Is rock wool insulation dangerous

Stone wool - for inexpensive and efficient thermal insulation

Stone wool (€ 34.95 at Amazon *) is an insulating material made of natural stone fibers, which has excellent insulating properties as well as heat and sound insulation properties. Together with the now obsolete slag wool and glass wool, rock wool is a mineral wool. Due to their physical properties, but also their low price, glass or rock wool insulation is one of the most frequently used insulation methods in Germany.

What are thermal insulation materials?

Insulating materials are building materials that have a large volume due to numerous cavities and are low in weight. Their thermal insulation effect results from the air resting in them, which has a low thermal conductivity compared to solids. The specific thermal conductivity (? - Lambda) of insulation materials used today is well below 0.1 W / mK. Efficient insulation materials play an essential role in energy-conscious building and thus contribute to the reduction of greenhouse gases. The insulation requirements for new buildings and renovations are also legally prescribed by the Energy Saving Ordinance (EnEV).

The thermal conductivity of insulation materials in comparison

Insulation materialsThermal conductivity (W / mK)Minimum insulation thickness according to EnEV (cm)Costs per m2 (euros)
Rock wool0,035 – 0,0401410 – 20
Glass wool0,032 – 0,0401410 – 20
Styrofoam / EPS0,035 – 0,045145 – 20
Calcium silicate0,0652480
hemp0,04 – 0,0451610 – 27

Glass and rock wool - at the top of the list when it comes to thermal insulation materials

Around 35 million m3 of insulation material is used in Germany every year. Estimates assume that glass and rock wool have been represented with a share of over 60 percent since the 1990s. There are also a number of other insulation materials made from synthetic raw materials, but increasingly also from organic material.

Stone wool - an invention from the 1930s

Stone wool was developed by the Bergisch-Gladbach company Grünzweig & Hartmann in the 1930s and patented in 1939 under the brand name "Silan". The aim of its inventors was to develop an insulating material whose raw materials were permanently available and to strengthen the company's competitive position compared to the somewhat long-established manufacturers of glass wool - also a German invention from the 1930s.

How is stone wool produced?

Stone wool is made from natural rocks at temperatures of around 1,500 ° C using a nozzle drawing process, the resulting stone wool fibers are then spun into a fleece. The usual starting materials are various diabase rocks, basalt, feldspar or dolomite. Today, recycled molded bricks are also used to a certain extent in their production. Rockwool recyclates may also be used. The binder content is around 4%. In small quantities (proportion < 1="" %)="" werden="" ihr="" außerdem="" mineralöle="" und="" silikonemulsion="" zugesetzt,="" die="" ihre="" hydrophoben="" (wasserabweisenden)="" eigenschaften="" verstärken.="">

Possible applications in many product variants

Stone wool comes on the market in the form of felts, plaits, mats, panels, and it can also be used as loose bulk insulation. According to DIN standard 4102-1, it is assigned to building material classes A1 or A2, including rock wool with an aluminum cladding, while non-woven or paper-clad rock wool is classified as a B2 building material. The criteria for the classification are the respective fire and flammability behavior.

What are the advantages of rock wool as an insulating material?

Stone wool has excellent insulating properties. Their thermal conductivity is 0.035 to 0.040 W / mK and is therefore on a level comparable to that of glass wool, hemp or styrofoam (EPS, expanded polystyrene particle foam). In the current EnEV (as of 2014), an insulation thickness of at least 14 cm is specified for thermal insulation with rock wool, but for roof insulation it should be more than 20 cm. Other advantages of rock wool are:

  • High sound insulation capabilities: Stone wool is therefore often used for sound insulation in storey ceilings as well as for partitioning rooms.
  • Very good heat protection properties: The relatively high density of rock wool means that the thermal energy of the solar radiation is released into the interior of the building with a time delay. The thermal protection factor depends on the thickness of the integrated rock wool insulation layer.
  • No absorption of moisture: Stone wool is completely water-repellent and unable to store moisture. It is therefore an extremely “breathable” insulation material - moist air diffuses unhindered through the outer wall. With these properties, stone wool helps to protect the building fabric from moisture and mold growth and to a pleasant indoor climate inside the building. The moisture and drying behavior of rock wool is generally rated as good by experts. In this respect, rock wool is clearly superior to biogenic (organic) insulation materials.
  • Resistance to vermin and mold infestation.

What are the disadvantages of rock wool insulation?

