapour diffusion resistance coefficient. The lower it is, the water vapour can freely penetrate the insulation fibres, thus reducing the risk of fungal and mould growth


Under this professional term is hidden a parameter called the declared thermal resistance Rd. It is responsible for determining thermal insulating power of a given product. Its value strictly depends on the mineral wool thickness. In its case it is worth remembering that the bigger the thermal resistance is, the

Peter Bowers

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