  • Like glass wool, rock wool does not tolerate high levels of moisture and can therefore only be used in largely dry environments. If rock wool is soaked, its insulating effect is gradually lost. When exposed to very high levels of moisture, the material collapses so that its insulating effect can no longer develop.
  • The relatively high density of rock wool, compared to various other insulating materials, also results in a higher weight load on the building structure. For this reason, lighter insulation materials are often used, especially for insulation on pitched roofs.
  • The production of stone wool is comparatively energy-intensive; between 150 and 400 kWh of primary energy are required per m3 for its production. However, the manufacturing processes for most of the other synthetic insulation materials are also energy-intensive. The fact that rock wool does not occupy a top position here is made clear by the consumption values ​​of so-called gray energy - the total amount of energy used for the production, transport, distribution, storage and disposal of products. Here, rock wool is at best in the good middle field and is also clearly superior to glass wool as its direct competitor product. In addition, effective thermal insulation permanently improves the energy balance of buildings.

What areas of application for stone wool in thermal insulation are there?

As a thermal insulation material, rock wool is mainly used for roof and ceiling insulation. One of their main areas of application is the insulation between rafters on roofs. Steep, fragile roof structures are an exception here, for the insulation of which the lighter glass wool is used. The insulation takes place here mainly in the form of insulation mats. For facade insulation with rock wool, mainly fleece-laminated insulation panels are used. In addition, rock wool is also used as a loose insulation material for blown-in insulation in cavities, sloping ceilings and in-accessible floor ceilings.

Excellent fire protection properties

Thanks to its good fire protection properties, stone wool is a good alternative to Styrofoam for both roofs and facades, which begins to melt at temperatures of just over 100 ° C and releases extremely easily flammable substances from around 300 ° C. Stone wool is not flammable, the flash point of the stone wool fibers is over 1,000 ° C.

Cutting and dismantling effort

Steep wool in sheet, mat or fleece form must be cut before use, which works best with a special insulation knife, but if necessary with a serrated household knife or other alternative devices. With loose laying, the dismantling effort for rock wool is low, whereas the dismantling of a fixed rock wool insulation is complex.

Stone wool or glass wool - which is better?

Stone wool and glass wool have comparable properties. Stone wool, however, gradually shows better heat and sound insulation properties. Due to its lower bulk density and, consequently, its lower weight, glass wool is sometimes better suited for insulation work on fragile structures. The price of rock wool and glass wool is almost identical. Facade insulation with rock wool is comparatively more economical to implement, roof insulation with glass wool is cheaper - the decision between the two materials should, however, be made less on the basis of price considerations and more on constructional reasons.

Comparison of costs for roof and facade insulation

Insulation materialRoof insulation costs per m2 (EUR)Facade insulation costs per m2 (EUR)
Rock wool1010
Glass wool720

How can stone wool be disposed of?

Rockwool waste occurs when replacing old thermal insulation made from this material, when cutting to size and as remnants of insulation work. Naturally, this insulation material is not biodegradable - proper disposal is therefore essential. In addition, rock wool is recyclable, and new insulation materials are produced from the "contaminated sites". It is ideal if users dispose of stone wool that is no longer required by using a recycling service. For example, the manufacturer Rockwool has been offering this service on a nationwide basis since 2007; tradespeople can also order the recycling service when ordering materials. Otherwise this task will be taken over by professional waste disposal companies. In Switzerland, manufacturer-specific recycling services for stone wool are now standard.

Only unpolluted rock wool is suitable for recycling, soiled material ends up moistened and packed in special sacks on the building material dump.

Is stone wool harmful to health?

There have been numerous debates in the past on the question of whether rock wool is harmful to health. Among other things, the material was said to have carcinogenic properties - however, this assumption was not confirmed by medical research. In 1999, the RAL seal of approval for products made from mineral wool was introduced, which certifies that they are harmless to health; stone wool produced in Germany is now without exception marked with it. Comparable quality and health standards apply within the European Community. During renovation and demolition work, however, contact with older and health-critical rock wool fibers can still occur.

In general, stone wool produced in Germany and Europe is not harmful to health. If the installation is carried out properly and tightly, there is no risk of damage to health from rock wool fibers, even indoors.

Fine dust from rock wool - good work safety is important

However, when processing and especially when cutting rock wool, there may be contact with fine dust. If you work with it, you should protect yourself with gloves and a face mask. In particular, professional craftsmen and construction workers who regularly come into contact with rock wool and other mineral wool should not do without a reliable breathing mask.

Stone wool is suitable for economical thermal insulation of roofs and facades.
The material not only ensures excellent thermal insulation, but also optimizes the fire protection of a house. Stone wool produced in Germany and the EU is harmless to health - look out for the RAL seal of approval when buying.

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